new research on vaccines and autism

A positive association found between autism prevalence and childhood vaccination uptake across the U.S. population

Affiliation.

• 1 Department of Economics and Finance, Baruch College/City University of New York, New York, New York, USA. [email protected]
• PMID: 21623535
• DOI: 10.1080/15287394.2011.573736

The reason for the rapid rise of autism in the United States that began in the 1990s is a mystery. Although individuals probably have a genetic predisposition to develop autism, researchers suspect that one or more environmental triggers are also needed. One of those triggers might be the battery of vaccinations that young children receive. Using regression analysis and controlling for family income and ethnicity, the relationship between the proportion of children who received the recommended vaccines by age 2 years and the prevalence of autism (AUT) or speech or language impairment (SLI) in each U.S. state from 2001 and 2007 was determined. A positive and statistically significant relationship was found: The higher the proportion of children receiving recommended vaccinations, the higher was the prevalence of AUT or SLI. A 1% increase in vaccination was associated with an additional 680 children having AUT or SLI. Neither parental behavior nor access to care affected the results, since vaccination proportions were not significantly related (statistically) to any other disability or to the number of pediatricians in a U.S. state. The results suggest that although mercury has been removed from many vaccines, other culprits may link vaccines to autism. Further study into the relationship between vaccines and autism is warranted.

• Autistic Disorder / epidemiology*
• Child, Preschool
• Regression Analysis
• Speech Disorders / epidemiology
• United States / epidemiology
• Vaccination / adverse effects*
• Vaccination / statistics & numerical data

• Introduction
• Conclusions
• Article Information

Vaccine refusal was identified based on International Classification of Diseases , Ninth Revision , Clinical Modification codes. The error bars represent 95% CIs.

eTable. Rate Ratios Comparing Full Vaccination Status Between Children With Autism Spectrum Disorder (ASD) to Children Without ASD, and Younger Siblings of Children With ASD to Younger Siblings of Children Without ASD by Time Periods

• Factors Affecting Vaccination in Children and Their Siblings After Autism Spectrum Disorder Diagnosis JAMA Pediatrics Comment & Response October 1, 2018 Sarah Qin, MBA; Shari King, MA; Sarabeth Broder-Fingert, MD, MPH
• Factors Affecting Vaccination in Children and Their Siblings After Autism Spectrum Disorder Diagnosis JAMA Pediatrics Comment & Response October 1, 2018 Scott S. Field, MD

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Zerbo O , Modaressi S , Goddard K, et al. Vaccination Patterns in Children After Autism Spectrum Disorder Diagnosis and in Their Younger Siblings. JAMA Pediatr. 2018;172(5):469–475. doi:10.1001/jamapediatrics.2018.0082

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Vaccination Patterns in Children After Autism Spectrum Disorder Diagnosis and in Their Younger Siblings

• 1 Kaiser Permanente Vaccine Study Center, Oakland, California
• 2 Institute for Health Research, Kaiser Permanente Colorado, Denver
• 3 Center for Health Research, Kaiser Permanente Northwest, Portland, Oregon
• 4 Kaiser Permanente Washington, Seattle
• 5 Center for Clinical Epidemiology & Population Health, Marshfield Clinic Research Institute, Marshfield, Wisconsin
• 6 Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena
• 7 Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, Georgia
• Comment & Response Factors Affecting Vaccination in Children and Their Siblings After Autism Spectrum Disorder Diagnosis Sarah Qin, MBA; Shari King, MA; Sarabeth Broder-Fingert, MD, MPH JAMA Pediatrics
• Comment & Response Factors Affecting Vaccination in Children and Their Siblings After Autism Spectrum Disorder Diagnosis Scott S. Field, MD JAMA Pediatrics

Question   After receiving an autism spectrum disorder diagnosis, do children obtain all of their remaining scheduled vaccines, and are the younger siblings of these children vaccinated according to vaccine recommendations?

Findings   In a matched cohort study of 3729 children with autism spectrum disorder and 592 907 children without autism spectrum disorder, we found that children with autism spectrum disorder were less likely to be fully vaccinated for vaccines recommended between ages 4 and 6 years. The younger siblings were also less likely to be fully vaccinated for vaccines recommended at any age.

Meaning   Children with autism spectrum disorder and their younger siblings are at increased risk of vaccine-preventable diseases.

Importance   In recent years, rates of vaccination have been declining. Whether this phenomenon disproportionately affects children with autism spectrum disorder (ASD) or their younger siblings is unknown.

Objectives   To investigate if children after receiving an ASD diagnosis obtain their remaining scheduled vaccines according to the Advisory Committee on Immunization Practices (ACIP) recommendations and to compare the vaccination patterns of younger siblings of children with ASD with the vaccination patterns of younger siblings of children without ASD.

Design, Setting, and Participants   This investigation was a retrospective matched cohort study. The setting was 6 integrated health care delivery systems across the United States within the Vaccine Safety Datalink. Participants were children born between January 1, 1995, and September 30, 2010, and their younger siblings born between January 1, 1997, and September 30, 2014. The end of follow-up was September 30, 2015.

Exposures   Recommended childhood vaccines between ages 1 month and 12 years.

Main Outcome and Measure   The proportion of children who received all of their vaccine doses according to ACIP recommendations.

Results   The study included 3729 children with ASD (676 [18.1%] female), 592 907 children without ASD, and their respective younger siblings. Among children without ASD, 250 193 (42.2%) were female. For vaccines recommended between ages 4 and 6 years, children with ASD were significantly less likely to be fully vaccinated compared with children without ASD (adjusted rate ratio, 0.87; 95% CI, 0.85-0.88). Within each age category, vaccination rates were significantly lower among younger siblings of children with ASD compared with younger siblings of children without ASD. The adjusted rate ratios varied from 0.86 for siblings younger than 1 year to 0.96 for those 11 to 12 years old. Parents who had a child with ASD were more likely to refuse at least 1 recommended vaccine for that child’s younger sibling and to limit the number of vaccines administered during the younger sibling’s first year of life.

Conclusions and Relevance   Children with ASD and their younger siblings were undervaccinated compared with the general population. The results of this study suggest that children with ASD and their younger siblings are at increased risk of vaccine-preventable diseases.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in communication and social interaction and the exhibiting of stereotyped behaviors, typically occurring before age 3 years. The etiology of ASD is unknown for the vast majority of cases; however, study findings suggest that both genetic 1 - 3 and environmental 4 - 6 factors have a role.

Despite numerous scientific studies 7 - 15 reporting no association between childhood vaccination and ASD, there remain concerns about such a connection for some of the public. 16 In recent years, rates of undervaccination and vaccine refusal have been on the rise in the United States 17 - 21 and have been associated with vaccine-preventable disease outbreaks. 22 - 24 Rates of undervaccination among the subpopulation of children with ASD have not been fully investigated. A survey conducted among 98 parents of children with ASD and 65 parents of children without ASD in Canada found that a lower proportion of children with ASD received their measles, mumps, and rubella (MMR) or diphtheria and tetanus toxoids and acellular pertussis and inactivated poliovirus (DTaP-IPV) vaccines compared with children without ASD. 25 Because the first dose of MMR and the first 3 doses of DTaP-IPV are recommended before the age when ASD can be reliably diagnosed (which is at least 2 years), it was not clear from that study if the lower observed vaccination rates among the children with ASD were a consequence of the child’s ASD diagnosis. In a recent letter to the editor, Glickman and colleagues 26 reported no significant difference between rates of vaccination of 71 children with ASD and those of 135 children without ASD. However, they found that families with children with ASD were less likely to vaccinate subsequent children. Other studies 25 , 27 - 30 also found that parents of children with ASD were more likely to either delay or refuse vaccination for their younger children. In a survey of 197 parents, Bazzano and colleagues 27 found that half of the parents of children with ASD changed vaccination practices for their younger children because of beliefs that vaccines contributed to their child’s ASD. After surveying 486 parents of children with ASD, Rosenberg and colleagues 30 found that almost 20% of parents declined or delayed MMR immunization in the younger siblings of children with ASD. Previous studies were limited by small samples, lack of comparable control groups, or restriction to specific vaccines.

The objectives of this study were 2-fold. First, we investigated if children after receiving an ASD diagnosis obtain all of their remaining scheduled vaccines according to the Advisory Committee on Immunization Practices (ACIP) 31 recommendations. Second, we assessed whether younger siblings of children with ASD receive all recommended vaccines on time compared with younger siblings of children without ASD.

The study population included children born between January 1, 1995, and September 30, 2010, and their younger siblings born between January 1, 1997, and September 30, 2014, who were members of integrated health care delivery systems (sites) within the Vaccine Safety Datalink (VSD). 32 The VSD is a collaborative project between the Centers for Disease Control and Prevention and 8 sites across the United States and captures comprehensive medical and immunization data for more than 10 million people annually. This study included data from the following 6 VSD sites: Kaiser Permanente Northern California, Kaiser Permanente Colorado, Kaiser Permanente Northwest, Kaiser Permanente Washington, Marshfield Clinic, and Kaiser Permanente Southern California. The study was approved by the institutional review board at each participating VSD site and the Centers for Disease Control and Prevention. Written informed consent was waived by each institutional review board because the study had no direct contact with patients.

In this retrospective matched cohort study, we compared the proportion of vaccination between children with ASD and those without ASD. We also compared the proportion of vaccination of the younger siblings of children with ASD with those of the younger siblings of children without ASD.

We defined ASD based on the presence of International Classification of Diseases , Ninth Revision , Clinical Modification ( ICD-9-CM ) codes 299.0, 299.8, and 299.9 in electronic health records on at least 2 occasions from birth until either the sixth birthday or until the end of follow-up (September 30, 2015), whichever was earlier. If the first diagnosis appeared before age 2 years, we required that the second diagnosis be assigned at 2 years or older. A prior medical record review study 33 demonstrated that identifying ASD using at least 2 diagnosis codes predicts valid ASD cases. We matched children without ASD to children with ASD on month and year of birth, sex, and VSD site. Younger siblings of children without ASD were matched to younger siblings of children with ASD on month and year of birth, sex, and VSD site. It is possible that multiple siblings of an individual with or without ASD were included because we did not limit the number of children per family.

To assess the vaccination patterns of children after receiving an ASD diagnosis, we only included children who were at least 7 years old as of September 30, 2015, and in whom ASD was diagnosed at 5 years or younger. We limited this assessment to vaccines routinely recommended between ages 4 and 6 years and ages 11 and 12 years. For the comparison of vaccination patterns of younger siblings of children with ASD and younger siblings of children without ASD, we included children (siblings) who were at least 1 year old as of September 30, 2015, and assessed vaccines routinely recommended by the ACIP at ages 1 to 11 months (vaccine doses given at birth were not assessed), 1 to 2 years, 4 to 6 years, and 11 to 12 years. Children who received all of their vaccine doses within the ACIP-recommended age limits were considered fully vaccinated. For example, we considered a child who received at least 1 dose of DTaP, at least 1 dose of MMR, at least 1 dose of IPV, and at least 1 dose of varicella vaccine between ages 4 and 7 years as fully vaccinated for vaccines recommended at ages 4 to 6 years ( Table 1 ) regardless of vaccination history before age 4 years. We required that children be health plan members during the periods the vaccines were recommended (eg, to assess vaccination status at ages 1-2 years, we required that the children be health plan members between ages 1 and 2 years). For the younger siblings, we assessed vaccination status regardless of ASD diagnosis. Vaccine refusal was identified using ICD-9-CM codes V64.05 and V64.06.

In our primary analysis, we investigated and compared the proportion of fully vaccinated children within each age category for children with ASD, younger siblings of children with ASD, and their respective matched controls. In secondary analyses, we also assessed the proportion of vaccinated children for each individual vaccine or vaccine series for children with ASD, younger siblings of children with ASD, and their respective matched controls. For the younger siblings of children with and without ASD, we compared the proportions of children who received fewer than the recommended vaccinations at each well-child visit (no more than 2 shots per visit or shot limiting in the child’s first year of life), as well as the proportion of parents (based on ICD-9-CM codes) who refused to vaccinate their children. We calculated crude and adjusted rate ratios (RRs) using log binomial regression analysis. Because full vaccination is more common than undervaccination, the odds ratio for fully vaccinated would not be a good estimation of the RR. Therefore, we estimated the RRs by using proc GENMOD in SAS (version 9.3; SAS Institute Inc), with the log function as the link with binomial distribution. In multivariable analyses, we included maternal age categories at the child’s time of birth (≤20, 21-29, 30-39, or ≥40 years), maternal self-reported race/ethnicity (Asian, black, white, Hawaiian, Hispanic, Native American, or other), child’s sex, and month and year of birth. We used SAS version 9.3 to conduct all analyses. All P values were 2 sided, and P  < .05 was considered statistically significant.

The study included 3729 children with ASD (676 [18.1%] female), 592 907 children without ASD, and their respective younger siblings. Among the children without ASD, 250 193 (42.2%) were female.

For vaccines recommended between ages 4 and 6 years, our analysis included 2855 children with ASD diagnosed by age 5 years matched to 483 961 children without ASD. The proportion of children who received all recommended vaccine doses ( Table 1 ) between ages 4 and 6 years was lower in children with ASD compared with children without ASD (81.6% [2331 of 2855] vs 94.1% [455 435 of 483 961], respectively) ( Table 2 ). The proportion receiving each individual vaccine was also lower among children with ASD compared with children without ASD. For MMR vaccine, 84.0% (2397 of 2855) of those aged 4 to 6 years with ASD were vaccinated compared with 95.9% (464 245 of 483 961) of those without ASD. After adjusting for maternal age at the time of the child’s birth and race/ethnicity (which were both associated with ASD in our bivariate analyses) and the matching variables (month and year of birth, sex, and site), children with ASD were significantly less likely to be fully vaccinated (adjusted RR, 0.87; 95% CI, 0.85-0.88) compared with children without ASD. Adjusted RRs were also significant for each individual vaccine.

For vaccines recommended at ages 11 to 12 years, the analysis included 874 children with ASD matched to 218 181 children without ASD. In this age group, the proportions receiving all vaccines ( Table 1 ) and each individual vaccine were similar between children with ASD and children without ASD, and adjusted RRs were not significant ( Table 2 ).

Within each age group, the proportion of children who were fully vaccinated with the recommended vaccines was lower among younger siblings of children with ASD compared with younger siblings of children without ASD. The difference in proportion of fully vaccinated children was greatest in the group aged 1 to 11 months ( Table 3 ). The proportion of children who received each individual vaccine was lower for younger siblings of children with ASD compared with younger siblings of those without ASD within each age group. After adjusting for covariates, younger siblings of children with ASD were significantly less likely to be fully vaccinated than were younger siblings of children without ASD within each age group, except for vaccines recommended between ages 11 and 12 years. Rate ratios of undervaccination comparing younger siblings of children with ASD and those without ASD were lowest in the groups aged 1 to 11 months and 1 to 2 years.

A higher proportion of parents of children with ASD refused to vaccinate their younger children compared with parents of children without ASD ( Figure ). These parents were also more likely to limit the number of vaccines administered during well-child visits in the group aged 1 to 11 months (73 of 881 [8.3%] for younger siblings of children with ASD vs 2789 of 189 144 [1.5%] among younger siblings of children without ASD, P  < .001). For both ASD cases and their siblings, we found no significant differences in the RR of undervaccination over time (eTable in the Supplement ).

In this large multisite study, we found that vaccine uptake was high overall. However, after receiving an ASD diagnosis, children with ASD were subsequently less likely to be vaccinated compared with children without ASD matched on age, sex, and site. We also found that vaccination rates were lower among younger siblings of children with ASD compared with younger siblings of children without ASD. Parents of children with ASD were more likely to refuse vaccinating the children’s younger siblings compared with parents of children without ASD. This phenomenon was not observed for vaccines recommended at ages 11 to 12 years for children with ASD and their younger siblings.

Our results are similar to those of a Canadian study, 25 which reported that children with ASD and their younger siblings were undervaccinated for MMR and pertussis-containing vaccines compared with children without ASD. However, there are major differences between our study and the Canadian study, including our larger sample size and more targeted study design. In our comparison of vaccination status between children with ASD and those without ASD, we only assessed vaccines recommended after the child’s ASD diagnosis, which enables the inference that the lower vaccination rate in children with ASD was at least in part owing to the ASD diagnosis.

In the present study, within each recommended age category of vaccination before age 10 years, younger siblings of children with ASD were significantly more likely to be undervaccinated compared with younger siblings of children without ASD, suggesting that the ASD diagnosis of the older sibling may have contributed to the undervaccination of the younger children. Knowing that younger siblings of children with ASD are at higher risk for ASD 34 - 37 may have led some parents of children with ASD to either delay or refuse vaccinations for the younger siblings. It is also possible that health care professionals may have been more likely to assign the code for vaccine refusal for the siblings of children with ASD when they know that the family has a child with ASD. Parents of children with ASD may also delay or alter the vaccination schedule of their younger children because of concerns that vaccines may have had a role in causing the ASD of the older siblings 27 , 30 ; this is despite considerable scientific evidence that vaccines do not cause autism. As previously reported, most parents vaccinate their children according to the ACIP-recommended schedule. 18 However, an increasing number of parents, especially parents of children with ASD, also appear to limit the number of vaccines their children receive during their child’s first year of life; the safety of such alternative vaccination schedules is unknown, but this practice increases the chances for contracting a vaccine-preventable disease.

The highest rates of undervaccination in this study were among siblings of children with ASD who were in the groups aged 1 to 11 months and 1 to 2 years. This suggests that some parents consider the potential risks of ASD associated with vaccination to be greatest at these younger ages at which more vaccines are recommended. However, as these children grow older, these parents may be more willing to vaccinate.

Our study has some limitations. Autism spectrum disorder status was determined using specific diagnostic codes from automated data, and medical record reviews were not conducted. However, our case definition, which required at least 2 codes for ASD on different days, has been shown to identify true cases of ASD with high accuracy. 33 Although the overall sample size of the study was large, the analysis comparing vaccination status of the younger siblings for the group aged 11 to 12 years was small, which limited the validity and power to observe differences in vaccine patterns in this group. We required that children in the study be a health plan member during the periods we assessed their vaccination status; while it is possible that some children may have received some of their vaccines outside of the VSD sites, this is considered unlikely because vaccines are offered free of charge at all of the participating sites. For missing vaccine doses to affect our results, the data missing would have to be differential for families with and without children with ASD. Our rates of undervaccination among children with ASD may reflect an underestimation of the true rates because we did not assess vaccination status before the ASD diagnosis. We did not conduct medical record reviews to validate the codes for vaccine refusal. Rates of vaccine refusal in this study likely underestimate the true rates of vaccine refusal because vaccine refusal is not always coded in the medical record consistently by physicians. Our rates could be biased toward or away from the null value because we cannot determine if ASD status is always associated with better or worse documentation of vaccine refusal. For some vaccines, different numbers of doses are recommended depending on which vaccine is used; we did not examine specific vaccine formulations. We were not able to assess the birth dose of hepatitis B vaccine because not all children included in our study were born at the health care organizations included in the study. Finally, we cannot attribute all of the undervaccination findings for the younger siblings of children with ASD to the ASD diagnosis of the older sibling because it is possible that some parents may have modified their younger children’s vaccine schedule without knowing the ASD status of the older children or for other reasons, including health care professional recommendations or some unknown factors.

This study’s strengths include our large racially/ethnically and socioeconomically diverse population 38 from 6 different geographic areas, suggesting that the findings may be broadly generalizable to other populations. We also used vaccination data validated from the medical record instead of a parental report, which could be subject to recall bias or incomplete information. Furthermore, we had extensive vaccination data over many years and were thus able to assess the vaccination rate for recommended childhood vaccines between ages 1 month and 12 years for the younger siblings of children with ASD. In addition, we were able to match a large comparison group with the children with ASD and identify the younger siblings of both children with and without ASD. By matching on month and year of birth, the study minimized the possibility of a difference in the interpregnancy interval between cases and controls or between siblings of cases and siblings of controls.

This large multisite study found that children with ASD and their younger siblings were undervaccinated compared with the general population, suggesting that they are at increased risk of vaccine-preventable diseases. Although we do not know all factors contributing to undervaccination among children with ASD, the results of our study suggest that parental vaccine refusal could have a role. Previous studies reported that a large proportion of parents of children with ASD consider that vaccines contributed to their child’s ASD, and consequently they either changed or discontinued vaccination, suggesting that current strategies to address vaccine hesitancy have not been effective for parents of children with ASD. New strategies, including establishing or promoting a better dialogue among parents, health care professionals, and public health authorities, may be needed to increase vaccine uptake in populations with low uptake.

Accepted for Publication: January 10, 2018.

Corresponding Author: Ousseny Zerbo, PhD, Kaiser Permanente Vaccine Study Center, One Kaiser Plaza, 16th Floor, Oakland, CA 94612 ( [email protected] ).

Published Online: March 26, 2018. doi:10.1001/jamapediatrics.2018.0082

Author Contributions: Drs Zerbo and Modaressi had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Zerbo, Goddard, Lewis, Daley, Irving, Jackson, DeStefano, Klein.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Zerbo.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Zerbo, Modaressi, Lewis, Fireman, Qian, Getahun.

Obtained funding: Goddard, McNeil, Klein.

Administrative, technical, or material support: Goddard, Daley, Irving, Jackson, Donahue, DeStefano, McNeil.

Study supervision: Zerbo, Daley, Klein.

Conflict of Interest Disclosures: Ms Irving reported receiving research grant support from MedImmune for unrelated studies. Dr Qian reported receiving research support from GSK and Amgen for studies unrelated to this publication. Dr Getahun reported receiving research grant support from the National Institutes of Health/ Eunice Kennedy Shriver National Institute of Child Health and Human Development and Bayer for unrelated studies. Dr Klein reported received research grant support from Sanofi Pasteur, Novartis, GSK, Merck, MedImmune, Pfizer, and Protein Sciences for unrelated studies. No other disclosures were reported.

Funding/Support: This study was funded in part by a grant from the Centers for Disease Control and Prevention.

Role of the Funder/Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in this study are those of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.

Additional Contributions: We express our gratitude to Roger Baxter, MD (Kaiser Permanente Vaccine Study Center, Oakland, California), who participated in the conceptualization of the study but passed away before the study was completed.

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Vaccines and autism: Separating facts from fiction

No scientific evidence points to childhood vaccinations causing autism, yet fears persist.

Despite comprehensive research saying otherwise, the rumor mill and unfounded reports perpetuate fear that child vaccinations are at the root of autism.

Numerous research studies have proven that autism spectrum disorder is not related to vaccination. This research has been conducted by the nation’s leading health experts, including the Centers for Disease Control and Prevention, National Institutes of Health, Autism Science Foundation, American Academy of Pediatrics and others. They all concur that there is no evidence vaccinations cause autism. So why do the rumors persist?

If you are the parent of a child with autism spectrum disorder, it’s understandable — and commendable — that you are searching for answers. It’s also understandable you want to know what causes this disorder.

Fact: There is no single cause of autism.

One of the reasons that the cause of this disease has been so hard to diagnose is because symptoms and behaviors vary so greatly among patients.

Medical experts know ASD is a neurodevelopmental disorder that affects early brain development. Communication problems, poor social interaction and repetitive specific patterns of behavior are common symptoms.

But because symptoms vary so greatly, autism is considered a “spectrum” disorder, meaning ASD is a group of disorders with similar features. People with ASD can be extremely intelligent, even gifted. Or they can have very low intelligence. Regardless, they interact, behave and learn differently from what we think of as typical.

Fact: Science has found no vaccine-autism link.

No scientific evidence has found a causal link between ASD and childhood vaccinations. More than 10 years ago, researchers agreed ASD and a possible relation to vaccines needed to be studied. The number of vaccines children were receiving was increasing. At the same time, the number of children with autism was on the rise.

“Fortunately, this was a question that could be studied — and answered — by science,” Autism Science Foundation leaders assert. “We looked at children who received vaccines and those who didn’t, or who received them on a different, slower schedule. There was no difference in their neurological outcomes. The results of studies are very clear; the data show no relationship between vaccines and autism.”

Fact: Multiple studies on vaccines and autism agree.

The Autism Science Foundation doesn’t ask you to take its word for it. ASF offers the studies as a recommended reading list for parents. Nor is it the only professional organization engaging in research on this topic.

The AAP released a statement including this information: “The American Academy of Pediatrics reiterates that vaccines protect children’s health and save lives. They prevent life-threatening diseases, including forms of cancer. Vaccines have been part of the fabric of our society for decades and are the most significant medical innovation of our time.

“Vaccines are safe. Vaccines are effective. Vaccines save lives. Claims that vaccines are linked to autism, or are unsafe when administered according to the recommended schedule, have been disproven by a robust body of medical literature.”

“There has been enormous debate regarding the possibility of a link between childhood vaccinations and the subsequent development of autism,” according to NIH. “This has in recent times become a major public health issue with vaccine-preventable diseases increasing in the community due to the fear of a ‘link’ between vaccinations and autism.

“We performed a meta-analysis to summarize available evidence from case-control and cohort studies on this topic. Reviewers extracted data on study characteristics, methods and outcomes. Disagreement was resolved by consensus with another author. Five cohort studies involving 1,256,407 children, and five case-control studies involving 9,920 children were included in this analysis. The cohort data revealed no relationship between vaccination and autism.”

NIH invites you to check out studies detailing its evidence.

“Cases of autism have risen over the last 20 years, from about 1 in 200 children in the 1990s to 1 in 59 today,” the CDC says. “This increase has led doctors and researchers to try to find out what is causing autism. But, much undue blame has fallen on vaccinations, especially from parents. Multiple CDC studies have debunked the link between vaccines and autism.”

A 2013 CDC study looked at the number of antigens (substances in vaccines causing the body’s immune system to produce disease-fighting antibodies) from vaccines during the first two years of life (the time period when it is thought autism is developing). The results showed that the total amount of antigen from vaccines received was the same between children with ASD and those that did not have ASD. The CDC concluded, “Vaccine ingredients do not cause autism.”

Fact: The original study claiming a vaccine-autism link has been debunked many times.

The autism-vaccination scare was fueled by a 1998 study a British scientist published, claiming there was a definite link. But this study was proven to be “erroneous, unscientific, and fraudulent.” The doctor who wrote it even lost his license. Yet, this study continues to be used as evidence today, continuing the spread of erroneous information.

Some say, “It’s not every childhood vaccination causing the problem. I’ve seen articles or media stories that link autism to thimerosal, a vaccination ingredient, and certain types of vaccinations – namely the MMR (measles, mumps and rubella). Or maybe children are just being given too many vaccines at the same time. I’ve heard that too.”

So is thimerosal the culprit? No. Due to autism-vaccination concerns at the time, thimerosal (a preservative included in childhood vaccinations) was removed from almost all vaccinations in 2001. Since its removal, autism cases have continued to rise.

Mercury also gets the blame. Some people speculate that mercury consumption from vaccines may be at the root of ASD. Reputable CDC studies using several different methods found mercury was not a cause of autism. Nor did the number of children diagnosed with autism decrease when mercury was removed from vaccines.

“Today, except for some flu vaccines in multi-dose vials, no recommended childhood vaccines contain thimerosal as a preservative,” the CDC states. “In all other recommended childhood vaccines, no thimerosal is present, or the amount of thimerosal is close to zero. No reputable scientific studies have ever found an association between thimerosal in vaccines and autism.”

In addition, the mercury found in multi-dose vials is different and less dangerous than the type of mercury found in fish, animals and the environment. Methylmercury, the type of mercury found in certain kinds of fish, can be dangerous and toxic at high levels. Ethylmercury, or the mercury in thimerosal, is less likely to cause harm, as it’s eliminated from the human body more quickly than methylmercury.

Since 2003, nine CDC-funded or conducted studies have been done looking for links between vaccination ingredients and ASD. None of the studies found any connection. If you read the NIH case studies, you will see that NIH case-control data also found no evidence for increased risk of developing autism or ASD following MMR vaccinations.

Fact: Autism spectrum disorder is likely genetic.

One of the things continuing to stir the pot is the cause of ASD is not known. Current research findings suggest there is a strong hereditary component. Scientists think ASD results from a complex interaction between several genes that play roles in brain signaling and development.

Environmental, biologic and genetic factors are believed to contribute to ASD. Almost all scientists agree genetics is a strong factor. Research has shown children who have a sibling with ASD are at higher risk. ASD also occurs more often in people who have certain genetic or chromosomal conditions. Children born to older parents are at greater risk for ASD.

Critical evidence exists suggesting the period for developing ASD occurs before, during and immediately after birth. Diagnosis of ASD usually takes time. There is no medical test defining it. Doctors look at the child’s behavior and development to make a diagnosis.

Sometimes, it can be detected at 18 months or younger. You can expect a fairly reliable diagnosis by the time your child is age 2. Medical specialists now consider a diagnosis of ASD to include several conditions that used to be diagnosed as separate. These include autistic disorder, pervasive developmental disorder not otherwise specified (PDD-NOS) and Asperger syndrome.

Fact: Some parents still aren’t sure.

Some parental beliefs refuse to disappear. A Journal of Preventative Medicine study published in May 2017 reported that nearly 8 out of 10 physicians report at least one vaccine refusal from a parent. Eight percent of physicians report refusals for more than 10 percent of children in their practice. According to a Harris Interactive/HealthDay poll published in January 2011, 18 percent of Americans say vaccines cause autism and 30 percent are not sure.

Families with one child with ASD are less likely to vaccinate younger siblings. Why? Because they are afraid the child with ASD got it from having the MMR vaccination. Even in studies where children were put on an alternate MMR schedule, autism diagnoses did not change.

And if you’re looking for a cure, you are probably running into a lot of fiction, too. The following treatments being sold have no established evidence of effectiveness: camel milk, gluten- and casein-free diets, certain vitamin supplements, secretin injections, anti-fungal agents, chelation, giant electromagnets, hyperbaric oxygen therapy, holding therapy, nicotine patch or actual snake oil.

Fact: Vaccination prevents many diseases.

More and more children are getting sick from vaccine-preventable diseases. Get your children vaccinated and encourage your friends to do so, too. Share with them what you have learned about the scientific data related to the non-effects of vaccines on autism.

Stay informed. CDC and numerous other health leaders are searching for ASD causes and factors. Resources are continually being developed to help identify and treat children with ASD as early as possible.

Currently, CDC is working on one of the largest United States studies ever done. Called Study to Explore Early Development (SEED), it is designed to find out if or how pregnancy or genetic, environmental and behavioral factors may put children at risk for ASD and other developmental disabilities.

Finally, trust your pediatrician. The AAP says, “Delaying vaccines only leaves a child at risk of disease. Vaccines keep communities healthy and protect some of the most vulnerable in our society, including the elderly, and children who are too young to be vaccinated or have compromised immune systems. Pediatricians partner with parents to provide the best care for their children, and what is best for children is to be fully vaccinated.”

If you have concerns about your child’s development, use the resources available to you. If your child isn’t receiving state assistance, call for a free evaluation. Research also shows when a child with ASD receives intervention services at an early age, development improves.

Contact your state’s public early childhood system for more information. You do not need a doctor’s referral — or even a medical diagnosis of autism for your child — to access these services. If you do not know where to call in your state, you can get the contact information by calling the Early Childhood Technical Assistance Center (ECTA) at (919) 962-2001.

• Autism and ADHD: How to know if your child should be tested
• Keeping your child with autism safe
• Immunization myths and when kids need each shot

Posted In Behavioral Health , Children's , Health Information , Immunizations , Inclusion at Sanford , Pregnancy , Women's

Our content is for informational purposes only and should not be relied upon as medical advice. The content is not designed to replace a physician's medical assessment and medical judgment. As always, please consult first with your physician about health matters. Click here for Terms and Conditions.

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Viral Posts Misuse Rat Study to Make Unfounded Claims About COVID-19 Vaccines and Autism

By Kate Yandell

Posted on January 26, 2024

SciCheck Digest

COVID-19 vaccination during pregnancy benefits both mother and baby. Side effects are generally mild, and studies don’t show negative effects on the baby. A criticized study that gave COVID-19 vaccines to pregnant rats doesn’t show that vaccines cause autism or that people shouldn’t get COVID-19 vaccines, contrary to claims.

COVID-19 vaccination  protects  pregnant people from severe COVID-19 and reduces COVID-19 risks for babies. As is the case in people who aren’t pregnant, side effects in  pregnant people  are usually mild and resolve within days. Studies  do not show  a link between COVID-19 vaccination and negative pregnancy outcomes or health problems for babies.

Long-standing claims that childhood vaccines cause autism have been  roundly   debunked . Long-term studies provide reassurance that vaccination during pregnancy against   flu  and  other  diseases does not increase a child’s risk of autism , a developmental disorder. And a recent  study  did not find a connection between maternal COVID-19 vaccination and increased risk of developmental delay at 18 months of age.

However, social media posts have misused findings from a recent  study  of COVID-19-vaccinated pregnant rats and their pups to back up unfounded claims that people should not take COVID-19 vaccines, or to promote unsubstantiated claims about vaccines and autism.

“I’m forever grateful I risked my reputation in my personal life to warn people far and wide to NOT get this experimental $h0t!” said one post sharing an article from the Epoch Times on the new study.

Commentator Candace Owens, who has a history of spreading misinformation, shared a post about the study on X, the platform formerly known as Twitter, saying it supported long-standing, debunked claims about vaccines and autism. “That’s because vaccines and autism have always been linked, which affected mothers have been trying to tell the general public for decades,” she said. Posts about the study have continued to spread .

Researchers who study brain development expressed concerns to us about how the rat study was designed and interpreted.

The authors of the study, published Jan. 10 in Neurochemical Research, did behavioral and other tests on rats born to 15 female rats impregnated by five males. The pregnant rats either received an adult human-sized dose of the Pfizer/BioNTech vaccine against COVID-19 or a saline injection. 

The researchers wrote that they observed “autism-like behaviors,” such as decreased interactions with an unfamiliar rat, and decreased neurons in regions of the brain in male rats born to vaccinated mothers. They also said they found alterations in the level of a particular protein in the brains of rats of both sexes born to vaccinated mothers.

Even if the results are taken at face value, it’s not possible to conclude from a study in rats that vaccines cause autism, because rat and human biology and behavior are different. Researchers do study rats to better understand autism, but these studies are meant to generate hypotheses, not change medical care.

Experts also told us there were various factors that made the study hard to interpret, such as the high vaccine dose given to the pregnant rats, despite their small size, the lack of replication of the experiment and issues with the statistical analyses.

“Caution should be exercised in generalizing these results to humans,” the authors themselves wrote in the paper. Corresponding author Mumin Alper Erdogan, a professor in the department of physiology at Izmir Katip Celebi University in Turkey, did not respond to a request for comment from us. However, he did answer questions from Health Feedback, responding to some criticisms and clarifying that there was “no intention, desire, or effort on our part to oppose vaccinations or make similar accusations.”

“Vaccines do not cause autism,” a spokesperson from the Centers for Disease Control and Prevention told us in an email. “To date, no vaccine safety monitoring data in the United States indicates a causal association between autism and COVID-19 vaccination.”

Rat Study Provides Limited Information

Multiple scientists expressed concerns to us about the high COVID-19 vaccine dose given to the pregnant rats.

Staci Bilbo , a neuroimmunologist at Duke University who studies how the immune system influences brain development, told us that vaccine doses are “extremely carefully” adjusted during vaccine development. Researchers determine the smallest dose that will generate the needed immune response.

Giving the rats — which on average weighed less than 8 ounces — a full adult human COVID-19 vaccine dose was equivalent to giving an average-weight American woman around 350 times the recommended dose of the Pfizer/BioNTech vaccine, according to Bilbo’s calculation. 

“If you give a high enough dose of anything it’s going to probably have impacts,” she said.

In response to questions about the dose, Erdogan told Health Feedback that “there’s no established standard for mRNA vaccine dosages in rats due to the lack of specific dose studies” and that relatively high doses have been used for studies of other animals of varying sizes.

Jeffrey S. Morris , director of the division of biostatistics at the University of Pennsylvania’s Perelman School of Medicine, also told FactCheck.org that the high dose given to the rats was a limitation of the study. “This does not make the results irrelevant, since super high dose can potentially detect some potential issue that might manifest in some humans, but if I were reviewing this article I would make the authors emphasize the multiple of how much larger the effective dose in the animal study is to the current human dose, and include the qualifier that this is one reason why it is not clear whether these results are relevant to what is experienced by humans given the current doses.”

Christopher Coe , a psychoneuroimmunologist and professor emeritus at the University of Wisconsin-Madison, told us via email that were it his study, he would also have wanted to give the rats a low dose of the vaccine to see if results varied by dose. Coe has done studies on the effects of infection and maternal inflammation on the fetus during pregnancy.

Coe said it was important to take reports of drug or vaccine adverse events seriously, but he also listed numerous other concerns about the paper.

For example, he said the researchers did not provide information about the rats and their pregnancies that could have shed light on how the injections affected them — and whether or not this was likely to be relevant to humans. This missing information included, for instance, whether the rats had an inflammatory reaction to the injections — the hypothesized pathway for how vaccination during pregnancy might affect neurodevelopment.

Teresa Reyes , a professor of pharmacology and systems physiology at the University of Cincinnati College of Medicine, told us via email that information was missing on the length of the rat pregnancies. “If the pregnancy length was significantly different, it could indicate that the litters were born prematurely, which confounds the interpretation of the findings,” she said.

In humans, COVID-19 vaccination during pregnancy  has not been shown  to increase preterm birth and may even protect against it.

She also said that information was missing on the weights of the pregnant rats, or dams, over time and their pups. “Significant differences in weight (e.g., vaccine exposed dams lost weight during the study) could indicate that the dams were severely ill in response to the vaccine, again confounding the interpretation of the study,” she said.

Coe said that he would have wanted “to replicate the findings rather than rush to publish on the basis of one experiment,” suggesting that both the authors of the paper and outside researchers should try to replicate the results.

And he expressed concern about the study’s statements that altered rat behaviors were “autism-like,” given that autism spectrum disorder is a “complex neurodevelopmental disorder.” 

Brian Lee , an associate professor of epidemiology and biostatistics at the Drexel University Dornsife School of Public Health who studies prenatal exposures and autism risk, told us via email that it is hard to diagnose autism in humans, let alone in rats. “It’s hard to read into some behavioral tests for a rat and imagine it translates 100% to an autism diagnosis in humans,” he said.

There also appeared to be issues with the study’s experimental design and statistical analysis.

For instance, studies of prenatal exposures need to account for something called “litter effects” — or the fact that the multiple offspring born in the same litter to the same animal mother might share characteristics.

“The authors did not describe any approach to address the potential for a litter confound which could skew the findings (e.g., one dam has a significantly different response, multiple pups are used from that litter, and this skews the findings),” Reyes said. 

Additionally, the authors wrote that they set out to determine whether maternal vaccination led to “any sex-specific neurobehavioral changes” — or ways in which sex and vaccination, in combination, affected the rats’ behavior.

The authors didn’t find evidence of such sex-specific effects on social behavior, but they nevertheless went on to compare social behavioral results from the male pups of vaccinated mothers versus unvaccinated mothers and highlighted the results — something Reyes said they shouldn’t have done. “By improperly using statistics to analyze the data, the conclusions are not valid,” she said. “It is impossible to verify the stated claims because statistics were used incorrectly.”

Evidence Indicates Maternal Vaccination Is Effective, Safe

A person’s likelihood of being autistic is  influenced  by a combination of genetics and other factors. These likely include older parental age and whether there are complications at a child’s birth,  including  extreme prematurity or very low birth weight. As we’ve written  previously , many lines of evidence contradict the idea — long spread by anti-vaccine groups — that childhood vaccines cause autism. 

Some theoretical concerns about vaccines given during pregnancy and autism are based on research  indicating  that infections during pregnancy might slightly increase the risk of a child later developing autism. “We know that immune activation can impact the way the brain develops, and sometimes that’s in adverse ways and yet we also know that the immune system is important in just normal brain development,” Bilbo said. 

But Bilbo said the body’s immune system reacts differently to a serious infection than it does to vaccination. A vaccine against a virus is designed to expose the body to just enough viral material to teach the immune system to recognize the infectious agent, should it encounter it later. “Dose matters, obviously,” Bilbo said. “It matters quite a bit.”

Studies in humans provide reassurance of recommended vaccines’ benefits and safety.

The Tdap vaccine — which protects against tetanus, diphtheria and pertussis, or  whooping cough  — is  recommended  during pregnancy to protect newborns until they are able to be vaccinated against pertussis themselves at two months of age. The CDC began to recommend the vaccine routinely in all pregnancies in  2012 , based on an uptick in pertussis, which can lead to death in very young babies.

A 2018  study  of children born in Kaiser Permanente Southern California hospitals between 2011 and 2014 found no increased risk of autism in those whose mothers had been vaccinated against Tdap during pregnancy.

Flu vaccines have  long  been  recommended  for pregnant people during flu season and reduce risks for both the mother and the baby. A 2020 Swedish  study  looking at vaccination against the 2009 pandemic swine flu found no link between vaccination during pregnancy and increased autism risk. 

A 2017  study , looking at children born in the Kaiser Permanente Northern California health system between 2000 and 2010, found no association overall between autism and flu vaccination during pregnancy. The researchers did find a “suggestion” of increased autism risk when mothers were vaccinated during the first trimester of pregnancy but said that statistical analyses indicated the “finding could be due to chance.”

In the case of COVID-19 vaccines, research  has not indicated  any negative impacts on pregnancy outcomes or on babies of vaccinated mothers. In fact, there’s some evidence maternal vaccination is protective against certain bad pregnancy outcomes, such as preterm birth and stillbirth.

A  study  published on Jan. 22 in JAMA Pediatrics followed around 4,200 children born to mothers who enrolled in the study between May 2020 and August 2021. At 18 months, scores on a developmental screening test did not differ between children whose mothers got COVID-19 vaccines during pregnancy versus those whose mothers didn’t.

The authors wrote that “these data suggest that maternal vaccination against COVID-19 during pregnancy was safe from the perspective of offspring neurodevelopment through 18 months of age.”

“It’s small and just 1 study, and of course more study is needed, but the findings are reassuring,” said Drexel’s Lee, who was not involved in the new study.

Coe emphasized the benefits of COVID-19 vaccination during pregnancy. “There are now many clinical studies that have demonstrated the benefits for safer pregnancy outcomes (as compared to the risk of an actual infection), as well as the reduced risk for young infants of getting a respiratory infection during the first 6 months of life,” he said.

“There is no known link between COVID-19 vaccines and the occurrence of autism spectrum disorder (ASD),” a Pfizer spokesperson told us in an email. “With hundreds of millions of doses of COVID-19 vaccines from BioNTech and Pfizer administered globally, the benefit-risk profile of our vaccines remains positive for all authorized indications/uses and age groups.”

Editor’s note: SciCheck’s articles providing accurate health information and correcting health misinformation are made possible by a grant from the Robert Wood Johnson Foundation. The foundation has no control over FactCheck.org’s editorial decisions, and the views expressed in our articles do not necessarily reflect the views of the foundation.

“ COVID-19 Vaccines While Pregnant or Breastfeeding .” CDC website. Updated 3 Nov 2023.

“ Getting Your COVID-19 Vaccine .” CDC website. Updated 23 Jan 2024.

Male, Victoria. “ COVID-19 vaccine safety in pregancy – table of studies .” Google Docs. Updated 8 Dec 2023.

Yandell, Kate. “ What RFK Jr. Gets Wrong About Autism .” FactCheck.org. 10 Aug 2023.

“ Autism and Vaccines .” CDC website. Updated 1 Dec 2021.

Plotkin, S. et al. “ Vaccines and Autism: A Tale of Shifting Hypotheses .” Clinical Infectious Diseases. Updated 15 Feb 2009.

Zerbo, Ousseny et al. “ Association Between Influenza Infection and Vaccination During Pregnancy and Risk of Autism Spectrum Disorder .” JAMA Pediatrics. 2 Jan 2017.

Ludvigsson, Jonas F. et al. “ Maternal Influenza A(H1N1) Immunization During Pregnancy and Risk for Autism Spectrum Disorder in Offspring: A Cohort Study .” Annals of Internal Medicine. 1 Sep 2020.

Becerra-Culqui, Tracy A. et al. “ Prenatal Tetanus, Diphtheria, Acellular Pertussis Vaccination and Autism Spectrum Disorder .” Pediatrics. Sep 2018.

“ Autism Spectrum Disorder .” National Institute of Neurological Disorders and Stroke. Updated 19 Dec 2023.

Jaswa, Eleni G. et al. “ In Utero Exposure to Maternal COVID-19 Vaccination and Offspring Neurodevelopment at 12 and 18 Months .” JAMA Pediatrics. 22 Jan 2024.

Erdogan, Mumin Alper et al. “ Prenatal Exposure to COVID-19 mRNA Vaccine BNT162b2 Induces Autism-Like Behaviors in Male Neonatal Rats: Insights into WNT and BDNF Signaling Perturbations .” Neurochemical Research. 10 Jan 2024.

Jackie | bootleg media (@bootlegmedia__). “ How does Anthony fauci sleep at night 😵‍💫… ” Instagram. 13 Jan 2024.

Athrappully, Naveen. “ COVID-19 Shots Linked to Autism in Vaccinated Rats: Study .” Epoch Times. 13 Jan 2024.

Candace Owens (@RealCandaceO). “ That’s because vaccines and autism have always been linked, which affected mothers have been trying to tell the general public for decades. … ” X. 13 Jan 2024.

HealthFreedomFlorida (@healthfreedomflorida). “ [no text] .” Instagram. 13 Jan 2024.

Ward, John. “ Maybe it wasn’t a good idea to recommend the jab to pregnant women. … ” Facebook. 19 Jan 2024.

shanna✨ scrunchy mama | organic humor | holistic. “ I wonder what they will find out next about this shot 🤔 … ” Instagram. 19 Jan 2024.

Nic🇺🇸* Former* Democrat turned outspoken critic. “ You alter your kids’ DNA w/ totally unnecessary & experimental meds … ” Instagram. 21 Jan 2024.

Unjected. “ We are the the true remaining ‘Control-Group’🧬 … ” Instagram. 23 Jan 2024.

Cops4Freedom. “ [no text] .” Instagram. 23 Jan 2024.

Sohn, Emily. “ How Rats Could Lead to Autism Drugs That Actually Work .” The Atlantic. 16 Mar 2017.

“ Rat Study Alleged to Link COVID-19 Vaccines to Autism Cannot Be Generalized to Humans and Contains Important Limitations .” Health Feedback. 18 Jan 2024.

CDC spokesperson. Email to FactCheck.org. 22 Jan 2024.

Bilbo, Staci. Interview with FactCheck.org. 18 Jan 2024.

Morris, Jeffrey S. Email to FactCheck.org. 25 Jan 2024.

Coe, Christopher. Email with FactCheck.org. 18 Jan 2024.

Reyes, Teresa. Email with FactCheck.org. 24 Jan 2024.

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“ What is Autism Spectrum Disorder? ” CDC website. Updated 9 Dec 2022.

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Vaccines and Autism: What Does the Research Tell Us?

Early Communication Support and Strategies

Where did the idea come from?

In the 1990’s, Andrew Wakefield and colleagues published a paper linking the MMR (measles, mumps, and rubella) vaccine to autism. However, the study only looked at 12 children. Additionally, after it was published, other researchers discovered that the paper contained false data. For example, the study stated that all of the children were developing typically before the vaccine when some already had delays. It also stated that some children showed symptoms days after the vaccine when records show the signs of autism started months later. Additionally, it was discovered that Wakefield had been paid by lawyers attempting to sue the vaccine manufacturer. Due to these findings, Wakefield lost his medical license and the journal retracted the paper. This means the journal no longer supported the study’s conclusions.

What does the research tell us?

The possibility of the link between vaccines and autism has been extensively studied. The scientific evidence overwhelming shows no connection between vaccines and autism or any other neurodevelopment disorder. In 2014, a study was conducted that combined the results from many studies to get a clear picture of what all the data show. In total, the researchers analyzed data from over 1 million children! They found no relationship between vaccines and autism. A 2019 paper looked at over 600,000 more children. It concluded that MMR vaccination does not “trigger autism” in children already at risk, such as those with a family history. In other words, vaccines do not cause autism and vaccines do not increase the risk of autism.

What does cause autism?

There is no single cause of autism. Research does suggest that different genetic and environmental factors can increase the chance that a child will develop autism. Genetic factors include times when a certain gene runs in a family or when a gene changes on its own during development in the womb. Examples of environmental factors include complications that happen during pregnancy and birth, such as a child being born very premature or having a very low birth weight. None of these situations cause autism on their own. Researchers are still trying to understand how different factors interact to cause autism.

What does this mean for my child and me?

Parents are the best advocates for their children. It is important to decide what is right for your individual child. It is also important to be knowledgeable about the latest scientific research so you can make informed decisions. Research tells us that vaccines are safe and effective ways to protect your child, and your community, from serious diseases.

Where can I learn more?

The center for disease control statement on vaccine safety.

https://www.cdc.gov/vaccinesafety/concerns/autism.html

The American Academy of Pediatrics Summary of Vaccine Research

https://www.aap.org/en-us/Documents/immunization_vaccine_studies.pdf

Scientific Journals

• Taylor, L.E., Swerdfeger, A.L., & Eslick, G.D. (2014). Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies, Vaccine. doi: 10.1016/j.vaccine.2014.04.085
• Hviid, A., Hansen, J.V., Frisch, M., & Melbye, M. (2019). Measles, mumps, rubella vaccination and autism: A nationwide cohort study. Annals of Internal Medicine . doi: 10.7326/M18-2101

Reputable websites by medical professionals

• An MD’s challenge of common concerns: http://www.howardisms.com/evidence-based-medicine/should-i-vaccinate-my-child/
• History of vaccines by a physician’s organization: https://www.historyofvaccines.org/content/articles/do-vaccines-cause-autism

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