Vaccine Research

November 1, 2019

Using B cell receptor sequencing of human peripheral blood lymphocytes before and after measles viurs infection, researchers identified two immunological consequences from measles underlying immunosuppression: (i) incomplete reconstitution of the naïve B cell pool leading to immunological immaturity and (ii) compromised immune memory to previously encountered pathogens due to depletion of previously expanded B memory clones. Using a surrogate model of measles in ferrets, researchers found that measles infection causes changes in naïve and memory B lymphocyte diversity that persist after the resolution of clinical disease and thus contribute to compromised immunity to previous infections or vaccinations. This work highlights the importance of measles vaccination not only for the control of measles but also for the maintenance of herd immunity to other pathogens, which can be compromised after measles infection.

View study.

August 26, 2015
Sukumaran et al. Vaccine
The Vaccine Safety Datalink (VSD) is a collaboration between CDC and nine integrated healthcare systems that serves as a cornerstone of US post-licensure vaccine safety monitoring. Given concerns that potential differences between the insured VSD population and the US population could limit the generalizability of VSD study findings, this paper performed a comparison of the demographic characteristics between the two populations. The study authors concluded that the VSD population is representative of the general US population on several key demographic and socioeconomic variables.
View study.

June 1, 2014

Maglione et al. Pediatrics

Concerns about vaccine safety have led some parents to decline recommended vaccination of their children, leading to the resurgence of diseases. Reassurance of vaccine safety remains critical for population health. This study systematically reviewed the literature on the safety of routine vaccines recommended for children in the United States. The study authors found evidence that some vaccines are associated with serious adverse events; however, these events are extremely rare and must be weighed against the protective benefits that vaccines provide.

View study.

This page was developed by the National Academy of Sciences to provide scientific evidence behind the claim that “vaccines are safe.”

View

This page was developed by the National Academy of Sciences to provide scientific evidence behind the claim that “vaccines don’t cause autism.”

View

January 16, 2013

The Institute of Medicine (IOM) of the National Academies

This report is a very comprehensive examination of the immunization schedule. The IOM committee uncovered no evidence of major safety concerns associated with adherence to the childhood immunization schedule, which should help to reassure a diverse group of stakeholders.

Rather than exposing children to harm, following the complete childhood immunization schedule is strongly associated with reducing vaccine-preventable diseases.

View report.

August 25, 2011

The Institute of Medicine (IOM) of the National Academies

The Health Resources and Services Administration (HRSA) asked the IOM to assess the risk of specific adverse events associated with eight vaccines – varicella zoster, influenza (except 2009 H1N1) hepatitis B, HPV, MMR, hepatitis A, meningococcal, and those that contain tetanus, and evaluate the scientific evidence about the event–vaccine relationship.

Using epidemiologic and mechanistic evidence, the committee developed 158 causality conclusions and assigned each relationship between a vaccine and an adverse health problem to one of four categories of causation:

• Evidence convincingly supports a causal relationship
• Evidence favors acceptance of a causal relationship
• Evidence favors rejection of a causal relationship
• Evidence is inadequate to accept or reject a causal relationship

The IOM committee found that evidence convincingly supports a causal relationship between some vaccines and some adverse events—such as MMR, varicella zoster, influenza, hepatitis B, meningococcal, and tetanus-containing vaccines linked to anaphylaxis. Additionally, evidence favors rejection of five vaccine-adverse event relationships, including MMR vaccine and autism, and inactivated influenza vaccine and asthma episodes. However, for the majority of cases (135 vaccine-adverse event pairs), the evidence was inadequate to accept or reject a causal relationship. Overall, the IOM committee concluded that few health problems are caused by or clearly associated with vaccines.

View report brief.

May 17, 2004

The Institute of Medicine (IOM) of the National Academies

The Immunization Safety Review Committee (ISR) was a project within the Institute of Medicine (IOM) that addressed current and emerging vaccine-safety concerns. The committee provided independent, non-biased advice to vaccine policy-makers, as well as healthcare practitioners and the public.

This eighth and final report of the IOM’s ISR examines the hypothesis that vaccines, specifically the measles-mumps-rubella (MMR) vaccine and thimerosal-containing vaccines, are causally associated with autism. The committee reviewed the published and unpublished epidemiological studies regarding causality and studies of potential biologic mechanisms by which these immunizations might cause autism.

The committee concludes that the body of epidemiological evidence favors rejection of a causal relationship between the MMR vaccine and autism. The committee also concludes that the body of epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism. The committee further finds that potential biological mechanisms for vaccine-induced autism that have been generated to date are theoretical only.

The committee does not recommend a policy review of the current schedule and recommendations for the administration of either the MMR vaccine or thimerosal-containing vaccines. The committee recommends a public health response that fully supports an array of vaccine safety activities.

In addition, the committee recommends that available funding for autism research be channeled to the most promising areas. The committee makes additional recommendations regarding surveillance and epidemiological research, clinical studies, and communication related to these vaccine safety concerns.

View report.

October 6, 2003

The Institute of Medicine (IOM) of the National Academies

The Immunization Safety Review Committee (ISR) was a project within the Institute of Medicine (IOM) that addressed current and emerging vaccine-safety concerns. The committee provided independent, non-biased advice to vaccine policy-makers, as well as healthcare practitioners and the public.

The Immunization Safety Review committee reviewed the data on influenza vaccine and neurological conditions and concluded that the evidence favored acceptance of a causal relationship between the 1976 Swine Influenza vaccine and GBS in adults. The evidence about GBS for influenza vaccines of other years is not clear one way or the other (that is, the evidence is inadequate to accept or reject a causal relationship). The committee concluded that the evidence favored rejection of a causal relationship between influenza vaccines and exacerbation of multiple sclerosis. For the other neurological conditions studied, the committee concluded the evidence about the effects of influenza vaccine is inadequate to accept or reject a causal relationship. The committee also reviewed theories on how the influenza vaccine could damage the nervous system. The evidence was at most weak that the vaccine could act in humans in ways that could lead to these neurological problems.

View report.

February 20, 2002

The Institute of Medicine (IOM) of the National Academies

The Immunization Safety Review Committee (ISR) was a project within the Institute of Medicine (IOM) that addressed current and emerging vaccine-safety concerns. The committee provided independent, non-biased advice to vaccine policy-makers, as well as healthcare practitioners and the public.

The Immunization Safety Review committee reviewed the evidence regarding the hypothesis that multiple immunizations increase the risk for immune dysfunction, with a focus on evidence related to risk for infections, the autoimmune disease type I diabetes, and allergic disorders.

The committee found that evidence favors rejection of a causal relationship between multiple immunizations and increased risk for infections and for type I diabetes. They also found that epidemiological evidence regarding risk for allergic disease, particularly asthma, was inadequate to accept or reject a causal relationship. The committee recommended continued attention in the form of policy analysis, research, and communication strategy development to inform those concerned about these issues and to encourage parents to vaccinate their children.

View report.

October 1, 2001

The Institute of Medicine (IOM) of the National Academies

At the request of the Centers for Disease Control and Prevention and the National Institutes of Health, the Immunization Safety Review committee (ISR) was convened by the Institute of Medicine (IOM) of the National Academy of Sciences to examine whether or not the use of vaccines containing the preservative thimerosal can cause neurodevelopmental disorders.

In Immunization Safety Review: Thimerosal-Containing Vaccines and Neurodevelopmental Disorders, the IOM committee carefully examines this issue. The committee found no proof that vaccines with thimerosal do or do not cause the disorders of autism, attention deficit-hyperactivity disorder, and speech or language-delay.

View report.

Read Frequently Asked Questions: Thimerosal in Vaccines, which was created based on the committee’s findings.

August 23, 2001

The Institute of Medicine (IOM) of the National Academies

The Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) recognized the need for an independent group to carefully examine the hypothesized MMR-autism link and address other vaccine safety issues as well, in order to give some guidance to themselves, health care providers, researchers, and a concerned public. These agencies engaged the Institute of Medicine (IOM), which created the Immunization Safety Review Committee (ISR), a 15-member body of health professionals with wide-ranging expertise in areas relevant to the problem.

The committee reviewed the numerous research efforts on the MMR-autism hy­pothesis.“The evidence favors rejection of a causal relationship at the population level between MMR vaccine and autistic spectrum disorders,” the committee concludes in its report.“ A consistent body of epidemiological evidence shows no association at a popu­lation level between MMR and ASD,” the report says. Moreover, the committee can find no proven biological mechanisms that would explain such a relationship. Scientists have suggested some theories, but none have been demonstrated.

View Executive Summary from the report.

View report.

March 5, 2019
Hviid et al. Annals of Internal Medicine
This was a very large, nationwide cohort study of all children born in Denmark to Danish-born mothers from January 1, 1999 through  December 31, 2010. The study results strongly support that MMR vaccination does not increase the risk for autism, does not trigger autism in susceptible children, and is not associated with clustering of autism cases after vaccination. It adds to previous studies through significant additional statistical power, and by addressing hypotheses of susceptible subgroups and clustering of cases.
View study.

May 21, 2015

Jain et al. JAMA

In this large sample of privately insured children with older siblings, receipt of the MMR vaccine was not associated with increased risk of autism spectrum disorders (ASD), regardless of whether older siblings had ASD. These findings indicate no harmful association between MMR vaccine receipt and ASD even among children already at higher risk for ASD,

View study.

August 1, 2014

Maglione et al. Pediatrics

Concerns about vaccine safety have led some parents to decline recommended vaccination of their children, leading to the resurgence of diseases. Reassurance of vaccine safety remains critical for population health. This study systematically reviewed the literature on the safety of routine vaccines recommended for children in the United States. Study authors found evidence that some vaccines are associated with serious adverse events; however, these events are extremely rare and must be weighed against the protective benefits that vaccines provide.

View abstract.

View study.

May 9, 2014
Taylor et al. Vaccine
​After performing the meta-analysis of five cohort studies and five case-control studies, the authors of this research found no evidence of a link between vaccine receipt and risk of developing autism or autism spectrum disorders (ASDs). This conclusion stands when the authors looked at specific MMR vaccines, cumulative mercury dosage, and thimerosal exposure, and any connection to ASDs.

View study.

September 1, 2008

Hornig M et al. PLoS One

The presence of measles virus (MV) RNA in bowel tissue from children with autism spectrum disorders (ASD) and gastrointestinal (GI) disturbances was reported in 1998. Subsequent investigations found no associations between MV exposure and ASD but did not test for the presence of MV RNA in bowel or focus on children with ASD and GI disturbances. Failure to replicate the original study design may contribute to public concern with respect to the safety of the measles, mumps, and rubella (MMR) vaccine. The objective of this case-control study was to determine whether children with GI disturbances and autism are more likely than children with GI disturbances alone to have MV RNA and/or inflammation in bowel tissues and if autism and/or GI episode onset relate temporally to receipt of MMR. This study found strong evidence against association of autism with persistent MV RNA in the GI tract or MMR exposure. Autism with GI disturbances is associated with elevated rates of regression in language or other skills and may represent an endophenotype distinct from other ASD.

View study.

March 1, 2008

Baird et al. Archives of Disease in Childhood

The objective of this study was to test the hypothesis that measles vaccination was involved in the pathogenesis of ASD as evidenced by signs of a persistent measles infection or abnormally persistent immune response shown by circulating measles virus or raised antibody titres in MMR vaccinated children with ASD compared with controls. The study found no association between measles vaccination and ASD.

View study.

August 1, 2006

Fombonne et al. Pediatrics

The purpose of this work was to estimate the pervasive developmental disorder prevalence in Montreal, Canada, in cohorts born from 1987 to 1998 and evaluate the relationship of trends in pervasive developmental disorder rates with: (1) changes in cumulative exposure to ethylmercury (thimerosal) occurring through modifications in the immunization schedule of young children and (2) trends in measles-mumps-rubella (MMR) vaccination use rates and the introduction of a 2-MMR dosing schedule during the study period. The authors concluded that the prevalence of pervasive developmental disorder in Montreal was high, increasing in recent birth cohorts as found in most countries. Factors accounting for the increase include a broadening of diagnostic concepts and criteria, increased awareness and, therefore, better identification of children with pervasive developmental disorders in communities and epidemiologic surveys, and improved access to services. The study’s findings ruled out an association between pervasive developmental disorder and either high levels of ethylmercury exposure comparable with those experienced in the U.S. in the 1990s or 1- or 2-dose MMR vaccinations.

View study.

October 11, 2004

Smeeth et al. Lancet

Concern that measles-mumps-rubella (MMR) vaccination might cause autism has led to a fall in vaccine coverage. This study investigated whether MMR vaccination is associated with an increased risk of autism or other pervasive developmental disorders, and concluded that their findings suggest that MMR vaccination is not associated with an increased risk of pervasive developmental disorders.

View study.

July 1, 2003

Wilson et al. Archives of Pediatrics & Adolescent Medicine

The objective of this study was to systematically review the evidence for and against the existence of an association between autistic spectrum disorder (ASD) and the measles, mumps, and rubella (MMR) vaccine.The study authors concluded that current literature does not suggest an association between ASD and the MMR vaccine; however, limited epidemiological evidence exists to rule out a link between a rare variant form of ASD and the MMR vaccine. Given the real risks of not vaccinating and that the risks and existence of variant ASD remain theoretical, current policies should continue to advocate the use of the MMR vaccine.

View study.

November 1, 2002

Makela et al. Pediatrics

The possibility of adverse neurologic events has fueled much concern about the safety of measles-mumps-rubella (MMR) vaccinations. The available evidence concerning several of the postulated complications is controversial. The aim of this study was to assess whether an association prevails between MMR vaccination and encephalitis, aseptic meningitis, and autism. The study did not identify any association between MMR vaccination and encephalitis, aseptic meningitis, or autism.

View study.

October 1, 2001

Fombonne and Chakrabarti. Pediatrics

A link has been suggested between measles-mumps-rubella (MMR) vaccine and a form of autism that is a combination of developmental regression and gastrointestinal symptoms that occur shortly after immunization. This hypothesis has involved 3 separate claims: 1) that there is new phenotype of autism involving regression and gastrointestinal symptoms, 2) that this new variant is responsible for the alleged rise of autism rates, and 3) that this phenotype is associated with biological findings suggestive of the persistence of measles infection. We tested the first of these claims. If this new “autistic enterocolitis” syndrome had some validity, then 1 or several of the following 6 predictions should be supported by empirical data: 1) childhood disintegrative disorder has become more frequent, 2) the mean age of first parental concern for autistic children who are exposed to MMR is closer to the mean immunization age than in children who are not exposed to MMR, 3) regression in the development of children with autism has become more common in MMR-vaccinated children, 4) the age of onset for autistic children with regression clusters around the MMR immunization date and is different from that of autistic children without regression, 5) children with regressive autism have distinct symptom and severity profiles, and 6) regressive autism is associated with gastrointestinal symptoms and/or inflammatory bowel disorder. The study found no evidence to support a distinct syndrome of MMR-induced autism or of “autistic enterocolitis.” These results add to the recent accumulation of large-scale epidemiologic studies that all failed to support an association between MMR and autism at population level. When combined, the current findings do not argue for changes in current immunization programs and recommendations.

View study.

August 23, 2001

The Institute of Medicine (IOM) of the National Academies

The Centers for Disease Control and Prevention and the National Institutes of Health recognized the need for an independent group to carefully examine the hypothesized MMR-autism link and address other vaccine safety issues as well, in order to give some guidance to themselves, health care providers, researchers, and a concerned public. These agencies engaged the Institute of Medicine, which in turn appointed the Immunization Safety Review Committee, a 15-member body of health professionals with wide-ranging expertise in areas relevant to the problem. The committee reviewed the numerous research efforts on the MMR-autism hy­pothesis.“The evidence favors rejection of a causal relationship at the population level between MMR vaccine and autistic spectrum disorders,” the committee concludes in its report.“ A consistent body of epidemiological evidence shows no association at a popu­lation level between MMR and ASD,” the report says. Moreover, the committee can find no proven biological mechanisms that would explain such a relationship. Scientists have suggested some theories, but none have been demonstrated.

View report.

February 2015

Gadzinowski et al. Pediatric Infectious Diseases
The authors investigated the safety and immunogenicity of PCV-13 manufactured with or without polysorbate 80 (P80) in infants at 2, 3, 4 and 12 months of age. Immunogenicity and safety was similar for both formulations.

View Study

1998

Wiedermann et al. International Archives of Allergy and Immunology

Volunteers were vaccinated with three doses of yeast-derived hepatitis B vaccines at monthly intervals and compared with plasma derived vaccines. Before and four weeks after immunizations, blood samples were tested for presence of IgE or IgG antibodies against yeast antigens related to Saccharomyces cerevisiae and Candida albicans, respectively, as cross-reactivity exists between the two genera. No rise in IgE antibodies against Saccharomyces cerevisiae antigens nor in IgG antibodies against Candida albicans antigens was found. The study’s authors concluded that yeast proteins in recombinant hepatitis B vaccines do not cause type I or type III allergic reactions.

View Study

July 1, 1986

Zajac et al. Journal of Infection

The antigen used in the yeast-recombinant hepatitis B vaccine is derived from a culture of Saccharomyces cerevisiae (common baker’s yeast) and trace quantities of yeast protein exist within the product. As such, there is a theoretical concern that administration of a vaccine prepared in yeast might induce allergic reactions to yeast proteins. Researchers tested the sera of 133 persons before and after receipt of the recombinant vaccine for anti-yeast antibodies. One-hundred percent of individuals had anti-yeast IgG in both pre- and post-vaccination samples, presumably from exposure through eating bread. Levels fluctuated after receipt. Adverse reactions were not more frequent in persons with rises in yeast antibody titers.

View Study

October 11, 2018

Thompson et al. Clinical Infectious Diseases

This study examined influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza-associated hospitalizations during pregnancy. Researchers concluded that, between 2010 and 2016, influenza vaccines offered moderate protection against laboratory-confirmed influenza-associated hospitalizations during pregnancy.

View study.

Thompson et al. Vaccine

This study, conducted over multiple flu seasons, shows that getting a flu shot lessened the risk of severe influenza (flu) among adults, including reducing the risk of hospitalization and admission to the intensive care unit (ICU), and also lessened the severity of illness.

View study.

October 15, 2017

Arriola et al. Clinical Infectious Diseases

The study investigated the effect of influenza vaccination on disease severity in adults hospitalized with laboratory-confirmed influenza during 2013-14, a season in which vaccine viruses were antigenically similar to those circulating. The study authors demonstrated that despite vaccinated individuals became infected with influenza viruses, vaccination can reduce disease severity. This additional benefit of influenza vaccination on disease severity may be observed in future seasons when vaccine is shown to provide significant protection, especially among people aged ≥65 years.

View study.

April 2017

Flannery et al. Pediatrics

This study assessed whether influenza vaccination reduced the risk of influenza-associated death in children and adolescents. From July 2010 through June 2014, 358 laboratory-confirmed influenza-associated pediatric deaths were reported among children aged 6 months through 17 years. Vaccination status was determined for 291 deaths; 75 (26%) received vaccine before illness onset. Average vaccination coverage in survey cohorts was 48%. Overall VE against death was 65% (95% CI, 54% to 74%). Among 153 deaths in children with underlying high-risk medical conditions, 47 (31%) were vaccinated. VE among children with high-risk conditions was 51% (95% CI, 31% to 67%), compared with 65% (95% CI, 47% to 78%) among children without high-risk conditions. The study concluded that influenza vaccination was associated with reduced risk of laboratory-confirmed influenza-associated pediatric death.

View study.

April 1, 2016

Regan et al. Clinical Infectious Diseases

Mothers who received seasonal trivalent influenza vaccination (TIV) during pregnancy were significantly less likely to experience stillbirth compared with unvaccinated mothers. These results support the safety of seasonal influenza immunization during pregnancy and suggest a protective effect.

View study.

February 4, 2016

Oboho et al. The Journal of Infectious Diseases

Pregnant women are at higher risk for serious illness and complications, including death, from influenza. This study found that early initiation of influenza antiviral treatment to pregnant women hospitalized with influenza may reduce the length of stay in the hospital, especially among those with severe influenza. Influenza during pregnancy is associated with maternal and infant morbidity, and annual influenza vaccination is warranted.

View study.

October 13, 2015

Grijalva et al. JAMA

The goal of the study was to assess the association between influenza vaccination status and hospitalization for community-acquired laboratory-confirmed influenza pneumonia. The study found that among children and adults hospitalized with community-acquired pneumonia, those with laboratory-confirmed influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.

View study.

August 11, 2013

Griffin et al. The New England Journal of Medicine

The introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into the U.S. childhood immunization schedule in 2000 has substantially reduced the incidence of vaccine-serotype invasive pneumococcal disease in young children and in unvaccinated older children and adults. By 2004, hospitalizations associated with pneumonia from any cause had also declined markedly among young children. Because of concerns about increases in disease caused by nonvaccine serotypes, this study was used to determine whether the reduction in pneumonia-related hospitalizations among young children had been sustained through 2009 and whether such hospitalizations in older age groups had also declined. The study found that declines in hospitalizations for childhood pneumonia were sustained during the decade after the introduction of PCV7. Substantial reductions in hospitalizations for pneumonia among adults were also observed.

View study.

November 14, 2007

Roush and Murphy. JAMA

The objective of this study was to compare morbidity and mortality before and after widespread implementation of national vaccine recommendations for 13 vaccine-preventable diseases for which recommendations were in place prior to 2005. The study results showed a greater than 92% decline in cases and a 99% or greater decline in deaths due to diseases prevented by vaccines recommended before 1980 (diphtheria, mumps, pertussis, and tetanus). Endemic transmission of poliovirus and measles and rubella viruses has been eliminated in the United States; smallpox has been eradicated worldwide. Declines were 80% or greater for cases and deaths of most vaccine-preventable diseases targeted since 1980 including hepatitis A, acute hepatitis B, Hib, and varicella. Declines in cases and deaths of invasive S pneumoniae were 34% and 25%, respectively.

View study.

Weigand, MR et al. Emerging Infectious Diseases

April 2019

The CDC researchers characterized 170 complete genome assemblies from clinical Bordetella pertussis isolates representing geographic and temporal diversity in the United States. The researchers found that Bordetella pertussis, which causes pertussis (also known as whooping cough), has undergone genetic changes over time. This study data will aid research in developing an improved pertussis vaccine and pertussis control strategies.

View study.

Becerra-Culqui et al. Pediatrics

This study investigated the association between prenatal tetanus, diphtheria, acellular pertussis (Tdap) vaccination and autism spectrum disorder (ASD) risk in offspring. Study researchers concluded that prenatal Tdap vaccination was not associated with an increased ASD risk.

View study.

February 2018

Sukumaran et al. Pediatrics

This study found no association between vaccination during pregnancy and risk of infant hospitalization or death in the first 6 months of life. These findings support the safety of current recommendations for influenza and Tdap vaccination during pregnancy. This study’s findings contribute to the knowledge of the long-term safety of vaccination during pregnancy.

View study.

October 20, 2015

Sukumaran et al. JAMA

This study was conducted to determine whether receipt of Tdap vaccine during pregnancy administered in close intervals from prior tetanus-containing vaccinations is associated with acute adverse events in mothers and adverse birth outcomes in neonates. The study findings suggest that relatively recent receipt of a prior tetanus-containing vaccination does not increase risk after Tdap vaccination in pregnancy.

View study.

September 1, 2015

Skoff et al. Pediatrics

Pertussis is poorly controlled with the highest rates of morbidity and mortality among infants. Although the source of infant pertussis is often unknown, when identified, mothers have historically been the most common source of transmission. This study examined whether infant source of infection (SOI) has changed in the United States in light of the changing epidemiology. The study authors found, in contrast to previous studies, that data suggests that the most common source of transmission to infants is now siblings. While continued monitoring of SOIs will optimize pertussis prevention strategies, recommendations for vaccination during pregnancy should directly increase protection of infants, regardless of SOI.

View study.

October 6, 2015

Gdad et al. PNAS

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Some anecdotal reports suggest that ASD is related to exposure to ethyl mercury, in the form of the vaccine preservative, thimerosal, and/or receiving the measles, mumps, rubella (MMR) vaccine. Using infant rhesus macaques receiving thimerosalcontaining vaccines (TCVs) following the recommended pediatric vaccine schedules from the 1990s and 2008, researchers examined behavior, and neuropathology in three brain regions found to exhibit neuropathology in postmortem ASD brains. No neuronal cellular or protein changes in the cerebellum, hippocampus, or amygdala were observed in animals following the 1990s or 2008 vaccine schedules. Analysis of social behavior in juvenile animals indicated that there were no significant differences in negative behaviors between animals in the control and experimental groups. These data indicate that administration of TCVs and/or the MMR vaccine to rhesus macaques does not result in neuropathological abnormalities, or aberrant behaviors, like those observed in ASD.

View study.

Taylor et al. Vaccine

​After performing the meta-analysis of five cohort studies and five case-control studies, the authors of this research found no evidence of a link between vaccine receipt and risk of developing autism or autism spectrum disorders (ASDs). This conclusion stands when the authors looked at specific MMR vaccines, cumulative mercury dosage, and thimerosal exposure, and any connection to ASDs.

View study.

September 13, 2010

Price et al. Pediatrics

This study was designed to examine relationships between prenatal and infant ethylmercury exposure from thimerosal-containing vaccines and/or immunoglobulin preparations and ASD and 2 ASD subcategories: autistic disorder (AD) and ASD with regression. The study results found that prenatal and early-life exposure to ethylmercury from thimerosal-containing vaccines and immunoglobulin preparations was not related to increased risk of ASDs.

View study.

January 1, 2008

Schechter and Grether. Archives of General Psychiatry

Previous analyses of autism client data reported to the California Department of Developmental Services (DDS) have been interpreted as supporting the hypothesis that autism is caused by exposure to the preservative thimerosal, which contains ethylmercury. The exclusion of thimerosal from childhood vaccines in the United States was accelerated from 1999 to 2001. The Immunization Safety Review Committee of the Institute of Medicine has recommended surveillance of trends in autism as exposure to thimerosal during early childhood has decreased. The study looked to determine whether trends in DDS autism client data supported the hypothesis that thimerosal exposure is a primary cause of autism. The study authors found that the DDS data did not show any recent decrease in autism in California despite the exclusion of more than trace levels of thimerosal from nearly all childhood vaccines. The DDS data do not support the hypothesis that exposure to thimerosal during childhood is a primary cause of autism.

View study.

September 27, 2007

Thompson et al. New England Journal of Medicine

This study assessed the association between current neuropsychological performance and exposure to mercury during the prenatal period, the neonatal period (birth to 28 days), and the first 7 months of life. This study does not support a causal association between early exposure to mercury from thimerosal-containing vaccines and immune globulins and deficits in neuropsychological functioning at the age of 7 to 10 years.

View study.

May 16, 2007

Miles and Takahashi. American Journal of Medical Genetics

To determine whether mothers of children with autism are more likely to be Rh negative (Rh−) or to have received RhIg preserved with thimerosal, which is 49.6% ethyl mercury, we surveyed families of children with an autism spectrum disorder (ASD) ascertained through a University‐based autism clinic considered free of ascertainment biases related to type of autism or severity. Between 2004 and 2006, 305 mothers of 321 children with an ASD agreed to participate in a telephone interview. Analysis of complete records including the blood group status and RhIg exposure of 214 families showed that Rh− status is no higher in mothers of children with autism than in the general population, exposure to antepartum RhIg, preserved with thimerosal is no higher for children with autism and pregnancies are no more likely to be Rh incompatible. This was also true for autism subgroups defined by behavioral phenotype, gender, IQ, regressive onset, head circumference, dysmorphology, birth status, essential, or complex phenotype. These findings support the consensus that exposure to ethylmercury in thimerosal is not the cause of the increased prevalence of autism.

View study.

August 1, 2005

Burbacher et al. Environmental Health Perspectives

In this study the authors compared the systemic disposition and brain distribution of total and inorganic mercury in infant monkeys after thimerosal exposure with those exposed to MeHg.The results indicate that MeHg is not a suitable reference for risk assessment from exposure to thimerosal-derived Hg.

View study.

September 1, 2004

Hornig et al. Molecular Psychiatry

This study was designed to determine whether vaccination with a thimerosal-containing vaccine is associated with development of autism.The study results do not support a causal relationship between childhood vaccination with thimerosal-containing vaccines and development of autistic-spectrum disorders.

View study.

September 1, 2004

Heron et al. Pediatrics

The aim of this research was to test in a large United Kingdom population-based cohort whether there is any evidence to justify concerns about thimerosal use in vaccines. The study authors could find no convincing evidence that early exposure to thimerosal had any deleterious effect on neurologic or psychological outcome.

View study.

November 1, 2003

Verstraeten et al. Pediatrics

This study attempted to assess the possible toxicity of thimerosal-containing vaccines (TCVs) among infants. A 2-phased retrospective cohort study was conducted using computerized health maintenance organization (HMO) databases. No consistent significant associations were found between TCVs and neurodevelopmental outcomes.

View study.

October 1, 2003

Hviid et al. Journal of the American Medical Association (JAMA)

This was a population-based cohort study of all children born in Denmark from January 1, 1990, until December 31, 1996 (N = 467 450) comparing children vaccinated with a thimerosal-containing vaccine with children vaccinated with a thimerosal-free formulation of the same vaccine. The study authors attempted to determine whether vaccination with a thimerosal-containing vaccine is associated with development of autism, and the study results do not support a causal relationship between childhood vaccination with thimerosal-containing vaccines and development of autistic-spectrum disorders.

View study.

September 1, 2003

Madsen et al. Pediatrics

It has been suggested that thimerosal is a risk factor for the development of autism. The authors examined whether discontinuing the use of thimerosal-containing vaccines in Denmark led to a decrease in the incidence of autism. The study found that the discontinuation of thimerosal-containing vaccines in Denmark in 1992 was followed by an increase in the incidence of autism. Their ecological data do not support a correlation between thimerosal-containing vaccines and the incidence of autism.

View study.

August 1, 2003

Stehr-Green et al. American Journal of Preventive Medicine

This study compared the prevalence/incidence of autism in California, Sweden, and Denmark with average exposures to thimerosal-containing vaccines between the mid-1980s through the late-1990s. The study authors condcluded that the body of existing data, including the ecologic data presented herein, is not consistent with the hypothesis that increased exposure to thimerosal-containing vaccines is responsible.

View study.

March 2003

Nelson and Bauman. Pediatrics

This review examined whether, according to available evidence, thimerosal is a probable cause of autism. Commentary authors stated “On the basis of current evidence, we consider it improbable that thimerosal and autism are linked.”

View commentary.

November 1, 2002

Pichichero et al. The Lancet

The study aimed to measure concentrations of mercury in blood, urine, and stools of infants who received vaccines containing thiomersal. The study concluded that administration of vaccines containing thiomersal does not seem to raise blood concentrations of mercury above safe values in infants. Ethylmercury seems to be eliminated from blood rapidly via the stools after parenteral administration of thiomersal in vaccines.

View study.

December 2019

Bi et al. Human Vaccines and Immunotherapy

In this randomized study, the authors evaluated the efficacy and safety of an adjuvanted-HPV 16/18 vaccine in more than 32,000 Finnish adolescent males and females over a 6.5-year period by comparing those who received HPV vaccine to those who received hepatitis B vaccine. The HPV vaccine adjuvant was composed of monophosphoryl-lipid A plus aluminum salts. The incidence of new-onset autoimmune diseases was similar in both vaccine groups. Similarly, those receiving HPV vaccine during pregnancy did not have an increased risk for spontaneous abortion or congenital anomalies.

View Study

2018

Frisch et al. International Journal of Epidemiology

The authors investigated the association of quadrivalent HPV (qHPV) vaccination and the risk of 39 autoimmune diseases, 12 neurological diseases, or venous thromboembolism over a 10-year period in more than 7,000 Danish boys who received at least one dose of qHPV vaccination at the age of 10 to 17 years by comparing them to more than 560,000 boys who did not receive the vaccine. Receipt of qHPV in boys aged 10-17 years was not associated with an elevated risk of autoimmune diseases, neurological diseases, or venous thromboembolism.

View study.

2018

Liu et al. Canadian Medical Association Journal

The authors assessed the risk of autoimmune disorders following quadrivalent HPV (qHPV) vaccine among more than 290,000 eighth-grade girls eligible for Ontario’s school-based HPV vaccination program. There was no significant risk for developing an autoimmune disorder following HPV vaccination and the association was unchanged by a history of immune-mediated disorders and time since vaccination.

View study.

2017

Grimaldi-Bensouda et al. Journal of Autoimmunity

The authors found that HPV vaccine did not increase the risk of autoimmune diseases in females 11 to 25 years of age. Autoimmune diseases included central demyelination, multiple sclerosis, connective tissue disease, Guillain-Barré syndrome, type 1 diabetes, autoimmune thyroiditis, and idiopathic thrombocytopenic purpura.

View study.

2016
Gronlund et al. Journal of Internal Medicine
The authors assessed whether HPV vaccination was associated with an increased incidence of new-onset autoimmune disease in more than 70,000 girls and women (10-30 years of age) with pre-existing autoimmune diseases. They found that HPV vaccination did not increase the risk of other autoimmune diseases in this patient population.
View study.