Historical Vaccine Safety Concerns

There is solid medical and scientific evidence that the benefits of vaccines far outweigh the risks. Despite this, there have been concerns about the safety of vaccines for as long as they have been available in the U.S. This page will explain past vaccine safety concerns, how they have been resolved, and what we have learned.

In 1955, some batches of polio vaccine given to the public contained live polio virus, even though they had passed required safety testing. Over 250 cases of polio were attributed to vaccines produced by one company: Cutter Laboratories. This case, which came to be known as the Cutter Incident, resulted in many cases of paralysis. The vaccine was recalled as soon as cases of polio were detected.

The Cutter Incident was a defining moment in the history of vaccine manufacturing and government oversight of vaccines, and led to the creation of a better system of regulating vaccines.  After the government improved this process and increased oversight, polio vaccinations resumed in the fall of 1955.

At the time, there was no system in place to compensate people who might have been harmed by a vaccine. Today we have the National Vaccine Injury Compensation Programexternal icon (VICP), which uses scientific evidence to determine whether a vaccine might be the cause of an illness or injury, and provides compensation to individuals found to have been harmed by a vaccine. The VICP remains a model method for ensuring that all persons harmed by vaccines are compensated quickly and fairly, while also protecting companies that make lifesaving products from financially unsustainable liability claims through the tort system.

For more information, see Food and Drug Administration (FDA)’s Science and the Regulation of Biological Productsexternal icon page.

From 1955 to 1963, an estimated 10-30% of polio vaccines administered in the US were contaminated with simian virus 40 (SV40). The virus came from monkey kidney cell cultures used to make polio vaccines at that time. Most of the contamination was in the inactivated polio vaccine (IPV), but it was also found in oral polio vaccine (OPV).  After the contamination was discovered, the U.S. government established testing requirements to verify that all new lots of polio vaccines were free of SV40.

Because of research done with SV40 in animal models, there has been some concern that the virus could cause cancer in humans. However, most studies looking at the relationship between SV40 and cancers are reassuring, finding no causal association between receipt of SV40-contaminated polio vaccine and development of cancer.

No vaccines used today contain SV40 virus.

For more information, see

  1. Vaccine Safety and Your Child: Separating Fact from Fiction pdf icon[PDF – 1.53 MB]external icon.
  2. Immunization Safety Review: SV40 Contamination of Polio Vaccine and Cancer.external icon

Additional references

Petricciani J, Sheets R, Griffiths E, Knezevic I. Adventitious agents in viral vaccines: Lessons learned from 4 case studies. Biologicals. 2014 Sep;42(5):223-36. https://www.ncbi.nlm.nih.gov/pubmed/25135887external icon

Mohammad-Taheri Z, Nadji SA, Raisi F, Mohammadi F, Bahadori M, Mark EJ. No association between simian virus 40 and diffuse malignant mesothelioma of the pleura in Iranian patients: a molecular and epidemiologic case-control study of 60 patients. Am J Ind Med. 2013 Oct;56(10):1221-5. https://www.ncbi.nlm.nih.gov/pubmed/23828611external icon

Eom M, Abdul-Ghafar J, Park SM, Han JH, Hong SW, Kwon KY, Ko ES, Kim L, Kim WS, Ha SY, Lee KY, Lee CH, Yoon HK, Choi YD, Chung MJ, Jung SH. No detection of simian virus 40 in malignant mesothelioma in Korea. Korean J Pathol. 2013 Apr;47(2):124-9. https://www.ncbi.nlm.nih.gov/pubmed/23667371external icon

Qi F, Carbone M, Yang H, Gaudino G. Simian virus 40 transformation, malignant mesothelioma and brain tumors. Expert Rev Respir Med. 2011 Oct;5(5):683-97. https://www.ncbi.nlm.nih.gov/pubmed/21955238external icon

Hmeljak J, Kern I, Cör A. No implication of Simian virus 40 in pathogenesis of malignant pleural mesothelioma in Slovenia. Tumori. 2010 Sep-Oct;96(5):667-73.https://www.ncbi.nlm.nih.gov/pubmed/21302609external icon

Lundstig A, Dejmek A, Eklund C, Filinic I, Dillner J. No detection of SV40 DNA in mesothelioma tissues from a high incidence area in Sweden. Anticancer Res. 2007 Nov-Dec;27(6B):4159-61. https://www.ncbi.nlm.nih.gov/pubmed/18225586external icon

Poulin DL, DeCaprio JA. Is there a role for SV40 in human cancer? J Clin Oncol. 2006 Sep 10;24(26):4356-65. Review. https://www.ncbi.nlm.nih.gov/pubmed/16963733external icon

Thu GO, Hem LY, Hansen S, Møller B, Norstein J, Nøkleby H, Grotmol T. Is there an association between SV40 contaminated polio vaccine and lymphoproliferative disorders? An age-period-cohort analysis on Norwegian data from 1953 to 1997. Int J Cancer. 2006 Apr 15;118(8):2035-9. https://www.ncbi.nlm.nih.gov/pubmed/16287082external icon

Dang-Tan T, Mahmud SM, Puntoni R, Franco EL. Polio vaccines, Simian Virus 40, and human cancer: the epidemiologic evidence for a causal association. Oncogene. 2004 Aug 23;23(38):6535-40. https://www.ncbi.nlm.nih.gov/pubmed/15322523external icon

In 1976 there was a small increased risk of a serious neurological disorder called Guillain-Barré Syndrome (GBS) following vaccination with a swine flu vaccine. The increased risk was approximately 1 additional case of GBS for every 100,000 people who got the swine flu vaccine. When over 40 million people were vaccinated against swine flu, federal health officials decided that the possibility of an association of GBS with the vaccine, however small, necessitated stopping immunization until the issue could be explored.

The Institute of Medicine (IOM) conducted a thorough scientific reviewexternal icon of this issue in 2003 and concluded that people who received the 1976 swine influenza vaccine had an increased risk for developing GBS. Scientists have multiple theories on why this increased risk may have occurred, but the exact reason for this association remains unknown.

Today, CDC continually monitors the safety of seasonal and pandemic flu vaccines, and any possible safety problems are discussed by the Advisory Committee on Immunization Practices.  Vaccination is the best way to prevent flu infection and its complications, and having safe and effective flu vaccines is extremely important.

For more information, see Guillain-Barré Syndrome and Influenza Vaccine or the Emerging Infectious Diseases Reflections on the 1976 Swine Flu Vaccination Program article.

In 1998, some research caused concern that hepatitis B vaccination might be linked with multiple sclerosis (MS), a progressive nerve disease. However, this link has not been found in the large body of research that has been done since that time.  In 2002, the Institute of Medicine thoroughly reviewed all available evidence and published a reportexternal icon.  In this thorough review, the IOM committee concluded that there is no link between hepatitis B vaccination and MS.

For more information, see the Hepatitis B Vaccine and Multiple Sclerosis page.

In 1998, the FDA approved RotaShield vaccine, the first vaccine to prevent rotavirus gastroenteritis. Shortly after it was licensed, some infants developed intussusception (rare type of bowel obstruction that occurs when the bowel folds in on itself) after being vaccinated. At first, it was not clear if the vaccine or some other factor was causing the bowel obstructions. CDC quickly recommended that use of the vaccine be suspended and immediately started two emergency investigations to find out if receiving RotaShield vaccine was causing some of the cases of intussusception.

The results of the investigations showed that RotaShield vaccine caused intussusception in some healthy infants younger than 12 months of age who normally would be at low risk for this condition.

The Advisory Committee on Immunization Practices (ACIP) withdrew its recommendation to vaccinate infants with RotaShield® vaccine, and the manufacturer voluntarily withdrew RotaShield from the market in October 1999.

For more information, see the Rotavirus Vaccine (RotaShield) and Intussusception page.

There were concerns that the meningococcal vaccine Menactra caused a serious neurological disorder called Guillain-Barré Syndrome (GBS). Between 2005 and 2008, there were a number of youth who reported GBS after receiving Menactra. However, to investigate whether GBS was caused by the vaccine or was coincidental with vaccination, two large studies were conducted, with a combined total of over 2 million vaccinated adolescents.  The results of these studies showed that there was no link between Menactra and GBS.

For more information, see the GBS and Menactra Meningococcal Vaccine page.

In 2007, Merck & Company, Inc. voluntarily recalled 1.2 million doses of Haemophilus influenzae type b (Hib) vaccines due to concerns about potential contamination with bacteria called B. cereus. The recall was a precaution, and after careful review, no evidence of B. cereus infection was found in recipients of recalled Hib vaccines.

For more information, see the Safety Report on Recalled Hib Vaccines page.

An increased risk of narcolepsy (a chronic sleep disorder) was found following vaccination with Pandemrix, a monovalent 2009 H1N1 influenza vaccine that was used in several European countries during the H1N1 influenza pandemic. This risk was initially found in Finland, and then some other European countries also detected an association.

Pandemrix is manufactured by GlaxoSmithKline in Europe and was specifically produced for pandemic 2009 H1N1 influenza. Pandemrix was never licensed for use in the United States.

In 2014, CDC published a study on the association between 2009 H1N1 influenza vaccines, 2010/2011 seasonal influenza vaccines, and narcolepsy. The study found that vaccination was not associated with an increased risk for narcolepsy.

For more information, see the Narcolepsy Following Pandemrix Influenza Vaccination in Europe page.

Porcine circovirus (PCV) is a common virus found in pigs. In 2010, it was discovered that both rotavirus vaccines licensed in the U.S.- Rotarix and RotaTeq- contained PCV type 1. PCV1 is not known to cause disease in animals or humans. In fact, PCV is common in healthy pigs, and humans are routinely exposed to the virus by eating pork. Safety monitoring of both vaccines has not shown any reason for concern about PCV.

For more information, see the World Health Organization’s Questions and Answers Relating to Finding of Porcine Circoviruses in Rotavirus Vaccines pdf icon[PDF – 53 KB]external icon page.

In 2013, Merck & Company, Inc. recalled one batch of Gardasil, a human papillomavirus (HPV) vaccine. The recall was a precaution following an error in the manufacturing process. The company had concerns that a small number of vials might have contained glass particles due to breakage.  No health problems were reported relating to this recall other than known side effects that can result from any vaccination, like arm redness and soreness where the shot was given.

For more information, see the Voluntary Recall of One Lot of Gardasil HPV Vaccine page or CDC’s Gardasil Recall Media Statement.