Study finds no link between HPV vaccination and risk of autoimmune disorders
Girls aged 12 to 17 years are not more likely to be diagnosed with an autoimmune disorder after receiving the human papillomavirus (HPV4) vaccination, according to a new study from the Institute for Clinical Evaluative Sciences (ICES).
The study published today in CMAJ builds on previous international studies that have found the HPV vaccines to be safe. The researchers wanted to determine whether the HPV4 vaccination triggered autoimmune conditions such as lupus, rheumatoid arthritis, type 1 diabetes and multiple sclerosis. The researchers studied this link because isolated cases of autoimmune disorders following HPV4 vaccination had been reported but had not been confirmed in studies.
“Despite demonstrated effectiveness in real-world settings, concerns continue to persist regarding the safety of the HPV4 vaccine. In light of these concerns, we wanted to study the safety of the HPV4 vaccine since it was being offered free to all grade 8 girls in Ontario during the study period,” says Dr. Linda Lévesque, principal investigator of the Grade 8 HPV Vaccine research program.
Using secure patient health records housed at ICES, the researchers studied more than 290,000 girls aged 12–17 years who were eligible for HPV4 vaccination between 2007 and 2013. The researchers then compared the rate of autoimmune disorders diagnosed seven to 60 days after vaccination to the rate of diagnosis that occurred at any other time.
“We compared vaccinated girls to themselves over time to minimize the risk of bias and divided their follow-up time into ‘exposed’ and ‘unexposed’ time intervals. This method, called the self-controlled case series is considered the gold standard for vaccine safety research.” says Erin Liu, lead author on the study.
The researchers found that of the 290,939 girls eligible for the Grade 8 HPV vaccination program between 2007 and 2013, a total of 180,819 (62.2 per cent) received at least one dose of the HPV4 vaccine, with most receiving all three doses (81.8 per cent), and 110 120 (37.8 per cent) were unvaccinated. Among 681 cases of autoimmune disorders diagnosed in vaccinated girls, 77 (11.3 per cent) occurred seven to 60 days after HPV4 vaccination. However, this is consistent with the rate of autoimmune disorders diagnosed in this age group.
Human papillomavirus (HPV) is the most common sexually transmitted infection globally, affecting 50 to 75 per cent of all sexually active people. The HPV4 vaccine (also known as Gardasil) protects against four types of HPV shown to cause cervical cancer and anogenital warts. The vaccine has been available since 2006.
“Quadrivalent human papillomavirus vaccine in teenage girls and the risk of autoimmune disorders: the Ontario Grade 8 HPV Vaccine Cohort Study,” was published today in CMAJ.
Author block: Liu EY, Smith LM, Ellis AK, Whitaker H, Law B, Kwong JC, Farrington P, Lévesque LE
The Institute for Clinical Evaluative Sciences (ICES) is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario
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