Kingston, Ontario—Girls receiving quadrivalent human papillomavirus (HPV4) vaccinations appear to have no greater risk of developing autoimmune disorders, a new study finds.

The research published in CMAJ (Canadian Medical Association Journal) adds to evidence that the vaccine is safe, according to study authors led by researchers from Queens University.

“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 HPV4 vaccination since it was being offered free to all grade 8 girls in Ontario through school-based clinics,” explained Jeffrey Kwong, MS, MSc, a senior scientist at the Institute for Clinical Evaluative Sciences (ICES) and at Public Health Ontario.

Seeking to determine if the HPV4 vaccination, which is effective at protecting against 90% of the strains that cause cervical and anal cancer, triggered autoimmune conditions such as lupus, rheumatoid arthritis, type 1 diabetes, and multiple sclerosis, researchers analyzed data on 290,939 girls aged 12 to 17 years in Ontario who were eligible for vaccination between 2007 and 2013.

The study team found 681 diagnosed cases of autoimmune disorders between 1 week and 2 months after vaccination in 180,819 girls who received the HPV4 (Gardasil and Merck) vaccination in school-based clinics. Study authors emphasize that is consistent with the general rate of diagnosed cases in this age group.

Results show a rate ratio of 1.12, and the association was unchanged by a history of immune-mediated disorders and time since vaccination. Researchers note that exploratory analyses of individual autoimmune disorders found no significant risks, including for Bell palsy (n = 65; rate ratio 1.73, 95% CI 0.77–3.89), optic neuritis (n = 67; rate ratio 1.57, 95% CI 0.74–3.33) and Grave’s disease (n = 47; rate ratio 1.55, 95% CI 0.92–2.63).

“These findings add to the body of evidence on the safety of the HPV4 vaccine and should reassure parents and health care providers,” added coauthor Linda Lévesque, BScPhm, MSc, PhD, of the University of Toronto.

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