No “safety issues of concern” were found in a comprehensive study of the safety of human papillomavirus (HPV) vaccine in adult women.
The study published in the Journal of Internal Medicine involved more than 3 million Danish and Swedish adult women and found no link between the HPV virus and 44 serious chronic diseases. Even though an increased risk of developing celiac disease was identified among the Danish cohort, study authors suggested that could be due to “unmasking” of conditions at medical visits to receive the vaccine.
Since 2006, HPV vaccines have been introduced around the world, but safety studies have focused on the primary target group, young adolescent girls. Some adult women, however, also receive the vaccine and researchers from the Statens Serum Institut sought to evaluate safety in that group, where background disease rates and safety issues could differ significantly.
The study team used nationwide healthcare registers from the two countries to conduct a cohort study comparing incidence rate ratios (RRs) of 45 preselected serious chronic diseases in quadrivalent HPV (qHPV)-vaccinated and qHPV-unvaccinated adult women from age 18 to 44 years.
Included in the study cohort were 3.1 million Danish women and 1.9 million Swedish women followed for more than 16 million person-years. At least one dose of qHPV vaccine had been received by 8% of the participants—18% of the Danish women and 2% of the Swedish women.
Researchers identified seven potential adverse events with statistically significant increased risks following some types of vaccination: Hashimoto’s thyroiditis, celiac disease, localized lupus erythematosus, pemphigus vulgaris, Addison’s disease, Raynaud’s disease, and other encephalitis, myelitis or encephalomyelitis.
After analysis, celiac disease with an RR of 1.56 was the only association identified.
“Unmasking of conditions at vaccination visits is a plausible explanation for the increased risk associated with qHPV in this study because celiac disease is underdiagnosed in Scandinavian populations” study authors explain, adding, “In conclusion, our study of serious adverse event rates in qHPV-vaccinated and qHPV-unvaccinated adult women 18–44 years of age did not raise any safety issues of concern.”
“This is the most comprehensive study of HPV vaccination safety in adult women to date. It is not unreasonable to expect different safety concerns in adult women compared with young girls, and our study is an important supplement to the safety studies in young girls,” emphasized lead author Anders Hviid, MSc, of the Statens Serum Institut in Denmark.