Human papillomavirus vaccination of adult women and risk of autoimmune and neurological diseases.

BACKGROUND: Since 2006, human papillomavirus (HPV) vaccines have been introduced in many countries worldwide. Whilst safety studies have been reassuring, focus has been on the primary target group, the young adolescent girls. However, it is also important to evaluate safety in adult women where background disease rates and safety issues could differ significantly. OBJECTIVE: We took advantage of the unique Danish and Swedish nationwide healthcare registers 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 18-44 years of age. METHODS: We used Poisson regression to estimate RRs according to qHPV vaccination status with two-sided 95% confidence intervals (95% CIs). RESULTS: The study cohort comprised 3 126 790 women (1 195 865 [38%] Danish and 1 930 925 [62%] Swedish) followed for 16 386 459 person-years. Vaccine uptake of at least one dose of qHPV vaccine was 8% in the cohort: 18% amongst Danish women and 2% amongst Swedish. We identified seven adverse events with statistically significant increased risks following vaccination-Hashimoto's thyroiditis, coeliac disease, localized lupus erythematosus, pemphigus vulgaris, Addison's disease, Raynaud's disease and other encephalitis, myelitis or encephalomyelitis. After taking multiple testing into account and conducting self-controlled case series analyses, coeliac disease (RR 1.56 [95% confidence interval 1.29-1.89]) was the only remaining association. CONCLUSION: Unmasking of conditions at vaccination visits is a plausible explanation for the increased risk associated with qHPV in this study because coeliac disease is underdiagnosed in Scandinavian populations. 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.

Incidence of new-onset autoimmune disease in girls and women with pre-existing autoimmune disease after quadrivalent human papillomavirus vaccination: a cohort study.

OBJECTIVE: To assess whether quadrivalent human papillomavirus (qHPV) vaccination is associated with increased incidence of new-onset autoimmune disease in girls and women with pre-existing autoimmune disease. METHODS: This register-based open cohort study included all girls and women between 10 and 30 years of age in Sweden in 2006-2012 diagnosed with at least one of 49 prespecified autoimmune diseases (n = 70 265). Incidence rate ratios were estimated for new-onset autoimmune disease within 180 days of qHPV vaccination using Poisson regression adjusting for, country of birth, parental country of birth, parental income and parental education. RESULTS: A total of 70 265 girls and women had at least one of the 49 predefined autoimmune diseases; 16% of these individuals received at least one dose of qHPV vaccine. In unvaccinated girls and women, 5428 new-onset autoimmune diseases were observed during 245 807 person-years at a rate of 22.1 (95% CI 21.5-22.7) new events per 1000 person-years. In vaccinated girls and women, there were 124 new events during 7848 person-years at a rate of 15.8 (95% CI 13.2-18.8) per 1000 person-years. There was no increase in the incidence of new-onset autoimmune disease associated with qHPV vaccination during the risk period; on the contrary, we found a slightly reduced risk (incidence rate ratio 0.77, 95% CI 0.65-0.93). CONCLUSION: In this nationwide study, qHPV vaccination was not associated with increased incidence of new-onset autoimmune disease in girls and women with pre-existing autoimmune disease.