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

ObjectiveTo 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. MethodsThis 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. ResultsA 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). ConclusionIn 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.