Case reports have prompted concern about a possible link between the quadrivalent human papillomavirus (qHPV) vaccine and development of multiple sclerosis (MS) and other demyelinating diseases.
This link was investigated in a cohort of nearly 4 million girls and women in Denmark and Sweden who were followed up from 2006 until 2013, nearly 800,000 of whom received the qHPV vaccine. The incidence of demyelinating diseases did not differ significantly between vaccinated and unvaccinated individuals, with adjusted rate ratios of 0.90 (95% confidence interval 0.70–1.15) for MS and 1.00 (95% CI 0.80–1.26) for other demyelinating diseases.
“Our study adds to the body of data that support a favourable overall safety profile of the qHPV vaccine,” write the study authors in JAMA
 (online, 6 January 2015).