The quadrivalent human papillomavirus (HPV4) vaccine has been shown to be over 99% effective at preventing pre-cancerous lesions associated with HPV.¹ However, there have been case reports of autoimmune disorders and a (now retracted) news story in 2015 in Canada that was thought to have undermined confidence in the use of the vaccine.² A large Canadian retrospective cohort study has sought to assess the risk of autoimmune disorders in girls after HPV4 vaccination.¹

The study, which used the state of Ontario’s administrative health and vaccination databases from 2007 to …