No increased risk of Guillain-Barré syndrome after human papilloma virus vaccine: A self-controlled case-series study in England

Objective To investigate the risk of Guillain-Barré syndrome (GBS) after human papilloma virus (HPV) vaccine given to 12–18 year old girls in England. Methods Hospital Episode Statistics (HES) were searched using data to March 2016 to identify incident cases of GBS in female patients aged from 11 to 20 years eligible to have received the HPV vaccine since its introduction as a 3 dose schedule in September 2008. Diagnosis was confirmed by the case's general practitioner (GP) who also provided HPV vaccination dates. The risk of admission within 3 months (primary risk window) 6 and 12 months of any dose was assessed using the self-controlled case-series (SCCS) method in vaccinated girls with age, season and time-period adjustment. The risk before and after the change in 2012 from bivalent vaccine to quadrivalent vaccine was also assessed. Results A total 244 episodes were initially identified which reduced to 101 episodes in 100 girls when just including cases where the GP could be contacted, at least one vaccine dose was given, and GBS was confirmed or classed as probable. Nine, 14 and 24 GBS admissions occurred within 3, 6, 12 months of a dose respectively. The relative incidence (RI) for the 3 month risk period was 1.04 (95% confidence interval 0.47–2.28), for the 6 month period 0.83 (0.41–1.69) and for the 12 month period 1.10 (0.57–2.14). When restricting to 79 confirmed cases the RI in the 3 month risk period was 1.26 (0.55–2.92) and the RI 1.61 (0.39–6.54) for quadrivalent vaccine compared to 0.84 (0.30–2.34) for bivalent. Conclusion We found no evidence of an increased risk of GBS following HPV vaccination in England and, based on the upper end of the 95% CI for the RI and the number of HPV vaccine doses given in England, can exclude a risk of about 1 per million doses.