Suspected Adverse Effects After Human Papillomavirus Vaccination: A Temporal Relationship Between Vaccine Administration and the Appearance of Symptoms in Japan

Introduction In Japan, after receiving human papillomavirus vaccination, a significant number of adolescent girls experienced various symptoms, the vast majority of which have been ascribed to chronic regional pain syndrome, orthostatic intolerance, and/or cognitive dysfunction. However, a causal link has not been established between human papillomavirus vaccination and the development of these symptoms. Objective The aim of this study was to clarify the temporal relationship between human papillomavirus vaccination and the appearance of post-vaccination symptoms. Methods Between June 2013 and December 2016, we examined symptoms and objective findings in 163 female patients who had received human papillomavirus vaccination. We used newly defined diagnostic criteria for accurate inclusion of patients who experienced adverse symptoms after human papillomavirus vaccination; these diagnostic criteria were created for this study, and thus their validity and reliability have not been established. Results Overall, 43 female patients were excluded. Among the remaining 120 patients, 30 were diagnosed as having definite vaccine-related symptoms, and 42 were diagnosed as probable. Among these 72 patients, the age at initial vaccination ranged from 11 to 19 years (average 13.6 ± 1.6 years), and the age at appearance of symptoms ranged from 12 to 20 years (average 14.4 ± 1.7 years). The patients received the initial human papillomavirus vaccine injection between May 2010 and April 2013. The first affected girl developed symptoms in October 2010, and the last two affected girls developed symptoms in October 2015. The time to onset after the first vaccine dose ranged from 1 to 1532 days (average 319.7 ± 349.3 days). Conclusions The period of human papillomavirus vaccination considerably overlapped with that of unique post-vaccination symptom development. Based on these sequential events, it is suggested that human papillomavirus vaccination is related to the transiently high prevalence of the previously mentioned symptoms including chronic regional pain syndrome and autonomic and cognitive dysfunctions in the vaccinated patients.