The epidemiological profile of ASIA syndrome after HPV vaccination: an evaluation based on the Vaccine Adverse Event Reporting Systems

The term "ASIA-Autoimmune/inflammatory Syndrome Induced by Adjuvants" describes an umbrella of clinical conditions sharing similar signs or symptoms, including post-vaccination phenomena. No information is available on the epidemiology of the ASIA syndrome, especially following HPV vaccination. We carried out an analysis of the VAERS database to retrieve all cases of suspected ASIA syndrome according to the Shoenfeld and Agmon-Levin's guideline for the diagnosis. After causality assessment and case validation, 2,207 cases were considered probably or possibly related to vaccination. These represent the largest ASIA cohort ever reported and allowed us to estimate epidemiological and clinical characteristic of this syndrome. The commonest clinical manifestation observed were pyrexia (58 %), myalgia (27 %) and arthralgia or arthritis (19 %), and the estimated reporting rate was of 3.6 cases per 100,000 doses of HPV vaccine distributed (95 % CI 3.4-3.7). This study presents the first systematic estimation of ASIA incidence and expands the knowledge on this pathology. Further analyses are needed to identify genetic and non-genetic risk factors for ASIA syndrome.