Adverse Events of Interest Vary by Influenza Vaccine Type and Brand: Sentinel Network Study of Eight Seasons (2010-2018)

Abstract

Background: There are a range of types of influenza vaccines: Inactivated vaccines vary by number of component virus strains, they are trivalent (TIV) or quadrivalent (QIV) and are given by injection. Live attenuated influenza vaccine (LAIV) is given intranasal. Monitoring of adverse events of interests (AEIs) following influenza vaccination is recommended by the European Medicines Agency (EMA) to monitor common and detect infrequent but important adverse events of interest (AEI). Methods: A retrospective cohort study of the computerised medical record data from the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) sentinel network database 2010-2018 (N=848,375). We extracted data about vaccine exposure (n=3,121,334) and AEIs specified by the EMA (1,488,870 consultations by 430,029 unique individuals). We report relative incidence (RI) of AEIs. An RI <1 signified lower AEI rate compared to TIV. Findings: QIV was associated with a RI of AEIs of 1.14 (95%CI, 1.10-1.18, p<0.01), though the number of years exposure was limited. By way of contrast, LAIV had a lower rate 0.60 (95%CI 0.63-0.68, p<0.001). Cellular manufacture was also associated with a lower rate 0.78 (95%CI 0.61-0.99, p=0.04). AEIs varied by season rash and musculoskeletal conditions are particularly pronounced in the 2014/15 season and respiratory conditions in 2016/17. Interpretation: Routine sentinel network data can be used to contrast AEIs between vaccine types and may provide a consistent method of observation of vaccine benefit-risk over time. The contracting RIs may help guide policy and vaccine choice. Funding: JWC Health Education England academic placement. Declaration of Interest: SdeL received funding from GSK to conduct EMA specification enhanced surveillance of AEIs, through the University of Surrey. He has attended Sanofi, and Seqirus advisory boards. Ethical Approval: The study was approved by RCGP, and the Health Research Authority/ Medical Research Council tool suggested this was a service evaluation of usual practice study not requiring further ethical review.