Enhanced Safety Surveillance of Seasonal Quadrivalent Influenza Vaccines in English Primary Care: Interim Analysis.

INTRODUCTION: The European Medicines Agency (EMA) requires vaccine manufacturers to conduct enhanced safety surveillance (ESS) of seasonal influenza vaccines including a near real-time evaluation of collected data. The objective was to identify whether the use of passive surveillance or active surveillance provides different results of reported adverse events of interest (AEIs) by specified age strata and AEI type. We report the weekly incidence rates of AEIs within 7 days following seasonal influenza vaccination using passive and active surveillance.

METHODS: AEIs were collected within 7 days of vaccination from ten general practices predominantly administering inactivated quadrivalent influenza vaccine (IIV4, Fluarix Tetra, GSK). Vaccinees completed an adverse drug reaction (ADR) card. ADR card and medically attended AEIs data were recorded in practice electronic health records. We report the outcome of the first 5 weeks of safety surveillance (September 12, 2016-October 16, 2016); in an exploratory analysis, rates of AEI for IIV4 are compared to those passively reported through a sentinel network.

RESULTS: Practices vaccinated 13.1% (12,864/98,091) of their registered population; 5.6% (95% CI 5.20-6.00) of them reported AEIs, none serious. The most frequent were respiratory 2.60% (95% CI 2.33-2.88), musculoskeletal 1.82% (95% CI 1.59-2.05) and neurological 1.05% (95% CI 0.88-1.23). AEIs were more frequently reported for adults than for children; 5.91% (95% CI 5.49-6.34) compared to 1.49% (95% CI 0.69-2.29); 47.18% of the adults reported AEI using the ADR card, none were returned for subjects < 18 years old. The frequency of AEIs reporting was higher, 6.88% (95% CI 6.35-7.42) vs. 3.30% (95% CI 2.68-3.96, 100/3028, p < 0.000), through ESS than passive surveillance.

CONCLUSION: The ESS did not reveal any safety signal and we demonstrated the feasibility of conducting ESS following EMA recommendations. The use of a customised ADR card led to a doubling of AEIs reports over passive surveillance in adults.

FUNDING: GlaxoSmithKline Biologicals SA, Wavre, Belgium.