Abstract IntroductionThe European Medicines Agency (EMA) has released guidance for the surveillance of adverse events of interest (AEIs) following vaccination, early in the influenza season. It is feasible to capture brand-specific AEIs using a sentinel practice network, such as the Royal College of General Practitioners Research and Surveillance Centre (RCGP RSC).MethodUsing the RCGP RSC dataset, we identified brands for 344,542 patients receiving the seasonal influenza from 01/09/2016 to 04/12/2016. We identified any relevant AEIs, as specified by EMA, up to 7 days post-vaccination. We produced overall rates for each brand.Results76.3% of vaccinated patients had an identified brand; out of these, 3.7% had an AEI. Brand A had a share of 9.6% (95%CI 9.5-9.7) of the vaccines, and 7.4% (95%CI 6.9-7.9) of the AEIs. Brand B had 29.1% (95%CI 28.9-29.3) of the vaccines, and 28.8% (95%CI 27.9-29.7) of the AEIs. Brand C had 44.9% (95%CI 44.7-45.0) of the vaccines, and 41.0% (95%CI 40.0-42.0) of the AEIs. Brand D had 9.3% (95%CI 9.1-9.4) of the vaccines, and 10.1% (95%CI 9.5-10.7) of the AEIs. Brand E had 7.2% (95%CI 7.1-7.2) of the vaccines, and 12.7% (95%CI 12.1-13.4) of the AEIs.ConclusionBrand A and C had a significantly lower proportion of AEIs compared to their share of vaccines, while the opposite was true for Brand D and E. Further work will explore the feasibility of using the self-controlled case series method to quantify the level of brand-specific risk of AEIs. External funding details The RCGP RSC work is primarily funded by PHE.