Introduction The European Medicines Agency requires Marketing Authorisation Holders providing seasonal influenza vaccines in Europe to conduct enhanced safety surveillance accounting for the different age groups based on the vaccine indication, in order to detect any potential increase of local and systemic adverse reactions early in an influenza season. To comply with this requirement, a multicountry European passive enhanced safety surveillance study has been set up to capture and assess adverse events occurring within 7 days following seasonal influenza vaccination. Here we share our surveillance protocol for the 2018/2019 influenza season. Methods Nine healthcare professionals (HCPs) in Belgium, Germany and Spain have been recruited for this study. Cumulatively, approximately 1000 vaccinees will be provided with customised adverse event recording cards to report adverse events experienced within 7 days following vaccination with GSK’s split-virion inactivated quadrivalent influenza vaccine. The cards are to be returned to the HCPs and the events encoded using an electronic case report form. Adverse event reporting rates will be analysed weekly and cumulatively, throughout the study period. Event rates will be described by country, age group and by influenza morbidity/mortality risk status of vaccinees (based on HCP assessment). Ethics and dissemination Ethics committee approval was obtained for all participating sites prior to enrolment of the study participants. At the end of the study, each participating site will receive their data, and the outputs from the research will be made available to regulatory authorities. We intend to seek publication in peer-reviewed journals. GSK has posted a summary of the study protocol before the start of the study and results will be posted within 12 months of statistical analysis completion, in line with the National Institutes of Health recommendations. Trial registration number NCT03688620 .