CPRD StudyPrimary Care PASS Study

Abstract 873: Methodological Approaches to Enhanced Safety Surveillance for Seasonal Flu Vaccines: Early Experience in the UK

Abstract 873: Methodological Approaches to Enhanced Safety Surveillance for Seasonal Flu Vaccines: Early Experience in the UK

Lorna Hazell, Saad AW Shakir, Andrew Finlay, Hannah Coulter, Robert S Brody and Robert P Wise


In 2014, the European Medicines Agency issued draft guidance for enhanced safety surveillance (ESS) on seasonal influenza (flu) vaccines. In the UK, conventional vaccine surveillance is through spontaneous reporting which is limited by under-reporting and lack of denominator data. We have therefore developed and implemented new methods for ESS.


To describe pilot experience of ESS in the UK.


In 2014/5, an ‘active’ surveillance study was conducted on an intranasal flu vaccine used in children (Q-LAIV: quadrivalent live attenuated influenza vaccine). Vaccinees were invited to participate after routine vaccination at participating GP practices and schools. Postal or electronic questionnaires solicited data on adverse events (AE) of interest 14 days after vaccination. Incidence rates were calculated for reported AEs.

In contrast, for 2015/6, a ‘passive’ ESS programme was conducted on the same vaccine. Vaccinees were handed a Safety Report Card (SRC) after vaccination and asked to report any suspected adverse drug reactions (sADRs) directly to the vaccine manufacturer. Reporting rates for sADRs were calculated using concurrent denominator data provided by immunisation sites.

Both pilots were collaborations between DSRU and AstraZeneca, were supported by the UK Clinical Research Network and received Ethics Committee approvals.


In the ‘active’ design, 385 (64%) of 600 recruited vaccinees responded (46 immunisation sites), of which 237 experienced AEs. In the ‘passive’ ESS, 165 vaccinees reported sADRs (1.9% of 8,753 SRCs issued; 67 sites). In both years, the most frequently reported symptoms were pyrexia, malaise, rhinorrhoea, cough and headache. One serious event was reported in the passive phase (flu-like symptoms requiring hospitalisation).


Both active and passive ESS are feasible methods to collect patient-reported safety outcomes that may otherwise go unrecorded. Whilst both methods can capture denominator data, larger samples are needed to detect rare events. Reporting rates in the passive model were low. Promotion of safety surveillance, however, requires caution so as not to affect vaccine uptake.

DSRU, a not-for-profit organisation, and AstraZeneca who provided funding, collaborated on both pilot studies.