An investigation of the utilisation and safety of influenza A(H1N1)pdm 2009 vaccines using the UK GPRD

Abstract

Background: Following the outbreak of the Influenza A(H1N1) pandemic, mass vaccination was recommended in the UK, Europe and many other countries throughout the world. Given the limited pre-marketing experience with these vaccines, national and international post-marketing surveillance was recommended.Aim: To contribute to the post-marketing surveillance of the influenza A(H1N1) pdm09 vaccine using the GPRD, to assess the performance of the GPRD as a vaccine surveillance tool and to assess the potential of the VAESCO collaborative working model.Methods: Several studies were carried out, both independently using UK GPRD data and in collaboration with VAESCO partners elsewhere in Europe. Cohort, case-control and self-controlled case series methodologies were used to estimate influenza A(H1N1) pdm09 vaccine uptake in high risk groups, provide background rates of events commonly reported following vaccination for use in passive surveillance and evaluate the risk of Guillain-Barré syndrome and foetal death following influenza A(H1N1) pdm09 vaccination.Results: Uptake of influenza A(H1N1) pdm09 vaccine in clinical risk groups (40.3%) and pregnant women (21.6%) was low. Background rates of facial nerve palsy varied by data source, age, calendar year and calendar month. The risk of Guillain-Barré syndrome was not significantly higher among vaccinated than unvaccinated individuals in the case control (ORadj 1.0, CI95 0.3 to 2.7) or self-controlled case series (IRRadj 1.3 CI95 0.6 to 2.7) studies while the risk of first (HRunadj 0.74, CI95 0.62 to 0.88), second (HRunadj 0.59, CI95 0.45 to 0.77) and third (HRunadj 0.70, CI95 0.47 to 1.03) trimester foetal death was not higher in vaccinated than unvaccinated individuals. Conclusion: The GPRD performed well as a vaccine surveillance tool, providing accurate data on influenza A(H1N1) pdm09 vaccination and disease incidence. While the VAESCO studies produced useful data in a number of European data sources, limitations encountered suggest modification of the working model would be needed for future collaboration.

Date of Award	20 Nov 2013
Original language	English
Awarding Institution	University of Bath
Supervisor	Corinne De Vries (Supervisor) & Anita McGrogan (Supervisor)