Augmented CD4+ T-cell and humoral responses after repeated annual influenza vaccination with the same vaccine component A/H1N1pdm09 over 5 years

The study flow chart. Healthcare workers (HCWs) were vaccinated with a single dose of the AS03-adjuvanted monovalent pandemic H1N1pdm09 vaccine (European Clinical Trials Database, EudraCT 2009-016456-43; www.clinicaltrials.gov, {"type":"clinical-trial","attrs":{"text":"NCT01003288","term_id":"NCT01003288"}}NCT01003288). During 2010–2013 seasons, HCWs were vaccinated every year with the trivalent seasonal inactivated vaccines, containing the H1N1pdm09 virus as the A/H1N1 component during the whole study period. The A/H3N2 and B strains included in the seasonal vaccines changed between seasons during 2010–2013. The figure shows the inclusion criteria for this study, which were repeated annual vaccination between 2010 and 2013, and provision of peripheral blood monocular cells (PBMC) prevaccination (D0) and 21 days postvaccination (D21) in 2012 and 2013 season