Safety and immunogenicity of an AS03-adjuvanted A(H1N1)pmd09 vaccine administered simultaneously or sequentially with a seasonal trivalent vaccine in adults 61 years or older: Data from two multicentre randomised trials

► The AS03-adjuvanted A(H1N1)pmd09 vaccine is immunogenic in people aged ≥61 years. ► Co-administration of seasonal influenza and pandemic vaccines is immunogenic. ► Sequential administration of seasonal influenza and pandemic vaccines is immunogenic. ► Both vaccines are well-tolerated following co- or sequential administration.