The antibody response to pandemic H1N1 2009 influenza vaccine in adult organ transplant patients

Summary Limited data are available regarding antibody response and the safety of the monovalent influenza A H1N1/09 vaccine for immunocompromised patients. In this study, the humoral response to this vaccine in solid organ transplant (SOT) recipients and healthy individuals was evaluated. Eighty-two SOT recipients and 28 healthy individuals received two doses of the influenza A H1N1/09 AS03 adjuvanted vaccine containing 3.75 mg of haemagglutinin at a 3- to 4week interval. Serum samples were drawn at baseline and 3‐4 weeks after the first and second vaccine doses. Seroprotective titres were measured with a haemagglutination inhibition. After the first dose seroprotective titres were observed in 69% of the SOT patients and in 96% of the healthy controls (P = 0.006), and increased after the second dose to 80% and 100%, respectively (P = 0.003). All controls and 77% of the SOT recipients achieved a ‡4-fold titre rise after the first immunisation (P = 0.005). The vaccine was well tolerated and no acute rejection was observed. Influenza A H1N1/09 vaccine elicited a protective antibody response in the majority of SOT recipients, but the response was lower when compared with controls. A second dose significantly improved vaccine immunogenicity in SOT recipients. (ClinicalTrials.gov number: NCT01254955)