Antibody response to the non-adjuvanted and adjuvanted influenza A H1N1/09 monovalent vaccines in renal transplant recipients

Background The 2009 pandemic influenza A (H1N1) virus spread rapidly throughout Brazil. Non-adjuvanted and the adjuvanted influenza A H1N1/09 monovalent vaccine were recommended as a single dose to persons at risk including renal transplant recipients (RTR). We analyzed the safety and the immune response of 2 influenza A H1N1/09 monovalent vaccines in RTR, and identified factors influencing the immune response. Methods A total of 78 RTR received a single dose of either influenza A H1N1 2009 monovalent AS03-adjuvanted vaccine or a non-adjuvanted vaccine, and 58 healthy controls received a single dose of non-adjuvanted vaccine. Antibody responses to influenza A H1N1 were measured by hemagglutination inhibition assay and were compared between groups on the day of vaccination and 2130 days thereafter, using geometric mean titer (GMT), and seroprotection (SP) and seroconversion (SC) rates. Results Among RTR, after adjuvanted and non-adjuvanted H1N1 vaccination, the SP rate increased from 16.7% to 61.7% (P < 0.001) and to 50% (P < 0.001), and SC rates were 61.7% and 50%, respectively. For healthy controls, SP rate increased from 25.8% to 89.7% (P < 0.001), and SC rate was 87.9% after vaccination. Pre-vaccination GMT for the adjuvanted and non-adjuvanted RTR vaccine groups and healthy controls was 9.7 (95% confidence interval [CI] 7.313.1), 8.9 (95% CI 5.414.7), and 12.5 (95% CI8.718.2), and significantly increased to 49.8 (95% CI 31.379.4, P < 0.001), 43.2 (95% CI 16.3114.4, P < 0.001), and 323.8 (95% CI 213.9490.2, P < 0.001), respectively. Deceased-donor type transplant significantly reduced SP (odds ratio [OR] = 4.62, 95% CI 1.3615.69, P = 0.014) and SC (OR = 6.29, 95% CI 1.8920.98, P = 0.003) rates, and younger age positively affected SP (OR = 0.11; 95% CI 0.030.04, P = 0.001). Adverse events were mild, and renal function showed no change post vaccination. Conclusion RTR vaccinated with either an adjuvanted or non-adjuvanted monovalent influenza vaccine presented poor response compared with healthy controls. Post-vaccination adverse events were mild, and no rejection episode or renal dysfunction was observed.