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 21-30 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] 7.3-13.1), 8.9 (95% CI 5.4-14.7), and 12.5 (95% CI8.7-18.2), and significantly increased to 49.8 (95% CI 31.3-79.4, P < 0.001), 43.2 (95% CI 16.3-114.4, P < 0.001), and 323.8 (95% CI 213.9-490.2, P < 0.001), respectively. Deceased-donor type transplant significantly reduced SP (odds ratio [OR] = 4.62, 95% CI 1.36-15.69, P = 0.014) and SC (OR = 6.29, 95% CI 1.89-20.98, P = 0.003) rates, and younger age positively affected SP (OR = 0.11; 95% CI 0.03-0.04, 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.