A clinical trial to assess the immunogenicity and safety of Inactivated Influenza Vaccine (Whole Virion) IP (Pandemic Influenza (H1N1) 2009 Monovalent Vaccine; VaxiFlu-STM) in healthy Indian adult population

Abstract

The pandemic of H1N1 2009 influenza has spread world over and low degree of virus transmission has continued in several regions of India. To assess the immunogenicity and safety of Pandemic Influenza (H1N1) 2009 Monovalent Vaccine in healthy adult Indian population. Prospective, open label, multicentric, phase 2/3 clinical trial. Healthy adult Indian subjects belonging to either 18-59 years or ≥ 60 years age groups were enrolled and administered a single 0.5 ml (≥ 15 mcg of hemagglutinin antigen) dose of vaccine in the deltoid muscle. Anti-hemagglutinin antibody titer was assessed at baseline and 21 (± 2) days after vaccination by Hemagglutination Inhibition (HI) test. Safety assessments were done for a period of 42 days. Percentages of appropriate population with 95% confidence intervals calculated, log transformation of the data to calculate Geometric Mean Titers (GMTs) and chi-square test and student's t-test applied for significance testing. 182/198 and 53/63 volunteers in age groups of 18-59 years and ≥ 60 years, respectively, achieved an HI titer ≥ 1 : 40 at Day 21 (91.9% [95% confidence interval: 88.1-95.7%] and 84.1% [75.1-93.2%]; P=0.072). Further, 171/198 and 50/63 volunteers in the respective age groups achieved seroconversion/four-fold increase in titer at Day 21 (86.4% [81.6-91.1%] and 79.4% [69.4-89.4%]; P=0.179). A significant rise of 22.6-fold [18.0-28.4] and 10.5-fold [7.4-15.0] was noted in GMT in the respective age groups (P<0.001 for both groups as compared to baseline). Nine vaccine-related adverse events were reported (3.4% incidence [1.2-5.6%]), which were of low severity only. Pandemic Influenza (H1N1) 2009 Monovalent Vaccine produces excellent immunogenic response with a good tolerability profile in adult Indian population.