Immunogenicity and safety of the first indigenously developed Indian tetravalent influenza vaccine (split virion) in healthy adults ≥ 18 years of age: A randomized, multicenter, phase II / III clinical trial

This phase II / III clinical trial was conducted to evaluate the immunogenicity and safety of the Tetravalent Influenza vaccine (Split virion) I.P. (TetIV) developed indigenously in the country for the first time by M/s Cadila Healthcare Limited, India containing two influenza A and two influenza B strains, one of each, Yamagata (B/Phuket) and Victoria (B/Brisbane) lineage and also compare it to that of an licensed seasonal Trivalent Influenza vaccine (TriIV) of Sanofi Pasteur India Private Limited, containing the two influenza A and only the Yamagata lineage (B/Phuket) strain. Three hundred and fifty subjects of either sex, aged more than 18 years of age, were randomized in a 1:1 ratio to receive either the TetIV or TriIV. Immunogenicity assessments (antibody against A/H1N1, A/H3N2, B/Phuket and B/Brisbane) were done by Haemagglutination Inhibition assay at baseline and 21 d after vaccination. Solicited (local and systemic) and unsolicited adverse events were recorded for up to 42 d following vaccination. The TetIV was found to fulfill the criteria set by the European and the US regulatory authorities and WHO guidance on the requirements of clinical data for licensure of seasonal inactivated influenza vaccines. The seroconversion rates with TetIV were 93.5% for A/H1N1, 90.0% for A/H3N2, 70.0% for B/Phuket and 82.9% for B/Brisbane strain. There was no significant difference in the seroconversion and seroprotection rates at day 21 for A/H1N1, A/H3N2 and B/Phuket in the two groups while the TetIV was superior to the TrivIV for the seroconversion and the seroprotection rate for the B/Brisbane strain (Victoria lineage). Both the vaccines were well tolerated by all the study participants; addition of the fourth strain in the TetIV did not compromise the safety as compared to TriIV. The most common systemic adverse event reported in both the groups was headache followed by fever.