[Safety and immunogenicity on three lots of influenza split vaccines among adults]

To evaluate the immunogenicity, safety and stability of the manufacture process regarding three consecutive lots of influenza split vaccines (Anflu).

A double-blind, randomized and controlled clinical trial was conducted in healthy volunteers. A total of 566 subjects aged 18 to 60 years were recruited and stratified into four age groups before randomly assigned into four groups. Each group would receive one dose of influenza vaccine from either one of the three lots of Anflu or one lot of the licensed control vaccine. Each dose of the vaccines contained 15 microg of each of the H1N1, H3N2 and B type antigen. Safety was assessed through 30-minute observation for immediate allergic reaction and three-day observation after vaccination. HI antibody titers were determined before vaccination and on day 21, after vaccination.

Mild adverse reaction was reported and the overall incidence rates on fever of the four groups were from 1.4% to 2.8% but no significant difference was observed between groups. Seroconversion rates of the three viral strains in four groups were 80.3% and above with fold increase as > or = 11.1 and protection rate was > or = 93.4%. For the three lots of investigated vaccines, all of the indexes of the three viral strains in four groups exceeded the standards on EMEA and FDA for influenza vaccine.

The three consecutive lots of Anflu appeared to be good, with both consistent immunogenicity and safety, indicating the stability of manufacture process.