COMPARATIVE-STUDIES OF LIVE AND INACTIVAT ED INFLUENZA VACCINES - ORGANIZATION OF THE OBSERVATIONS AND THE RESULTS OF STUDIES ON REACTOGENICITY AND IMMUNOGENICITY

Schoolchildren of 30 to 34 schools of Novgorod were vaccinated over a three-year period with Russian live cold-adapted attenuated vaccine fo r children and whole-virus inactivated vaccines and placebo for compar ative field study of the vaccines properties and efficacy. In control trials both bi-and trivalent live attenuated vaccines were well tolera ted and areactogenic. A whole-virus inactivated trivalent vaccine indu ced mild and moderate fever and local reactions in 2-4 % of the vaccin ees. Special observations are necessary to establish the possibility o f use and to determine a dose of this inactivated vaccine for immuniza tion of children, especially those of 7-10 years of age. All the vacci nes induced HI antibody production in 50-80 % and antineuraminidase in 50-70 % of seronegative children. The pattern of the results was simi lar to that in revaccinated children with preexisting antibody at a le vel of 1:20, but much lower in children with the initial titre above 1 :20. After the 3rd year of vaccination the immune response of the vacc inees was similar, most of the results depending on the initial antibo dy titre and also on the change of vaccine strains. This raises a ques tion of the expediency of annual influenza revaccination of the same p erson after 2 years of successful immunization and of the necessity of vaccine strains replacement after 2-3 years of use.