EFFICACY OF LIVE ATTENUATED AND INACTIVATED INFLUENZA VACCINES IN SCHOOLCHILDREN AND THEIR UNVACCINATED CONTACTS IN NOVGOROD, RUSSIA

Children aged 7-14 years in Novgorod, Russia, were given Russian live cold-adapted or inactivated influenza vaccines or placebo over a 2-yea r period. Schools were randomly assigned as a whole to one of the prep arations. In the first year, the vaccines were bivalent, containing ty pes A (H3N2) and A (H1N1) components. In the second year, the vaccines also contained a type B component. In the first year, all viruses iso lated were type A (H3N2); in the second, about three-quarters of the i solates were type B and the rest type A (H1N1). During both years, the vaccines protected the vaccinated children. Where significant differe nces existed, the live attenuated vaccine was more protective than the inactivated. Vaccination rates in schools in which live attenuated va ccines had been used were inversely related to illness rates of staff and unvaccinated children, suggesting that viral transmission had been reduced by the vaccine.