Comparison of live attenuated and inactivated influenza vaccines in schoolchildren in Russia: I. Safety and efficacy in two Moscow schools, 1987/88.

The performance of two doses of cold-adapted live attenuated vaccine versus one dose of whole-virus inactivated vaccine was compared in 8-15-year-old schoolchildren in two schools in Moscow, Russia, during the winter of 1987/88. Both vaccines gave rise to low frequencies of associated febrile or systemic reactions, but the inactivated vaccine, delivered by jet injector, did cause small local reactions in about half of the children. Immunogenicity was higher for both vaccines in antibody-free children, and higher levels of serum antibody were detected following use of inactivated vaccine. During the winter, influenza A (H3N2) and influenza B viruses circulated in Moscow. A clear outbreak of (H3N2) virus occurred in both schools, and infections with type B virus also occurred in one school. The influenza A/Philippines/2/82 (H3N2) component of both vaccines exhibited protective efficacy of about 40% (p < 0.05) against serologically proven infection caused by the antigenically drifted A/Sichuan/2/87 (H3N2)-like epidemic viruses in one school. In another school where illnesses associated with antibody rise were documented, efficacy was seen for both vaccines in reduction of illnesses, and of illnesses with serological evidence of infection, but statistical significance was not achieved.