Efficacy of Purified Influenza Subunit Vaccines and Relation to the Major Antigenic Determinants on the Hemagglutinin Molecule

This is the authors' abstract. We don't add key points for this paper.

Inactivated whole-virus vaccine of influenza A/Scotland/74 (H3N2) virus containing 700 or 1,400 chick cell-agglutinating (CCA) units, a purified subunit vaccine of equivalent dosage, or placebo were studied in 186 adult volunteers. Placebo was least reactogenic, 1,400-CCA unit whole-virus vaccine was most reactogenic, and others were intermediate. Vaccines were equally antigenic, and delineation of antibody specificities revealed antibody cross-reacting with A/Hong Kong/68 (H3N2) virus in all sera. Antibody specific for A/Hong Kong/68 virus was found in 82% of sera and for A/Scotland/74 virus in 46%. When compared with volunteers given placebo, volunteers given 700 CCA units of subunit or whole-virus vaccine exhibited significant protection against infection with live A/Scotland/74 virus. Infections in vaccinees occurred only in those with low titers of antibody to A/Scotland/74 virus, and this antibody was of the cross-reacting type. Persons with moderate and high levels of antibody resisted infection regardless of the absence or presence of antibody specific for A/Scotland/74 virus. Purified subunit vaccines provide an alternative to whole-virus preparations in primed individuals. Efficacy of vaccines may be dependent on the nature of the antibody response.