STUDIES ON INFLUENZA IN THE PANDEMIC OF 1957-1958. I. AN EPIDEMIOLOGIC, CLINICAL AND SEROLOGIC INVESTIGATION OF AN INTRAHOSPITAL EPIDEMIC, WITH A NOTE ON VACCINATION EFFICACY*

Abstract

A localized epidemic of influenza A on a hospital ward caused illness in 30 of 62 persons. The disease closely resembled previous descriptions of typical influenza. Three patients with rheumatic heart disease developed serious pulmonary complications. Lymphocytopenia was observed during the first 4 days of illness in many patients. The incidence of serologically confirmed influenza was 34% less in vaccinated than in nonvaccinated subjects. Determination of both hemagglutinating-inhibiting and complement fixing antibodies increased the number of cases diagnosed. The mean magnitude of complement fixing antibody increase was fourfold greater in seriously ill patients than in other patients with significant serologic response to influenza infection.