Swine influenza A at Fort Dix, New Jersey (January-February 1976). II. Transmission and morbidity in units with cases.

Epidemiologic study of 13 influenza A/New Jersey/76 (Hsw1N1) patients indicated that person-to-person transmission had occurred in several distinct military units. Soldiers in eight of these units (companies) were studied to determine whether they had experienced influenza A/New Jersey infections and associated acute respiratory disease. Titers of hemagglutination-inhibiting antibody to influenza A/Mayo Clinic/103/74 (Hsw1n1) antigen were determined. In seven of these eight companies, individuals with titers of greater than or equal to 1:20 were found. In these seven companies, members of platoons with cases (contact platoons) had antibody prevalences of 7%-56%, and members of platoons without cases had prevalences of 0-40%. Hospital admissions for acute respiratory disease were proportionately greater in trainees with A/Mayo Clinic antibody titers of greater than or equal to 1:20 than in trainees without antibody in five of six contact platoons studied.