INFLUENZA A AND B VIRUS INFECTION IN INFANTS AND YOUNG CHILDREN DURING THE YEARS 1957–19761

Abstract

Influenza A virus activity was demonstrated in infants and young children from metropolitan Washington, DC during each of 19 successive August—July respiratory disease years, and during 17 of these years at least 2% of hospitalized respiratory disease patients yielded an Influenza A or B virus and/or showed an Influenza A or B serum complement-fixing (CF) antibody response. Between October 1957 and July 1976, 14.3% of 860 croup patients and 5.3% of a total of 5655 hospitalized respiratory patients, including croup patients, showed evidence of influenza A or B virus Infection. The mean period of hospitalization with either virus was about 8 days, though serious Infection with influenza A virus was 4.5 times more common than with Influenza B virus. Both influenza viruses were detected more frequently in respiratory disease outpatients than In respiratory disease inpatients. Patients with serious influenza A virus infections were especially likely to have croup (particularly during the H₃N₂ era), to be seen during December through February, and to be black male infants. During the peak month of a composite of 13 consecutive Influenza A virus outbreaks, Influenza A virus infection was demonstrated In 67.6% of croup patients and in 35.6% of all hospitalized respiratory patients including croup patients. During the peak month of a composite of 6 consecutive Influenza B virus outbreaks, Influenza B virus infection was demonstrated in 36.0% of croup patients and In 10.8% of all hospitalized respiratory disease patients Including croup patients.