Rates of pneumonia during influenza epidemics in Seattle, 1964 to 1975.
Influenza A epidemics were associated with a doubling to tripling of pneumonia rates among adult members of a prepaid medical care group studied between 1963 and 1975. Rates of influenza A associated with pneumonia increased with age. Influenza B epidemics did not have a similar effect. Overall pneumonia rates were highest in children younger than 5 years, but in this age group, other respiratory viruses dominated as causative agents. Influenza A and B epidemics were not always synchronized with those reported for the United States, and rates of influenza A infection varied between urban and suburban areas in sequential epidemics. In 1974, a year practically free from influenza A, a prolonged Mycoplasma pneumoniae epidemic kept rates of pneumonia high, especially during the summer.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology*; D008875:Middle Aged; D009175:Mycoplasma Infections / Q000453:epidemiology; D011014:Pneumonia / Q000453:epidemiology* / Q000401:mortality; D012621:Seasons; D014861:Washington