Influenza epidemic in Pennsylvania.
D000041:Absenteeism; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D005843:Geography; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D009787:Occupational Medicine; D010414:Pennsylvania; D011014:Pneumonia / Q000401:mortality; D012572:School Health Services; D012737:Sex Factors