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Update: Influenza Activity -- United States, 1990-91

During December 1990 (weeks 48-52) and January 1991 (weeks 1 and 2), influenza and influenza-like illness activity were higher in the United States than in previous weeks (Table 1). As of January 18, greater than 95% of the approximately 125 influenza virus isolates reported to CDC have been influenza B. Deaths associated with pneumonia and influenza are at levels expected for this time of year.

During December, a small number of outbreaks of influenza-like illnesses were reported in schools and colleges in the northeastern United States. Through January 18, there have been no reports of outbreaks in chronic-care facilities or nursing homes. Reported by: State and territorial health department epidemiologists and state public health laboratory directors. WHO Collaborating Laboratories. Sentinel Physicians Influenza Surveillance System of the American Academy of Family Practice. Epidemiology Office and Influenza Br, Div of Viral and Rickettsial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: During the 1989-90 influenza season, widespread influenza outbreaks occurred during December 1989, and influenza A(H3N2) was the predominant virus isolated. Although influenza B has been the predominant virus isolated this season, culturing for influenza viruses remains important in the evaluation of respiratory illnesses in high-risk persons, especially those in group living situations, because amantadine may be useful in treatment and prophylaxis if influenza A is identified (1). Amantadine is effective against influenza A but not against influenza B. Parents and health-care workers should consult a physician before administering aspirin to children with influenza and influenza-like illness because its use may increase the risk for Reye syndrome (2).


  1. ACIP. Prevention and control of influenza. MMWR 1990;39(no. RR-7).

  2. Hurwitz ES, Barrett MJ, Bregman D, et al. Public Health Service Study of Reye's Syndrome and Medications: report of the main study. JAMA 1987;257:1905-11.

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