Skip Navigation LinksSkip Navigation Links
Centers for Disease Control and Prevention
Safer Healthier People
Blue White
Blue White
bottom curve
CDC Home Search Health Topics A-Z spacer spacer
Blue curve MMWR spacer

Update: Influenza Activity -- United States

Influenza isolates reported to CDC this season have increased from a cumulative total of 276 last month (1) to 707 (Figure 1). Most virus isolates (93%) have been identified as type A(H3N2) related to the A/Bangkok/79 component of the current vaccine, and 5% have been identified as type A(H1N1) related to the A/Brazil/78 component.

Influenza virus isolates have now been reported from 41 states. Forty states have reported influenza type A(H3N2) virus, and 15, including Kentucky, which recently reported its first influenza isolate for this season, have reported type A(H1N1) virus. Six states have reported influenza type B virus (10 isolates).

For the week ending March 4, five states (Iowa, Kentucky, Nebraska, Ohio, and Virginia) reported widespread influenza activity, and 11 states reported regional influenza activity. For the same week, an excess in the ratio of pneumonia and influenza (P&I) deaths to total deaths was reported from 121 cities for the 8th consecutive week (Figure 1). The ratio was 5.1, and the expected ratio was 4.2. During the last season the P&I ratio was significantly elevated--1980/81--the observed ratio rose more abruptly and peaked near 7.0. Reported by Respective state epidemiologists and laboratory directors; Div of Surveillance and Epidemiologic Studies, Epidemiology Program Office, WHO Collaborating Center for Influenza, Influenza Br, Div of Viral Diseases, Center for Infectious Diseases, CDC.


  1. CDC. Update: influenza activity--United States. MMWR 1983;32:75-6.

Disclaimer   All MMWR HTML documents published before January 1993 are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to

Page converted: 08/05/98


Safer, Healthier People

Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention
1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A


Department of Health
and Human Services

This page last reviewed 5/2/01