Influenza--United States, 1988-89.
OBJECTIVE
CDC monitors the emergence and spread of new influenza virus variants and the impact of influenza on morbidity and mortality annually from October through May.


METHODS
This report covers United States influenza surveillance conducted from October 1988 through May 1989.


METHODS
Weekly reports from the vital statistics offices of 121 cities provided an index of influenza's impact on mortality; 58 WHO collaborating laboratories reported weekly identification of influenza viruses; weekly morbidity reports were received both from the state and territorial epidemiologists and from 153 sentinel family practice physicians. Nonsystematic reports of outbreaks and unusual illnesses were received throughout the year.


RESULTS
During the 1988-89 influenza season, influenza A (H1N1) and B viruses were identified in the United States with essentially equal frequency overall, although both regional and temporal patterns of predominance shifted over the course of the season. Throughout the season increases in the indices of influenza morbidity in regions where influenza B predominated. Only 7% of identified viruses were influenza A (H3N2), but not isolations of this subtype increased as the season waned and it subsequently predominated during the 1989-90 season. During the 1988-89 season outbreaks in nursing homes were reported in association with influenza B and A (H3N2), but not influenza A (H1N1).


CONCLUSIONS
The alternating temporal and geographic predominance of influenza strains A (H1N1) and B during the 1988-89 season emphasizes the importance of continual attention to regional viral strain surveillance, since amantadine is effective only for treatment and prophylaxis of influenza A.


CONCLUSIONS
Weekly interim analyses of surveillance data produced throughout the season allow physicians and public health officials to make informed choices regarding appropriate use of amantadine. CDC's annual surveillance allows the observed viral variants to be assessed as candidates for inclusion as components in vaccines used in subsequent influenza seasons.
Chapman
L E
LE
Connaught Laboratories, Pasteur-Mirieux Company, Swiftwater, Pennsylvania.
Tipple
M A
MA
Folger
S G
SG
Harmon
M
M
Kendal
A P
AP
Cox
N J
NJ
Schonberger
L B
LB
D004196:Disease Outbreaks; D006801:Humans; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification; D009981:Influenza B virus / Q000276:immunology / Q000302:isolation & purification; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D011159:Population Surveillance; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014944:World Health Organization
D007252:Influenza Vaccines