CDC: Mismatched flu vaccine still effective

Study shows ’03 vaccine prevented illness

Although last year’s influenza vaccine was not a good match with the circulating viruses, the vaccine still was somewhat effective, according to new studies reported by the Centers for Disease Control and Prevention (CDC).

A well-matched vaccine usually is 70% to 90% effective in preventing illness. The 2003-04 vaccine was 38% to 52% effective in preventing illness, according to a report in the Aug. 13 Morbidity and Mortality Weekly Report.

A previous study of the vaccine in health care workers did not show effectiveness against influenzalike illness. The focus on laboratory-confirmed influenza in the more recent study among patients ages 50 to 64 was able to demonstrate a clearer benefit, the study authors said.

CDC expects 90 million to 100 million doses of vaccine to be available this year, an increase over last year, when a strong demand led to shortages in some areas. The vaccine will contain A(H3N2), A(H1N1), and B viruses.