CDC: Flu shots not that useful for limiting SARS alarms

Oct 2, 2003 (CIDRAP News) – While the Centers for Disease Control and Prevention (CDC) supports widespread influenza vaccination, the CDC doesn't think that measure will be very helpful for limiting unnecessary worries about SARS (severe acute respiratory syndrome).

"CDC does not recommend influenza vaccination for the primary purpose of reducing the number of persons who might be evaluated for severe acute respiratory syndrome," the agency states in the Oct 3 issue of Morbidity and Mortality Weekly Report.

The CDC apparently differs with the World Health Organization (WHO) on that score. A month ago, the WHO said influenza vaccination can "reduce cases of respiratory disease that could be mistaken for SARS or raise suspicions requiring costly investigations." The organization said that because of SARS-related concerns, health authorities in some countries are stepping up their efforts to vaccinate high-risk groups against influenza.

The CDC report says flu vaccination campaigns may reduce the number of people with febrile respiratory illnesses who are evaluated for SARS, but "such secondary benefits cannot reliably be anticipated."

The decrease in febrile respiratory illnesses would be low if flu viruses were not very prevalent or if other respiratory pathogens were circulating, the CDC said. In addition, people who have received a flu shot can still contract flu-like illnesses, because the vaccine is not 100% effective and does not prevent infection by other agents.

"Therefore, receipt of influenza vaccination in a person who subsequently experiences a febrile respiratory illness does not eliminate influenza as a possible cause nor necessarily increase the likelihood that the illness is SARS," the report states.

CDC. Note to readers: SARS, influenza, and use of influenza vaccine. MMWR 2003;52(39):941-2
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5239a5.htm