Flu shots helped protect many Americans against the potentially fatal disease last year even though the vaccine was not well matched against the most common strain that circulated, U.S. officials said Thursday.
A study of 1,359 people in Colorado found that healthy adults between the ages of 50 and 64 were 52 percent less likely to get influenza if they had been vaccinated, the Centers for Disease Control and Prevention reported.
The effectiveness of the jabs dropped to 38 percent for those with one or more chronic medical conditions.
A separate study of Colorado children between the ages of 6 and 23 months showed that those who had never been vaccinated against the flu needed to be given two doses of the vaccine to be protected.
The Atlanta-based federal agency said the findings underscored U.S. government recommendations that call for millions of children and adults to be vaccinated in preparation for the 2004-2005 flu season.
“The bottom line is that the vaccine provides health benefits. It prevents illness even in a year where we don’t have a great match,” said Dr. Carolyn Bridges, a CDC epidemiologist.
Federal officials estimate the disease, which is marked by respiratory inflammation, fever, muscle pain and intestinal tract irritation, typically kills about 36,000 people and hospitalizes 114,000 in the United States every year.
The 2003-2004 flu season was one of the most severe in the United States in recent memory. Exact figures for adult fatalities are not available, but the disease killed more than 150 adolescents and children.
Officials contend that getting a flu shot can cut the risk of getting the disease by up to 90 percent when there is a good match between the vaccine and the strains that are circulating.
But the vaccine that was taken by tens of millions of Americans last year contained a strain that was similar but not identical to the virulent A (H3N2) Fujian flu strain that ended up predominating in the nation.
The CDC estimates that about 100 million doses of vaccine will be available for the 2004-2005 flu season.