Last year's flu vaccine, wiped out in a national rush for protection, was partially effective even though it didn't match the type of influenza that circulated most widely, health officials said Thursday.
The flu shots reduced the risk of getting flu by about half, the Centers for Disease Control and Prevention said. Most years, when the vaccine covers the flu strains present, the shots prevent the illness about 80 percent of the time.
"We should continue to vaccinate even when we may not have a perfect match," concluded Dr. Carolyn Bridges, a medical epidemiologist with the CDC's National Immunization Program.
The 83 million doses of last year's vaccine were mostly used up by Christmas after the flu struck early and hard, drawing special attention to deaths and complications among children. As demand grew, Georgia and other states scrambled to get more vaccine. The CDC bought leftover supply and parceled doses to states most in need.
At least 152 children died from lab-confirmed flu throughout the season. Health officials can't say if that is unusual because detailed records are not traditionally kept.
With this year's flu season approaching --- many health departments offer shots in October --- the government says 100 million doses of vaccine will be available, with 4.5 million more in reserve.
No new viral strains have emerged to make this year's vaccine out of date, as was the case last year when the dominant Fujian strain appeared too late to be included in the vaccine.
"It looks like the strains selected for the vaccine will be good for the upcoming year," said Dr. Keiji Fukuda, the CDC's chief of influenza epidemiology. But he cautioned that new strains could arise anytime.
Even with last year's mismatch, the shots protected against lab-confirmed flu in 52 percent of people ages 50 to 64 studied in Colorado, the CDC said. The shots were 49 percent effective in children under age 2 in warding off pneumonia and influenza, though that category may include illnesses other than true flu.
Vaccines engineered to fight certain viral strains can sometimes trigger immune responses to slightly different strains, Bridges said.
Copyright 2004 The Atlanta Journal-Constitution