Flu shot seen as just 23% effective
NEW YORK — This year’s flu vaccine is doing a pretty crummy job. It’s only 23 percent effective, which is one of the worst performances in the past decade, according to a government study released yesterday.
The poor showing is primarily because the vaccine doesn’t include the bug that is making most people sick, health officials say. In the past decade, flu vaccines at their best were 50 to 60 percent effective. “This is an uncommon year,” said Dr. Alicia Fry, a flu-vaccine expert at the Centers for Disease Control and Prevention who was involved in the study.
The findings are not surprising, though. In early December, CDC officials in Atlanta warned that the vaccine probably wouldn’t work very well because it isn’t well-matched to a strain that’s been spreading widely.
Each year, the flu vaccine is reformulated based on experts’ best guess about which three or four strains will be the biggest problem. Those decisions usually are made in February, months before the flu season, to give companies that make flu shots and nasal-spray vaccine enough time to make doses.
But this year’s formula didn’t include the strain of H3N2 virus that ended up causing about two-thirds of the illnesses this winter. And that strain tends to cause more hospitalizations and deaths, particularly in the elderly, making it a particularly bad winter to have a problem with the flu vaccine.
Indeed, the flu season is shaping up to a bad one. Health officials are comparing it to the nasty flu season two winters ago, and this one might prove to be worse. Hospitalization rates in people 65 or older are higher than they were at the same point in the 2012-13 season, according to CDC data. The results from the preliminary study weren’t large enough to show how the vaccine is working in each age group, although flu vaccines traditionally don’t work as well in elderly people.
The study involved 2,321 people in five states — Michigan, Pennsylvania, Texas, Wisconsin and Washington — who had respiratory illnesses from November to early January. The researchers said vaccinated people had a 23 percent lower chance of winding up at the doctor with the flu. CDC officials say people still should get a flu shot this year. Recently, the flu season in the United States has peaked in January or February, but people can continue to get sick for months. And they could get infected by the flu strains that were included in this year’s version.