NEW YORK — This year’s flu vaccine is doing a pretty crummy job. It’s only 23 percent effective, primarily because it doesn’t include the bug that is making most people sick, according to a government study released Thursday.
That’s one of the worst performances in the past decade, since U.S. health officials started tracking how well vaccines work. In the best flu seasons, the vaccines were 50 percent to 60 percent effective.
This is an uncommon year,” said Dr. Alicia Fry, a flu vaccine expert at the Atlanta-based Centers for Disease Control and Prevention, who was involved in the study.
Each year, the flu vaccine is reformulated, based on experts’ best guess at 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 enough doses.
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 this a particularly bad winter to have a problem with the flu vaccine.
