Flu vaccine among worst in decade

Mike Stobbe
Associated Press

New York – — As predicted, 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 last decade, since U.S. health officials started routinely tracking how well vaccines work. In the best flu seasons, the vaccines were 50-60 percent effective.

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 Michigan Department of Community Health’s Bureau of Laboratories reports that 282 positive influenza results have been reported for the 2014-15 season. But that only represents a small portion of the cases statewide, and individual ones are not required to be reported to the state, spokeswoman Jennifer Smith said.

“The flu season can last until May, so it’s too early to say with certainty what kind of year it’s going to be overall, or to know which strains of influenza will circulate later in the season,” Smith said.

“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.

The findings are not surprising. In early December, CDC officials warned the vaccine probably wouldn’t work very well because it isn’t well matched to a strain that’s been spreading widely.

“Vaccination is still recommended because even when protection levels are reduced, the vaccine offers benefits by protecting against additional strains and infections while lessening the risk of related, more serious health complications,” Smith said.

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 are usually 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.

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.

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 may prove to be worse. Hospitalization rates in people 65 and 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 for elderly people.

The CDC began regularly tracking the effectiveness of the flu vaccine during the 2004-05 season, but the results for the first few years were from smaller studies and are considered less reliable. Over the years, effectiveness has ranged from 47 percent to 60 percent in the last half-dozen years, when studies involved larger numbers of patients.

It’s only in those last several years that “we really understand what’s really going on” with the flu vaccines, said Dr. Arnold Monto, a University of Michigan flu expert and another author of the study.

Detroit News Staff Writer

Mark Hicks contributed.