ATLANTA — The flu season is getting worse, and U.S. health officials say it's partly because the flu vaccine doesn't protect against most of the spreading flu bugs.
The flu shot is a good match for only about 40 percent of this year's flu viruses, officials at the U.S. Centers for Disease Control and Prevention said Friday.
That's worse than last week's report when the CDC said the vaccine was protective against roughly half the circulating strains. In good years, the vaccine can fend off 70 to 90 percent.
Infections from an unexpected strain have been booming, and now are the main agent behind most of the nation's lab-confirmed flu cases, said Dr. Joe Bresee, the CDC's chief of influenza epidemiology.
It's too soon to know whether this will prove to be a bad flu season overall, but it's fair to say a lot of people are suffering at the moment. "Every area of the country is experiencing lots of flu right now," Bresee said.
This week, 44 states reported widespread flu activity, up from 31 last week. The number of children who have died from the flu has risen to 10 since the flu season's official Sept. 30 start.
Those numbers aren't considered alarming. Early February is the time of year when flu cases tend to peak. The 10 pediatric deaths, though tragic, are about the same number as was reported at this time in the last two flu seasons, Bresee said.
The biggest surprise has been how poorly the vaccine has performed.
A bad match
Each winter, experts try to predict which strains of flu will circulate so they can develop an appropriate vaccine for the following season. They choose three strains — two from the Type A family of influenza, and one from Type B.
Test your IQUsually, the guesswork is pretty good: The vaccines have been a good match in 16 of the last 19 flu seasons, experts said.
But the vaccine's Type B component turned out not to be a good match for the B virus that has been most common this winter. And one of the Type A components turned out to be poorly suited for the Type A H3N2/Brisbane-like strain that now accounts for the largest portion of lab-confirmed cases.
Don't miss these Health stories
More women opting for preventive mastectomy - but should they be?
Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.
- Larry Page's damaged vocal cords: Treatment comes with trade-offs
- Report questioning salt guidelines riles heart experts
- CDC: 2012 was deadliest year for West Nile in US
- What stresses moms most? Themselves, survey says
- More women opting for preventive mastectomy - but should they be?
“Typically, they’re very successful at that, but this is just one of those years where it was a little off, and it hasn’t been as good of a match," John Silcox of the Fort Wayne-Allen County, Ind., Department of Health told WISE-TV in Fort Wayne.
"So that’s why we’re perhaps seeing a little bit more flu.”
Over the years, the H3N2 flu has tended to cause more deaths, Bresee said.
That may be little comfort for the suffering masses. In Philadelphia, Health Commissioner Donald F. Schwarz cited what he called an unusually sharp increase in the number of people with the flu. Emergency room doctors said they were seeing more cases and worse symptoms than last year.
“This year’s been more virulent. People last year had a mild case of the flu and stayed home. This year, they feel a lot more miserable, and we’re treating accordingly," Dr. Ben Usatch of Lankenau Hospital told WCAU-TV in Philadelphia.
The flu appears to be taking a heavy toll on college students. At the University of Kentucky, in Lexington, doctors have been seeing 20 to 30 students a day with flu symptoms, said Gregory Moore, director of University Health Services. He said conditions on campuses were usually prime for the flu to attack.
“People are living in close proximity,” Moore told WLEX-TV in Lexington. “Unfortunately, some of our students aren’t eating well or sleeping well.”
“I woke up with a fever, started around 101, went up to 103 by the time it was over,” said Elizabeth Shemwell, a student at the university. “Body aches, fever chills, headache, everything. The works — I had it.”
This week, the World Health Organization took the unusual step of recommending that next season's flu vaccine have a completely different makeup from this year's. The U.S. Food and Drug Administration is expected to make its decision about the U.S. vaccine next week.
H3N2 strains are treatable by Tamiflu and other antiviral drugs, but the other, H1N1 Type A strains are more resistant. Of all flu samples tested this year, 4.6 percent have been resistant to antiviral medications. That's up from less than 1 percent last year.
"This represents a real increase in resistance," Bresee said.
Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.