Nonetheless, the Centers for Disease Control and Prevention says people should still get a flu vaccine, because it does work well against strains of flu that may not be circulating just now, but that may show up at any time.
“Right now, the effectiveness is not as good as we normally see with influenza. We want people to know that so they know to call their doctor for antivirals if they are sick,” says CDC’s Dr. Joe Bresee.
The CDC had been warning the vaccine might not work well this year. Just after drug makers started cooking up batches of flu vaccine for the 2014-2015 season, a sneaky strain of H3N2 started circulating that’s different from the strain the vaccine protects against. Flu vaccines take months to make and it was too late to change the formula for this year.
So the CDC’s been reminding people that there are three antiviral drugs on the market that can help you recover more quickly from flu. Tamiflu is the pill most widely prescribed, and there are injectable and inhalable drugs, too.
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Unlike with antibiotics, there is not a big downside to taking a flu drug without being sure you have influenza.
And it’s even OK to just call your symptoms in to your doctor so you can fill the prescription right away – because time is of the essence in treating flu.
“We think so, especially when flu is peaking in a community, the chance that a person who calls in and says I have flulike symptoms actually has flu is probably high – well over 50 percent. You will treat some people unnecessarily but you’ll get a lot right,” Bresee said.
Dr. Arnold Monto of the University of Michigan helped gather the data on whether the vaccine works well. The report’s been thrown together quickly because the flu season started unusually early this year, so 23 percent is by no means a final efficacy number. “These interim estimates are always a little uncertain,” Monto said.
The findings give a good picture of how well the vaccine prevents severe disease – infections bad enough to send people to the doctor’s office. It doesn’t show whether the vaccine may be protecting people against milder illness. And it actually does not show precisely whether the vaccine is preventing flu completely in people.
“What we are doing here is looking at those who been seen in medical care and who have a flu-like illness and comparing those who turn out to be (positive for flu), looking at their vaccination rates,” Monto said.
So among about 2,300 people who went to their doctors for flu, 41 percent of them actually did have influenza and the rest had something else. Just about half the people who truly had flu had been vaccinated this year, compared to 56 percent of the people who didn’t have flu. That works out to a 23 percent protection rate.
What the study doesn’t show is whether the vaccine is somehow making illness less severe – people may still get sick but they aren’t sick enough to go to the doctor. “The studies that we do can’t get at that question very well,” Bresee said.
So CDC says even if the vaccine doesn’t do a perfect job this year, it’s still important to get vaccinated. Often, a second strain such as influenza B can start circulating late in the season and the vaccine protects against either one or two of the most common B strains.
“And still, 30 percent of the virus that we are seeing is well matched to the vaccine,” Bresee said.
“People should realize that the vaccine does have protective efficacy,” Monto told NBC News. “They should get the vaccine. But we need to keep working on improved influenza vaccines.” Companies and the federal government are working on that.
Even when the vaccine is only 10 percent effective, that translates into 13,000 elderly people who don’t end up in the hospital with flu, CDC says.