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CDC: Flu Vaccine Not Very Effective This Season

Flu Cases Down Slightly

Brenda Goodman, MA
WebMD Health News

Reviewed by
Hansa D. Bhargava, MD

Jan. 16, 2015 — New flu cases were down slightly across the U.S. last week, but it’s still too early to know if the season has peaked, according to the CDC.

We’re 8 weeks into a particularly nasty flu season. People over 65 have been hardest hit. Seniors are being hospitalized for the flu at nearly twice the rate they were last year. And so far, 45 children have died as of the week ending Jan. 10, according to the agency.

The main strain that’s making people sick is different from the strains included in this year’s vaccine. As a result, many people are getting sick, even if they got their shots as recommended.

Forty-six states reported widespread flu activity — the same number as the week before. Three states – Alabama, Georgia, and Hawaii – reported significant levels, and Washington, D.C., and Alaska reported local flu activity.

Nineteen additional flu-related deaths of children were reported to the CDC last week. Deaths of children from the flu have ranged from 37 to 171 since 2004-2005, when they began to be reported, with the exception of the 2009-2010 H1NI flu pandemic.

The CDC doesn’t track adult deaths from the flu, but the proportion of deaths attributed to both pneumonia and the flu rose sharply this week and remains above the “epidemic” level, the agency said.

This season’s batch of flu shots cuts the risk of needing medical treatment for flu symptoms by about 23% on average, the CDC said Jan. 15. Compared to past seasons, that’s on the low side. Since the CDC started measuring how well flu vaccines work in 2005, their effectiveness has ranged from 10% to 60%.

Experts say it’s still a good idea to get the flu shot, even though protection from the current vaccine is spotty.

“It’s always better to have some protection rather than no protection,” says Len Horovitz, MD, a lung specialist at Lenox Hill Hospital in New York City. “Why would you opt for zero, even if the best you could do is 15% or 20%?”

Flu Cases Down Slightly


Horovitz sometimes encourages his patients, many of whom are at high risk for complications from the flu because of lung problems like asthma or COPD, to get the shot twice — once early in the season and again 5 to 6 months later.

The idea — which hasn’t been scientifically proven and is not endorsed by the CDC — is that the second shot might work like a booster to revive flagging immunity. Horovitz thinks that might be important for older adults and those with underlying medical conditions, who tend to have a poor response to vaccines in the first place.

“It’s a little bit controversial,” he admits. “I’m recommending it to people at high risk who were vaccinated in August or September, which was a while ago.”

Coverage Gap

During years when the vaccine is a good match for the flu virus strains that are making people sick, effectiveness is around 50%-60%. And it’s been in that range for the past four seasons.

But nearly three-quarters of the viruses that are making people sick this year are different than the strains included in the vaccine’s formula. That means people aren’t getting as much protection from the shot.

The CDC acknowledged the coverage gap last month, and last week the agency urged doctors and other health care providers to act quickly to prescribe antivirals — certain kinds of flu-fighting medications — if they suspect the infection.

How well flu vaccines work also varies by age. In general, older children and healthy younger adults get the most protection from the shots, because their immune systems are mature and working at their peak. Vaccines are less effective in young children and the elderly.

Based on early estimates, the CDC says this season, the vaccine appears to cut the risk of a doctor’s visit for the circulating H3N2 flu viruses by 26% in school-aged children, by 12% in adults ages 18 to 49, and by 14% for people 50 and over.

But getting vaccinated is “still the best thing you can do to prevent the flu,” says Seth Podolsky, MD. He’s an emergency medicine specialist at The Cleveland Clinic in Ohio.

Flu Cases Down Slightly

Coverage Gap continued…

“Just because the strains that are going around right now may not be a part of the vaccine, the strains that come around later in the season may very well be,” he says.

Be sure to wash your hands often, and stay home if you’re sick.

For those who are unlucky enough to come down with the flu’s telltale fever and body aches, Podolsky says urgency is key.

“If you are having significant symptoms, you want to get in touch with your doctor as soon as possible so that, potentially, antiviral medications can be prescribed. They’re most effective when given within the first 48 hours of having symptoms,” he says.

View Article Sources Sources


CDC Situation Update: “Summary of Weekly FluView, Jan. 16, 2015.”

CDC: Morbidity and Mortality Weekly Report, Jan. 16, 2015.

Len Horovitz, MD, Pulmonologist, Lenox Hill Hospital, New York, N.Y.

Seth Podolsky, MD, vice chairman, emergency medicine, The Cleveland Clinic, Cleveland, Ohio.

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