Flu Vaccine Could Work as Well as Last Year's Shot: Study

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Monday, December 18, 2017

MONDAY, Dec. 18, 2017 (HealthDay News) -- As the flu barrels across the United States, the good news is that this year's vaccine may work better than many expected.

The flu has reached epidemic proportions in seven of the 10 regions in the country, according to Lynnette Brammer, an epidemiologist in the U.S. Centers for Disease Control and Prevention's influenza division.

Even more troubling, the same, more severe H3N2 flu strain that was around last year is circulating again this year, she said.

That concerned flu experts who had watched the vaccine show only 10 percent effectiveness against the H3N2 strain that circulated in Australia, where the flu season has just ended.

But a recent report in the journal F1000 Research found the Australian strain of H3N2 is not identical to the predominant virus circulating in the United States.

"The majority of the viruses are well-covered by the vaccine," said lead researcher Dr. Slobodan Paessler, a professor in the department of pathology at the University of Texas Medical Branch in Galveston.

"There are some minor groups of viruses that are not well-covered," he added.

"The current vaccine in the U.S., in contrast to the Australian [vaccine], will work because we have most of the American H3N2 viruses, rather than the Australian one," Paessler explained.

Using a computer program to compare the viruses used in the vaccine to the circulating strains of flu in the United States, Paessler and his colleague, Veljko Veljkovic from Biomed Protection in Galveston, found they are a good match. That means the vaccine should be as effective as it was last year.

Last year, the vaccine was 43 percent effective against the H3N2 virus and 48 percent effective overall, according to the CDC.

While vaccine effectiveness can vary from year to year, recent studies show that flu vaccination reduces the risk of flu illness by between 40 and 60 percent among the general population.

Brammer said that other types of flu are around, including influenza A H1N1 and a couple of influenza B viruses. The flu vaccine is very effective against these strains, she said.

"The vaccine doesn't work as well for H3N2 as we would like, but does work for some, and it may provide partial protection. And there are a lot of H1N1 and B viruses out there," she said.

And even though the vaccine is only partially effective, it still will prevent many people from coming down with flu and make it milder for those who catch it, Brammer said.

If you do get flu, Brammer suggests taking antivirals such as Tamiflu to reduce the number of days you are sick. The drug works best when taken right when you get sick, so seeing your doctor early is a good move, she said.

The CDC also advises people to wash their hands often to prevent spreading flu and to stay home if they're sick so they won't spread it to others.

The flu is being seen throughout the country and is very active in Alabama, Alaska, Arizona, Georgia, Kentucky, Louisiana, Mississippi, South Carolina, and Texas, the CDC reports.

And CNN reports that the CDC says more than 6,000 people have tested positive for the flu this year. That number is twice that of reported cases at the same time last year.

It's too early to tell if H3N2 will continue to be the predominant strain or whether H1N1 will surpass it, Brammer said.

Usually, a H3N2 portends a severe flu year, but mild H3N2 years have also occurred, she added.

SOURCES: Lynnette Brammer, M.P.H., epidemiologist, influenza division, U.S. Centers for Disease Control and Prevention; Slobodan Paessler, D.V.M., Ph.D., professor, department of pathology, University of Texas Medical Branch, Galveston; Nov. 29, 2017, F1000 Research

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