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Partially effective flu vaccine better than nothing, experts say

Thursday, January 16, 2020
By Brian P. Dunleavy
M. Anthony Moody, MD

Four strains of the influenza virus have been identified through lab tests as circulating across the United States so far this flu season. This year's vaccine has two of them.

(UPI) - Creating the annual flu vaccine may not be an exact science, but drugmakers working in tandem with epidemiologists around the world seem to get it right more often than not.

Four strains of the influenza virus have been identified through lab tests as circulating across the United States so far this flu season.

The vaccines approved for use this year cover at least two of them, officials say, but they won't know exactly how effective the shot has been until the season is over.

"There is some concern about different kinds of vaccine mismatch, but it is hard to know in real time how effective the vaccine is," Tony Moody, an associate professor of pediatric infectious diseases and immunology at Duke University Medical Center, told UPI. Moody is one of the principal investigators for Duke's Collaborative Influenza Vaccine Innovation Centers, where he works to identify potential influenza vaccine candidates.

"Regardless, we know that even in years when the vaccine is only partially effective, it is still more effective than not getting the vaccine -- so we recommend that people get the current vaccine, even if it is not perfect," he said.

According to data from the U.S. Centers for Disease Control and Prevention, over the past decade, the approved vaccines -- which are developed for each flu season by private manufacturers -- have been at least 40 percent effective at preventing hospitalizations from lab-confirmed cases of influenza. At their best, though, the shots have been 60 percent effective.

Notably, vaccine effectiveness has declined in each of the past four flu seasons for which data are available: from 48 percent in 2015-16 to 40 percent in 2016-17, 38 percent effective in 2017-18 and 29 percent effective in 2018-19. Preliminary data on the effectiveness of this year's shot will be available in February, the CDC said.

"A flu vaccine is the first and best defense against influenza, and CDC recommends ongoing vaccination as long as influenza viruses are circulating," a representative of the agency said. "Flu activity is typically highest between December and February, although it can last as late as May. Even if we are at the peak of this season, there are still many more weeks of activity to come -- and the flu vaccine can help reduce illness and protect against severe complications that can lead to hospitalization or even death. Even during seasons when vaccine viruses and circulating viruses are not well-matched, the flu vaccine may still provide protection."

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