Study: Minor Flu Strains Could Cause More Harm Than Originally Thought

Minor strains of the flu, which are not typically targeted by the flu vaccine, can cause more harm than originally thought, according to a recent study.

“A flu virus infection is not a homogeneous mix of viruses, but, rather, a mix of strains that gets transmitted as a swarm in the population,” researchers explained.
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In order to better understand the genetic diversity of minor strains of the Influenza A virus, as well as how the virus is transferred between individuals, researchers conducted genome deep sequencing of nasal cavity swabs taken from confirmed cases from the 2009 Hong Kong flu pandemic.

Overall, researchers found that while most individuals carried the dominant strain of the virus—H1N1 or H3N2—they all carried additional minor strains and variations of the major and minor strains as well.

“We were able to look at the variants and could link individuals based on these variants,” they said. “What stood out was also how these mixes of major and minor strains were being transmitted across the population during the 2009 pandemic—to the point where minor strains became dominant.”

“Current vaccines target the dominant strains, because they are the ones that seem to infect the largest number of individuals. But our findings reveal an ability of minor strains to elude these vaccines and spread the virus in ways not previously known,” they concluded.

—Michael Potts

Reference:

  1. New York University. Scientists find minor flu strains pack bigger punch [press release]. January 4, 2015. http://www.nyu.edu/about/news-publications/news/2016/01/04/scientists-find-minor-flu-strains-pack-bigger-punch.html.
  2. Poon LLM, Song T, Rosenfeld R, et al. Quantifying influenza virus diversity and transmission in humans. Nature Genetics. 2016 January [epub ahead of print]. doi:10.1038/ng.3479.