New studies suggest that the predominant strains of influenza that are prevalent this season have picked up nasty mutations, and this year’s flu vaccine is a “bad match.”
“From our lab-based research, it looks like a big mismatch,” said research co-author Scott Hensley, a professor of microbiology at the University of Pennsylvania’s School of Medicine at Perelman. Told to CNN..Hensley and his colleagues are of the H3N2 subtype influenza The virus looks for genetic mutations that occur in the virus as it spreads. Through their surveillance, they recently identified a new H3N2 “clade” or viral family tree division.
They named Clade “3C.2a1b.2a2” or 2a2 for short and posted their findings to the preprint database on Thursday (December 16th). medRxiv.. The study has not yet been peer-reviewed or published in scientific journals, mostly measuring only the antibody responses of 40 young and healthy individuals.However, research suggests that mutations carried by the new clade may cause this year’s flu. vaccination Hensley told CNN that the effect on H3N2 is low.
Related: Why is influenza vaccination less effective than other vaccines?
But that doesn’t mean that the flu shot you got didn’t help.
“Studies have shown that seasonal influenza vaccines consistently prevent hospitalization and death, even in years of high antigen mismatch,” the author wrote in a preprint. Therefore, even if this year’s flu shot does not match the predominant strain, the vaccine reduces the chance of serious illness or death.
So why is the newly identified 2a2 clade such a problem? Researchers have found that the virus in the clade has a mutation in the gene that encodes the protein hemagglutinin (HA) on the surface of the virus.
Influenza vaccine Immune system To recognize the HA protein that sticks out the flu virus like a lollipop Live science previously reported.. The problem is that the HA protein mutates so rapidly that its structure can change between the development of the influenza vaccine and the peak of the influenza season. Usually between December and February.. Of the four influenza subtypes (two influenza A viruses, H1N1 and H3N2, and two influenza B viruses from the Victoria and Yamagata strains) that are subject to the annual influenza pandemic, H3N2 mutates fastest. increase.
For this reason, influenza vaccination tends to be the least protective against H3N2, which has significantly impaired the effectiveness of past vaccines. The changes in the H3N2 virus this year are mutation Hensley told CNN that the vaccine was so weak during the 2014-2015 flu season that it provided only 6% protection against H3N2.
“Importantly, we found it antibody Induced by the 2021-202 Northern Hemisphere influenza vaccine, the new 2a2H3N2 clade is inadequately neutralized, “Hensley said. Tweet December 16th. “After vaccination, 55% of vaccinated people could not detect the level of neutralizing antibody against 2a2H3N2.”
This may partially explain the recent outbreak of influenza cases on the University of Michigan’s Ann Arbor campus, primarily caused by H3N2. Live science previously reported.. The surge affected more than 700 people, about a quarter of whom were vaccinated against the flu, CNN reported.
But not everything is lost. “Although cases of 2a2H3N2 infection are increasing rapidly in the United States and elsewhere in the world, other branches of H3N2 may predominate in the future,” the researchers write. “H1N1 or influenza B virus could predominate in the second half of the 2021-2022 season.”
You can read more about new research at CNN..
Originally published on Live Science.
Influenza vaccination can be a “bad match” for the predominant strain
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