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Source: https://www.cnn.com/2021/12/16/health/flu-vaccine-mismatch/index.html
Flu vaccines don't match the main circulating flu virus strain, researchers find
By Maggie Fox, CNN
Updated 8:55 PM ET, Thu December 16, 2021
(CNN)One of the main circulating influenza viruses has changed and the current flu vaccines don't match it well any more -- an indication they may not do much to prevent infection, researchers reported Thursday. But they are still likely to prevent severe illness.
"From our lab-based studies it looks like a major mismatch," Scott Hensley, a professor of microbiology at the University of Pennsylvania who led the study, told CNN.
It's bad news for the vaccine, he said. Influenza vaccines protect against four different strains of the flu: H3N2, H1N1 and two strains of influenza B. Hensley's study only covers H3N2, but that happens to be the main circulating strain.
The vaccine mismatch may help explain an outbreak of flu at the University of Michigan last month that affected more than 700 people. More than 26% of those who tested positive had been vaccinated against flu -- the same percentage as those who tested negative. That indicates the vaccine was not effective in preventing infection.
It's what flu viruses do, Hensley said. "We have been monitoring this virus for several months," he said. Flu viruses mutate all the time—far more than other viruses, including the coronavirus. And different variations can circulate at the same time. But this version of H3N2 has changes that help it escape the antibodies the body makes in response to vaccines...
Flu vaccines don't match the main circulating flu virus strain, researchers find
By Maggie Fox, CNN
Updated 8:55 PM ET, Thu December 16, 2021
(CNN)One of the main circulating influenza viruses has changed and the current flu vaccines don't match it well any more -- an indication they may not do much to prevent infection, researchers reported Thursday. But they are still likely to prevent severe illness.
"From our lab-based studies it looks like a major mismatch," Scott Hensley, a professor of microbiology at the University of Pennsylvania who led the study, told CNN.
It's bad news for the vaccine, he said. Influenza vaccines protect against four different strains of the flu: H3N2, H1N1 and two strains of influenza B. Hensley's study only covers H3N2, but that happens to be the main circulating strain.
The vaccine mismatch may help explain an outbreak of flu at the University of Michigan last month that affected more than 700 people. More than 26% of those who tested positive had been vaccinated against flu -- the same percentage as those who tested negative. That indicates the vaccine was not effective in preventing infection.
It's what flu viruses do, Hensley said. "We have been monitoring this virus for several months," he said. Flu viruses mutate all the time—far more than other viruses, including the coronavirus. And different variations can circulate at the same time. But this version of H3N2 has changes that help it escape the antibodies the body makes in response to vaccines...
