Fearing a “double whammy” of illnesses this winter, health experts, including those at the CDC are urging the public to not only get vaccinated against COVID-19 but also against the flu.
However, new research released Wednesday as a pre-print, suggests that one of the main strains of the influenza virus that’s now going around has mutated and that this year’s flu vaccine doesn’t seem to be doing much to prevent infection.
“From our lab-based studies, it looks like a major mismatch,” University of Pennsylvania microbiology professor Scott Hensley, who helmed the study, tells CNN.
The study notes that “antibodies elicited by the 2021-2022 Northern Hemisphere influenza vaccine poorly neutralize the new H3N2 strain,” the most prominent circulating strain of the four strains that the vaccine protects against.
Generally, influenza vaccines protect against four different strains of the flu: H3N2, H1N1, and two strains of influenza B. Dr. Hensley’s study only covers H3N2, the primary circulating strain of the flu this season.
Another thing we must take into account is that because flu strains are constantly changing every year, vaccine strains are chosen early, way in advance of the flu season. So by the time the vaccines are produced, the major strain they are supposed to work against may have already mutated.
This may also explain an outbreak of flu at the University of Michigan last month that affected more than 700 people. More than 26 percent 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.
“We have been monitoring this virus for several months,” Hensley 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.
“Studies have clearly shown that seasonal influenza vaccines consistently prevent hospitalizations and deaths even in years where there are large antigenic mismatches,” Hensley and colleagues wrote in the report.
