Several researchers have stated that the main circulating influenza strain in the United States has mutated, noting that vaccines cannot prevent infection.
According to a pre-print study (pdf) by Scott Hensley, professor of microbiology at the University of Pennsylvania, flu shots do not protect against a mutated variant of the H3N2 influenza virus, or the most common one like vaccines. more consistent with the strain.
“From our laboratory tests, this looks like a major inconsistency,” Hensley told CNN on Thursday. He noted that his study only covered H3N2, adding that vaccines should protect against H3N2, H1N1, and two strains of influenza B.
“We have been observing this virus for several months,” he said, noting that influenza viruses are constantly mutating.
He told the network that the new H3N2 strain includes changes that allow it to avoid the antibodies that the body produces in response to vaccines.
The Centers for Disease Control and Prevention (CDC) previously incidence of influenza has dropped significantly in the past year with the advent of COVID-19. But Hensley noted that because of this phenomenon, the general population’s immunity to influenza is likely low.
“Once the restrictions associated with COVID-19 are eased or lifted, it is possible that influenza viruses will spread widely due to the lack of infection-induced immunity in the population over the past two years,” they write. “In recent weeks, a unique variant of H3N2 has“ circulated at elevated levels in the United States and other parts of the world, ”they continued.
In addition, they noted that “the H3N2 clade originated at the onset of the COVID-19 pandemic and almost completely supplanted other branches of H3N2 in Europe, Oceania, South Asia, West Asia and North America in 2021.”
The flu kills between 12,000 and 52,000 people a year, depending on the season, and up to 700,000 are admitted to hospital each year, according to figures provided by the CDC.
Earlier this month, the CDC said in a surveillance report that cases of influenza are on the rise in the United States.
“The number of influenza viruses detected by clinical and public health laboratories has increased in recent weeks. Most of the viruses detected are A (H3N2), ”the federal health agency said. “Most influenza A (H3N2) infections have occurred in children and young adults between the ages of 5 and 24; however, the proportion of infections occurring among adults aged 25 and over has increased in recent weeks. ”
More than 700 people have been affected by the flu outbreak at the University of Michigan, according to local health officials. The CDC said it is aware of flu outbreaks at universities and colleges in several states, adding that influenza vaccination coverage is low.