Flu activity rises slightly as winter storm impacts spread
Flu activity has ticked back up slightly in the US, thanks to a very small increase in infections caused by influenza B — viruses distinct from the new subclade K strain that’s been the biggest player this flu season so far, reports BritPanorama.
According to Dr. Caitlin Rivers, an epidemiologist, “We are seeing a second peak, a second rebound from flu. It’s concentrated in school-age children,” specifically those aged 5 through 17. Rivers emphasized that children often register new trends in flu activity first.
She noted, “Children and kids are always the first to register new trends. So I do think that the increase will hit adults as well, but for now, it’s really concentrated in kids.” This pattern mirrors last year’s flu season in the US, when cases surged for a second time in late February after an initial decline.
Rivers attributes some of the current trends to the recent winter storm that affected about half the US, which may exacerbate the spread of influenza.
Recent data reported Friday by the US Centers for Disease Control and Prevention shows that B strains are edging up, increasing by less than a full percentage point over the previous week, while flu A activity is holding steady. Whether this signals the start of a spring wave of influenza B remains uncertain, Rivers added.
Influenza B strains belong to a different family of viruses. Even individuals who have had the flu once this season may contract a different strain. This year’s flu vaccine is designed to protect against two A strains and one B strain, thereby offering some level of defense against severe illness and hospitalization.
Both flu A and B typically induce similar symptoms such as high fever, sore throat, cough, body aches, and fatigue, as well as being treatable with antivirals. Overall, flu activity remains brisk, led by the recently emerged subclade K, an influenza A strain from the H3N2 lineage. Seasons dominated by H3N2 strains tend to be more severe.
Among laboratory test results reported to the CDC during the week ending January 24, 87% involved A strains of the flu, while roughly 13% were attributed to B strains. The CDC’s national map indicates a high burden of influenza, with 29 states reporting high or very high flu activity, while another ten states report moderate activity.
Last week, eight more flu deaths in children were documented, increasing the season’s total to 52. Flu remains the dominant respiratory infection compared to Covid-19 and respiratory syncytial virus (RSV), although activity from both Covid and RSV is on the rise.
The persistent cold weather and influenza B virus variations may continue to impact health systems throughout the winter months, adding strain to public health responses across the country.
