Flu Activity Remains High Heading Into 2023

Although influenza (flu) is declining in most areas, case numbers remained high as the season entered the new year, according to the weekly U.S. Influenza Surveillance Report from the U.S. Centers for Disease Control and Prevention (CDC).

For the week ending January 7, 8.6% of clinical lab tests were positive for flu and 4.0% of visits to a health care provider were for respiratory illness, an above-the-baseline percentage. There were also 12,409 patients with the flu admitted to hospitals that week, as well as an above-the-threshold percentage of deaths (13.1%) attributed to pneumonia, flu, or COVID-19. The CDC estimates that, so far this season, there have been at least 24 million illnesses, 260,000 hospitalizations, and 16,000 deaths from the flu alone.

Of influenza A viruses detected and subtyped during the week, 72% were influenza A(H3N2) and 28% were influenza A(H1N1). Most influenza viruses tested were in the same genetic subclade as and antigenically similar to the influenza viruses included in this season’s flu vaccine. All viruses collected and evaluated this season have been susceptible to the influenza antivirals oseltamivir, peramivir, zanamivir, and baloxavir.

The cumulative hospitalization rate was 1.8 times higher than the highest cumulative in-season hospitalization rate observed for week 1 during previous seasons going back to 2010–2011. However, this in-season rate is still lower than end-of-season hospitalization rates for all but four pre-COVID-19 pandemic seasons.

The CDC continues to recommend that everyone age 6 months and older get an annual flu vaccine while the current flu season remains active.