this season express HA genes belonging to clade 3C.2a1b.2a.2 and this clade has been split into multiple subclades. All A(H3N2) viruses collected thus far in the U.S. this season express HA genes belonging to 6B.1A.5a.2 but this clade has been split into the 2a and 2a.1 subclades. The vast majority of A(H1N1)pdm09 viruses collected in the U.S. To reflect the genetic diversity of the HA genes in recent A(H1N1)pdm09 and A(H3N2) viruses, new subclades have been designated. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans.ĬDC genetically characterized 2,560 influenza viruses collected since October 2, 2022. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines. viruses submitted from state and local public health laboratories according to the Right Size Roadmap submission guidance.
There are also prescription flu antiviral drugs that can be used to treat flu illness those need to be started as early as possible.ĬDC performs genetic and antigenic characterization of U.S. 
CDC continues to recommend that everyone ages 6 months and older get an annual flu vaccine as long as flu activity continues.
All viruses collected and evaluated this season have been susceptible to the influenza antivirals peramivir, zanamivir, and baloxavir, and all viruses except for one (> 99.9%) have been susceptible to the influenza antiviral oseltamivir. The majority of influenza viruses tested are in the same genetic subclade as and antigenically similar to the influenza viruses included in this season’s influenza vaccine. CDC estimates that, so far this season, there have been at least 26 million illnesses, 290,000 hospitalizations, and 18,000 deaths from flu. Four influenza-associated pediatric deaths that occurred during the 2022-2023 season were reported this week, for a total of 138 pediatric flu deaths reported so far this season. Of the 34 influenza A viruses detected and subtyped during week 12, 58.8% were influenza A(H3N2) and 41.2% were influenza A(H1N1). During week 12, 67.2% of viruses reported by public health laboratories were influenza A and 32.8% were influenza B. The number and weekly rate of flu hospital admissions remain low. Nationally, outpatient respiratory illness is below baseline, and eight of 10 HHS regions are below their respective baselines. Seasonal influenza activity remains low nationally.
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