Seasonal influenza activity is on the rise across most regions in the United States, marking the start of what is shaping up to be an active flu season. Recent data from the CDC indicates that this week saw an increase in the percentage of respiratory specimens testing positive for influenza, alongside heightened levels of flu-related outpatient visits, hospitalizations, and even deaths compared to the previous week.
For the current flu season, the CDC has reported the first pediatric death associated with influenza, highlighting the potentially serious nature of the virus. This week also noted that Influenza A(H3N2) continues to be the most prevalent strain, with 525 of the 547 influenza viruses reported categorized as type A. A significant portion of these A viruses, approximately 86%, belong to the A(H3N2) subtype.
Among the A(H3N2) viruses collected since late September, 89% have been classified as a newly identified subclade, known as “H3N2 subclade K.” Notably, these variants are antigenically drifted from the strains used in the current influenza vaccines, which could impact vaccine effectiveness. However, even with this drift, vaccination remains crucial. The CDC emphasizes the benefits of the flu vaccine, which includes protection against severe illness, hospitalization, and death, as well as potential protection from other circulating strains represented in the vaccine.
Current estimates suggest that between 2.9 million illnesses, 30,000 hospitalizations, and 1,200 flu-related deaths have occurred this season to date. The importance of the flu vaccine cannot be understated, as more than 127 million doses have been distributed this season already, with the CDC recommending annual flu vaccinations for everyone aged six months and older.
While the flu activity is indeed rising, there is a cautious optimism as the seasonal pattern indicates that such increases are typical for this time of year. It is essential for the public to stay informed and to consider timely vaccination as a protective measure against influenza and its associated complications. The ongoing surveillance and reporting by the CDC provide critical insights as we navigate through this influenza season.