Influenza Season Persists Across the US

According to the U.S. Centers for Disease Control and Prevention (CDC), the U.S. is experiencing a sustained period of elevated influenza activity, with some regions witnessing increases, indicating that the respiratory illness season is still in full swing. The latest surveillance data reveals a stable national percentage of respiratory specimens testing positive for influenza, with notable upticks in regions 3 (Mid-Atlantic), 5 (Great Lakes), and 7 (Central). Despite minor fluctuations in virus types, influenza A(H1N1)pdm09 remains the predominant strain across the country, with influenza B viruses on the rise in specific areas.

The CDC’s characterization of 1,725 influenza viruses since October 1, 2023, aims to monitor the similarities between circulating strains and vaccine references, as well as to track viral evolution and antiviral resistance. This analysis is crucial for ensuring the effectiveness of current vaccines and treatments against the evolving virus.

Outpatient visits for respiratory illness, tracked by the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet), have consistently remained above the national baseline since November, reflecting widespread influenza activity alongside other respiratory viruses. The CDC emphasizes the importance of integrating these data with other surveillance sources for a comprehensive understanding of respiratory illness dynamics.

Hospitalization rates, particularly among vulnerable groups such as the elderly, non-Hispanic Black individuals, and those with underlying medical conditions, highlight the severe impact of the current flu season. With over 15,000 hospitalizations reported and a cumulative rate that ranks third highest since 2010, the urgency for vaccination and antiviral treatments is more pronounced. The CDC continues to recommend annual flu vaccinations for everyone aged 6 months and older and prompt antiviral intervention for high-risk individuals to mitigate the ongoing influenza threat.