US Faces Potentially Severe Flu Season, Expert Warns

Experts warn that the United States may experience a particularly severe influenza season, with limited effectiveness of current vaccines against the circulating subclade K variant of the virus. Dr. Frederick G. Hayden, a professor emeritus at the University of Virginia School of Medicine, highlighted the potential risks associated with this year’s flu season, which is already showing signs of intensity.

The subclade K variant is part of the influenza A lineage responsible for the 1968 flu pandemic, which claimed approximately 100,000 American lives and around one million globally. As this strain, known as H3N2, begins to circulate more widely, especially during the holiday season and as schools reopen after winter break, public health officials are on high alert.

Concerns About Vaccine Mismatch

Dr. Hayden expressed his concerns in a recent article published in JAMA, co-authored with British virologist Maria Zambon, Ph.D.. He noted that the available vaccines do not effectively match the circulating virus strain. Early reports from the United Kingdom indicate that flu hospitalizations are at record highs for this time of year, signifying the potential severity of the flu season.

In Australia, where the flu season has concluded, the overall burden was deemed moderate. However, the emergence of the K subclade extended its duration and impact. In the United States, flu activity remained low until Thanksgiving, despite the K variant’s presence. Yet, an update from the Centers for Disease Control and Prevention (CDC) on December 11, 2023, indicated that the virus’s spread is accelerating, with expectations of worsening conditions in the coming weeks.

Vaccination Recommendations and Precautions

The mismatch between the virus and available vaccines raises serious concerns. Vaccine manufacturers must prepare formulations well in advance, relying on predictions from organizations like the CDC and the World Health Organization. Initial analyses from the UK suggest that adult vaccines are only 32-39% effective in preventing hospitalizations related to influenza, while children’s vaccines show better results at 72-75% effectiveness.

Despite the reduced effectiveness, vaccination remains crucial. The CDC recommends that everyone aged six months and older receive the flu vaccine, particularly vulnerable populations such as children, seniors, and individuals with underlying health conditions. Dr. Hayden emphasized the importance of vaccination, stating, “Getting vaccinated as soon as possible remains the single most important action people can do to protect themselves and their families.”

In addition to vaccination, Dr. Hayden advises common-sense measures to prevent transmission, such as avoiding close contact with sick individuals, wearing masks in crowded settings, and practicing good hand hygiene. For those at higher risk, considering antiviral medications for prevention upon exposure can be beneficial. Prompt antiviral treatment can also shorten the duration of illness and mitigate complications, which can help alleviate pressure on healthcare systems.

As the flu season progresses, public health officials and medical experts urge communities to remain vigilant and proactive in their health measures, especially as the subclade K variant poses a significant threat to public health.