The current flu season, which has been relatively mild so far, is expected to become more severe in the coming weeks due to a newly identified strain. Medical experts indicate that this strain emerged after the production of the current influenza vaccine, although they maintain that vaccination remains the most effective means of protection.
Data from the United Kingdom, as reported by the National Health Service, reveals that the new strain has led to the highest rate of flu hospitalizations observed for this time of year. The strain, known as subclade K, first appeared in Australia at the end of its flu season and has since been detected in Japan and the United States, according to Lisa Sollot, respiratory disease program coordinator for the Virginia Department of Health.
The effectiveness of the current vaccine has been called into question. Figures from the UK indicate that it is approximately 32-39% effective in preventing flu infections, though it appears more effective in children, with rates between 72-75%, as noted by the University of Virginia. Frederick G. Hayden, a professor at the UVA School of Medicine and a member of the Division of Infectious Diseases and International Health, co-authored an article in the Journal of the American Medical Association that discusses these findings. He emphasized that the emergence of subclade K, which is a subtype of the strain that contributed to a particularly severe flu season last year, suggests this season may also be severe.
A report from the Centers for Disease Control and Prevention (CDC) dated December 11 supports these concerns, stating that the current influenza season in the United States is accelerating. The report highlights that the 2024-25 influenza season, driven largely by influenza A H1N1 and H3N2 viruses, has shown high severity across all age groups, including a notably high number of pediatric deaths.
In a statement, Hayden noted, “Unfortunately, we are seeing the circulation of a new variant of H3N2 virus for which our vaccines may be somewhat less effective. However, available vaccines will reduce the risk of serious illness and potentially the spread of this virus.”
Sollot further noted that historically, there have not been high-severity flu seasons in consecutive years. She cautioned that low vaccination rates combined with the emergence of subclade K could lead to a particularly challenging season, although it is difficult to predict the exact severity.
Currently, vaccination rates in Virginia stand at approximately 28% across all age groups, with the lowest rate of 20.6% for individuals aged 5-17 and the highest at 39.8% for those aged 50 and older. Data from the CDC concerning last season revealed that around 90% of children who succumbed to the flu were unvaccinated, and 50% of those children had no underlying health conditions.
“These statistics are truly alarming,” Sollot stated. “We urge everyone to get vaccinated, practice good hand hygiene, and stay home when feeling unwell.” The CDC recommends influenza vaccination for everyone aged six months and older, with only rare exceptions.
As the flu season evolves, public health officials continue to stress the importance of vaccination and preventive measures to combat the potential impact of this new strain.
