This winter, the Centers for Disease Control and Prevention (CDC) and the Department of Health and Human Services are facing criticism for their lack of communication regarding the ongoing respiratory season, which is heavily influenced by influenza, respiratory syncytial virus, and COVID-19. While these agencies usually provide extensive guidance, this year’s updates have been sparse, often found only through social media channels that do not adequately stress the importance of vaccination in preventing severe disease.
The flu season is intensifying, largely due to a newly drifted variant of the H3N2 influenza A virus known as Subclade K. This variant is currently responsible for 90% of circulating H3N2 viruses in the United States between late September and early December. Typically, H3N2 seasons are more severe, and the CDC has reported approximately 7.5 million illnesses, 81,000 hospitalizations, and 3,100 deaths, including eight pediatric fatalities. Influenza infections are reportedly rising or remaining high in 29 states, with the reproductive number indicating active virus spread.
Subclade K presents a significant drift with seven mutations in its hemagglutinin protein. While these changes allow the virus to partially evade immunity from previous infections and vaccinations, experts note that this does not mean the vaccine is entirely ineffective. Moreover, early data indicate that despite limited recognition of Subclade K by antibodies generated from this year’s vaccine reference strain, there is still protection available.
Initial estimates from the UK suggest that the current flu vaccine is 70%-75% effective for children and 30%-40% for adults, which aligns with effectiveness rates seen during previous seasons, even in cases of drift. Although immunity may diminish as the season continues, these figures underscore the vaccine’s role in preventing severe illness. Therefore, the adage rings true: getting vaccinated offers better protection than opting out entirely.
Despite these findings, only 42% of U.S. adults and children have been vaccinated against the flu this season, representing a considerable gap that healthcare professionals can still address. Even in a drift year, the flu vaccine remains the most effective tool for reducing the risk of hospitalization and death, transforming a potentially serious illness into a far more manageable one.
Importantly, Subclade K has no known mutations that increase its severity, and it is still effectively treated with antiviral medications such as oseltamivir. This means that although the virus has mutated, the available treatments retain their efficacy.
Clinicians have a crucial role in dispelling misconceptions surrounding the vaccine’s effectiveness. As patients hear about “new strains” and “mismatch,” many may assume that the vaccine is no longer effective. Healthcare providers need to clarify this misconception, emphasizing that it is not too late to get vaccinated. Clear communication regarding the significance of continued vaccination and the importance of seeking treatment when symptoms arise—such as fever and cough—can lead to better outcomes.
This flu season should not incite panic but rather motivate action. With rising cases of Subclade K, an effective vaccine is still available, and treatments remain potent. Increased vaccination rates, timely antiviral treatments, and transparent communication will help mitigate the impact of this season. Ultimately, our proactive measures can shape the trajectory of the flu season and ensure better health outcomes for the community.