Influenza cases in the United States have surged significantly in December 2023, following the most severe flu season since 2018, according to the Centers for Disease Control and Prevention (CDC). While the total number of infections for the season remains uncertain, more than 3,100 people died from the virus in the year ending August 2023. The CDC reports that as of December 20, there have been an estimated 7.5 million influenza cases and 81,000 hospitalizations, marking a 25% increase in reported cases over the previous week.
The rise in flu cases coincides with a particularly challenging flu season. The 2024-2025 season has already recorded 279 influenza-associated pediatric deaths, the highest number reported during a seasonal influenza epidemic. Epidemiologists are urging individuals who have not yet received a flu vaccine to do so. Jennifer Nuzzo, an epidemiologist at Brown University, emphasized the importance of vaccination, particularly for vulnerable populations such as young children and older adults.
“The bottom line for people is that if they haven’t gotten vaccinated against the flu, they should get vaccinated,” Nuzzo stated. The emergence of a new variant, known as subclade K, has contributed to the early onset of the flu season in Europe, which has reported “high or very high influenza activity” in December.
In the United States, thirty-two states are experiencing a “high or very high” number of flu illnesses. Nuzzo remarked, “A lot of people are getting the flu at the same time, which is always tough. That is actually tougher than a situation in which people get it and it’s spread out over a longer period.” The concentrated spike in cases could strain healthcare resources, as hospitals may struggle to accommodate the surge in patients seeking care.
Concerns are also growing regarding public willingness to receive the flu vaccine. The CDC, under the leadership of health secretary Robert F. Kennedy Jr., has cancelled its campaign encouraging vaccination, which may contribute to lower uptake this season. At the start of December, approximately 130 million flu vaccines had been distributed in the U.S., which is 13 million fewer than the same time last year.
“It’s completely incredulous to me that after experiencing the worst flu season for kids on record, we could head into this flu season with anything but a robust plan to encourage people to get vaccinated,” Nuzzo added. There are also concerns that the new vaccine may offer reduced protection against the latest variant. Nuzzo cautioned, “We have some reason to think that the protection may be lower, but it’s likely still going to give you some important protection.”
Public awareness of flu testing options is another area of concern. Nuzzo noted that many individuals may not realize they can obtain at-home flu tests from pharmacies. “There are some people who might benefit from medication if they tested positive, but that medication needs to be given very soon after symptoms start,” she explained.
As flu season progresses, the combination of rising case numbers and vaccine hesitancy poses a significant challenge for public health officials. The urgency to promote vaccination and increase awareness about available resources is critical to mitigating the impact of the ongoing flu epidemic in the United States.
