Flu Cases Surge in US, Straining Hospitals Amid Peak Season

Flu cases have dramatically surged across the United States this December, with health officials warning of significant pressure on hospitals as the country experiences its worst influenza season since 2018. An estimated millions of Americans have fallen ill, leading to a sharp increase in flu-related admissions in emergency departments. According to the US Centers for Disease Control and Prevention (CDC), flu activity has escalated unexpectedly, prompting concerns about the capacity of health systems as winter reaches its peak.

The CDC’s data highlights a troubling trend, with outpatient visits and hospitalizations linked to flu-like illness rising sharply nationwide. This early surge mirrors patterns observed in Europe and parts of Asia, raising alarms that health systems might struggle if cases continue to climb into January and February, when flu activity typically peaks.

As of mid-December, the CDC estimated approximately 7.5 million flu cases and 81,000 hospitalizations in the US this season. At least 29 states are now reporting ‘high’ or ‘very high’ levels of influenza-like illness, according to the CDC’s FluView surveillance report. Some states, including New York, are facing record weekly flu admissions, indicating a severe strain on hospital resources.

Concerns Over Flu Severity and New Strain

The current spike follows the CDC’s classification of the 2024–25 flu season as a high-severity outbreak, marking the most severe influenza season since the 2017–18 period. That winter recorded 279 influenza-associated pediatric deaths, the highest number reported during a seasonal epidemic. Public health experts attribute the intensity of recent flu seasons to fluctuating vaccination rates, increased travel, and changes in immunity due to disruptions in virus circulation during the Covid-19 pandemic.

A new strain of influenza A, known as H3N2 subclade K, has emerged as the dominant flu virus in the United States. Citing CDC and international surveillance data, experts note that this strain accounts for around 90 percent of flu cases nationwide. It emerged earlier this year and has caused severe outbreaks in countries such as Japan and parts of Europe. The strain carries mutations that may allow it to partially evade immunity from previous infections and vaccinations. Nonetheless, vaccination remains effective in reducing severe illness, hospitalization, and death.

Public Health Response and Vaccination Efforts

Health officials caution that the worst of the flu season may still lie ahead, as peak flu activity typically occurs in January or February. Jennifer Nuzzo, an epidemiologist at Brown University, emphasized the challenge posed by simultaneous illnesses: “A lot of people are getting the flu at the same time, which is always tough. That can be harder than a season where cases are spread out.”

Officials continue to urge Americans who have not yet received a flu vaccine to do so, emphasizing that even late vaccination can mitigate the impact of the flu season. Although the H3N2 subclade K strain was not included in this year’s vaccine, experts affirm that the shot still provides critical protection against severe outcomes. By early December, approximately 130 million flu vaccine doses had been distributed, which is 13 million fewer than the previous year at the same time. This decrease raises concerns that reduced vaccine uptake could exacerbate the season’s impact.

“It’s not too late to get the flu vaccine,” health experts reiterated, highlighting that even partial protection can significantly benefit vulnerable populations, including young children, older adults, and individuals with underlying health conditions. As winter progresses, public health officials stress the importance of heightened awareness, vaccination, and early treatment in order to prevent hospitals from being overwhelmed by what could become an exceptionally challenging flu season.