The United States is preparing for what could be another record-setting flu season, as a new variant of the virus spreads globally, raising alarm among health officials.

Experts in the field anticipate that the 2025-2026 respiratory virus season might match or surpass last year’s figures, which saw an estimated 47 to 82 million individuals falling ill and between 27,000 to 130,000 fatalities, marking it as the most severe in nearly ten years.

This season was also noted as one of the most intense flu outbreaks in over 15 years, characterized by extremely high rates of hospital admissions, outpatient clinic visits, and child fatalities. This was largely due to the aggressive nature of the circulating strains and suboptimal vaccination coverage.

A nationwide epidemic trend map indicates that flu cases are either increasing or already on the rise across all reporting states in the US.

Influenza currently accounts for two percent of positive laboratory tests from all tested respiratory specimens.

Moreover, doctor visits for flu-like symptoms have slightly increased to 2.1 percent of all consultations this week, suggesting an early uptick in flu activity. The surge is primarily driven by children and younger adults.

The new flu variant that is currently raising concerns for its ability to partially evade the immune system and the seasonal vaccine is a variant of the existing H3N2 influenza A virus.

The strain, which has been dubbed ‘Subclade K’, has spread rapidly in several countries, including Japan, the UK and Canada and it is expected to hit the US in the coming weeks.

Seasonal flu vaccines are designed to protect against the three main groups of flu Type A and B viruses that research indicates are most likely to spread and cause illness among people during the upcoming flu season. 

The US is gearing up for yet another record-breaking flu season with a new variant spreading globally adding further cause for concern (stock image)

Currently, the recommended US flu vaccine does not protect against Subclade K, and is only designed to block the influenza A viruses, H1N1 and H3N2, and the influenza B virus, Victoria.

At the same time, flu vaccination coverage in the US has been slipping steadily since the COVID‑19 pandemic, according to recent CDC data. 

In the 2023–24 season, just 55.4 percent of children (ages six months to 17 years) received a flu shot, down two percentage points from the prior year and 8.3 points below pre‑pandemic levels in 2019–20.

At the same time, only 44.9 percent of adults were vaccinated, also two points lower than in 2022–23. 

Subclade K is thought to have emerged at the tail end of Southern Hemisphere’s flu season (which is May through October as opposed to October through May in the US) and early data from the UK and Japan suggests it is already represented in most flu samples.

It has also been detected in North America, although it is unclear what proportion of samples it currently accounts for there. 

Due to the recent record-breaking government shutdown and internal staffing changes, up-to-date national flu activity information from the CDC was temporarily unavailable. 

The government organization resumed updating its flu surveillance reports after the shutdown ended on November 12, 2025. 

From November 3 to 9, the CDC reported that there were 1,665 influenza-associated hospitalizations, which marks a five percent increase from the previous week.

The hospitalization rate is currently one per 100,000 people. 

At the peak of last year’s flu season, that rate was 13.5 per 100,000 people

The most frequently reported influenza strain is H3N2.

Overall, the nationwide level for flu and respiratory syncytial virus (RSV) is low but both are increasing.

In Alabama and New Hampshire, levels for respiratory illnesses are moderate, where as elsewhere across the country they are low to very low.

As of yet, there has been no reporting from the CDC on the Subclade K strain.  

In Alabama and New Hampshire, levels for respiratory illnesses are moderate, where as elsewhere across the country they are low to very low

The CDC uses data from emergency department visits to model epidemic trends. This model helps reveal if the number of new respiratory infections is growing or declining in each state

Subclade K flu symptoms are similar to other flu strains, with high fever, severe body aches, and fatigue being common.

The main concern is its rapid spread and ability to bypass some immunity, meaning vaccinations might not offer adequate protection.

Anecdotal reports suggest in Australia it caused more severe body aches, longer-lasting tiredness and symptoms come on more suddenly.

Inflammation from the flu can make it difficult for the lungs to transfer enough oxygen to the rest of the body, raising the risk of deadly complications, including death.

Flu can lead to pneumonia, which can cause respiratory failure, deadly sepsis, or inflammation of the heart, brain and muscles.

It can also make existing chronic conditions, such as heart disease and asthma worse, and require hospitalization.

Experts have also warned the reason it may spread more quickly is because it has a higher reproduction rate.

Despite this, the CDC and other health bodies warn that immunizations are still the best way to prevent serious illness from all strains of the flu.

Everyone aged six months and older is advised to be up to date with the flu vaccine annually, each season. 

In week 45 of the influenza season (November 3 to 9) there were 1,665 laboratory-confirmed influenza-associated hospitalizations, which marks a 5 percent increase form the previous week

A visual showing flu vaccination intent in the US among adults. Plummeting vaccination rates were cited as one of the main reasons for a rise in flu cases in the US for the 2024-2025 season

Older residents in nursing homes are at heightened risk of severe illness and death from any one of the three viruses due to their weakened immune systems.

During the 2021-2022 flu season, the death rate for people 65 years and older was around 7.4 per 100,000 population, compared to 0.1 per 100,000 people among those aged 18 to 49 years.

Plummeting vaccination rates were cited as one of the main reasons for a rise in flu cases in the US for the 2024-2025 season.

The flu vaccination rate for US children declined from about 64 percent five years ago to 49 percent. 

Childhood vaccinations in general have been declining, driven by online misinformation and the political schism that emerged around COVID-19 vaccines.

Meanwhile, health secretary Robert F. Kennedy Jr. has also echoed some of the rhetoric of antivaccine activists since taking over as the nation’s health secretary.