It could be a nasty flu season, thanks to a new mutated strain and falling vaccination rates. Read on for what the experts are predicting about the expected severity of this year's flu season.

New Flu Variant Likely to Usher in Rough Season for the U.S.

Health experts are warning that the U.S. could be in store for its second consecutive severe flu season. Last winter's season saw the highest rate of hospitalizations at the hands of the flu in almost 15 years. At least 280 pediatric deaths were blamed on influenza last season, demonstrating the severity of the strain.

A new mutated strain known as subclade K is driving an early surge of flu cases in Japan, Canada, and the United Kingdom (UK). Combine these early signs with declining flu vaccination rates, and it is easy to see why the healthcare community is growing concerned about what lies ahead.

Not all of the news is bad. Early data is offering hope that this year's flu shots are offering a good deal of protection against being hospitalized with the new variant. This data is most pronounced in pediatric cases. Unfortunately, more Americans are choosing to skip out on the vaccine this year, according to data from IQVIA.

A new FluView report from the U.S. Centers for Disease Control and Prevention (CDC) is offering a mixed bag of news. Although flu activity is currently low across the U.S, it is starting to spike in some states.

The bulk of the flu viruses identified thus far this season have been from an A strain known as H3N2. Roughly half of these cases have come from subclade K, the same variant that triggered a rough flu season over the summer in the Southern Hemisphere. This particular variant was not on the scene when scientists chose which strains to include in the annual flu shot, meaning that the protection is not as robust as it should be.

That said, every bit of protection helps. Medical experts continue to emphasize that even an imperfect vaccine match will cover different groups of viruses.

A preliminary report by the UK Health Security Agency indicates that subclade K includes seven gene changes on the primary segment of the virus. All of these mutations make it more difficult for the body to recognize it as an invader and fight back.

The latest research shows that this year's flu vaccines are offering some level of protection against subclade K viruses. For example, vaccination reduced the odds of an emergency department visit or hospitalization as a result of the flu by nearly 75% in children. The effectiveness dropped to 30% to 40% for adults.

Doctors also caution that the subclade K strain will not be the only strain in circulation. By the end of the season, the dominant strain could be one that is better protected by the current vaccine formulation.

Falling Flu Vaccine Rates in the U.S.

According to recent numbers from IQVIA, retail pharmacies administered about 26.5 million flu shots between August and the end of October. These pharmacies account for about 65% of all vaccines. When compared to the same time period in 2024, there have been more than 2 million fewer flu shots administered.

Flu vaccination rates have also slid in Australia, a part of the world that first experienced the subclade K variant. Flu season in this corner of the globe usually runs from May to July, giving those in the Northern Hemisphere a hint at what is in store. Flu numbers hit a new record in Australia this year, coming in at over 443,000 confirmed cases.

Determining whether a new variant will make a population sicker is not an exact science. However, more cases always translate to more hospitalizations.

Lab testing in the U.S. is also showing an increase in flu cases. This is in line with when cases usually start to trend upward. These numbers are likely to spike heading into the holiday season when indoor gatherings increase.

Lastly, wastewater samples are also indicative of a spread in cases. Because flu is so seasonal, it is easier to spot jumps in cases through these wastewater samples. This varies from COVID-19, a virus that can be detected at any time.

Scientists use wastewater sample data to determine when a state is showing that flu is back in season. The last testing batch shows that Maine, Vermont, Iowa, and Hawaii are the four states with an early onset of the flu.

The takeaway is that now is the time to get your flu shot if you have not already. It is not too late to give your body a better chance heading into the heart of the cold and flu season.

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