Do Higher Flu Rates Mean That the Vaccine Is Less Effective?

The 2025 flu strain has been making headlines since the cold and flu season effectively kicked off, thanks to the new strain of virus that seems to be leading the pack. According to experts, something called subclade K appears to account for the majority of flu cases during this season, and it's absolutely knocking out most of the people who come into contact with it.

That has some people wondering if the flu vaccine is effective this year.

But, according to experts, the reason for the high number of cases may have more to do with something else than the effectiveness of the 2025 vaccinations. And it may be the same thing that caused the 2024/2025 flu season to be such a bad one as well.

Keep reading as we break down what you need to know about this year's flu vaccine, and why some people are saying that this is the worst flu season anyone has seen in more than two decades in the U.S.

According to Good Rx, there were nine different types of flu vaccines available during this year's flu vaccination period, and each of them was trivalent, which means that each shot vaccinated against three different strains of the virus.

Those who are vaccinated with one of the shots that covers the type of flu strain they are exposed to are typically 40 to 60 percent more protected against having to visit a healthcare provider as a result of the flu, which translates into less severe cases.

Now, Good Rx notes that it's next to impossible to know how effective a flu vaccine will be each year, since health professionals don't know ahead of time which strains will be circulating. However, that being said, Johns Hopkins notes that this year's vaccine is just as effective as other years. And while there are some mutations of the subclade K strain that may still be able to infect vaccinated people, the majority of those who received their vaccine this year will have protection.

Doctors are reporting a record number of flu cases this season, according to CNN. In fact, the publication notes that all but four states in the country are reporting "very high" levels of flu activity, with South Dakota and West Virginia saying that they were seeing moderate activity, and Montana and Vermont reporting low activity.

And while they do blame subclade K for being the driver of those cases, it seems like there's another factor driving up the cases and their severity.

According to CNN, vaccination rates have been dropping across the country, and they've noticed a steep decline in rates among children. For example, during the 2019/2020 flu season, vaccination rates reached a high of 53 percent. However, at the same time this flu season, those rates are at just 42 percent. Sadly, those numbers are indicative of another number shared by the publication, the death rate. As of the time of publication, nine children have died of the flu this season.

So how can parents, caregivers, and just about everyone else in the U.S. protect themselves from the virus that has already taken the lives of 5,000 adults this season? Vaccinate. Public health officials at the state levels have been imploring people to get their flu shot as soon as possible in order to protect themselves against what is shaping up to be a rougher than normal season.