The flu is making people sick across the United States this season, driven largely by the spread of a new strain known as subclade K. As cases climb nationwide, infectious disease specialists are urging anyone who has not yet been vaccinated to get a flu shot as soon as possible.

Still, many people remain uncertain. Some wonder whether it is too late for the vaccine to help, while others question whether getting vaccinated could be riskier than catching the flu itself. According to scientists, the vaccine does help — and the flu poses a far greater risk. However, widespread misinformation about vaccines has made it increasingly difficult for people to separate fact from fiction.

Here are some common myths about the flu shot — and what scientific evidence actually shows.

Myth: The flu shot doesn’t work

The reality is that flu vaccination significantly reduces the risk of severe illness, hospitalization and death.

Earlier this week, Jim O’Neill, acting director of the US Centers for Disease Control and Prevention, noted in a social media post that a federal review found no randomized controlled trials proving that pediatric flu vaccines reduce community transmission, hospitalizations or deaths in children.

While that statement is technically correct, experts say it is misleading. Randomized controlled trials are not well suited to measuring rare but serious outcomes such as hospitalization or death.

“Most randomized trials simply don’t include enough participants to reliably detect differences in severe outcomes,” said Dr. Mark Loeb, a flu researcher at McMaster University in Ontario.

Instead, scientists rely on large observational studies designed to assess real-world effectiveness. In October, Loeb published a major meta-analysis in the journal Clinical Microbiology and Infection that examined 165 observational studies involving more than 600,000 people.

Many of these studies used a “test-negative” design, which compares vaccination rates between people who seek care for flu-like symptoms and test positive for influenza and those who test negative. This approach helps reduce bias by ensuring that both groups had similar reasons for seeking medical care.

The findings were clear: flu vaccines consistently protect against severe complications across all age groups, even when the vaccine does not perfectly match circulating strains.

On average, vaccination cut the risk of hospitalization or intensive care admission in children by about 50% and reduced pneumonia risk by 70%. Adults under 65 saw roughly a 40% reduction in the risk of hospitalization or pneumonia. Among adults over 65, vaccination lowered hospitalization risk by about 30%, pneumonia risk by 45%, and intensive care admissions by more than half.

“This is a particularly important year to get vaccinated, given the severity of the virus circulating,” Loeb said. “Our analysis provides strong evidence of the benefits.”

Myth: There’s no point in getting a flu shot because it doesn’t match the new strain

The reality is that this season’s vaccine is still providing meaningful protection.

While subclade K is not specifically included in this year’s flu shots, early evidence suggests the mismatch has not significantly undermined vaccine effectiveness. Subclade K belongs to the influenza A family and is classified as an H3N2 strain.

H3N2 viruses are known for mutating rapidly, often complicating scientists’ efforts to select strains for annual vaccines. That challenge emerged this year after vaccine formulations were finalized and H3N2 strains began spreading widely in the Southern Hemisphere, fueling a severe flu season in Australia.

Because seasons dominated by H3N2 viruses are often associated with more severe illness, questions about vaccine performance have taken on added urgency. So far, experts say existing vaccines are still reducing the risk of serious outcomes, even if protection against infection itself is not perfect.