How Effective Is the Flu Shot This Year? The Latest Data Shows Surprising Results

Every fall and winter, medical professionals preach the same message: Get your flu shot. While getting the flu shot always makes it less likely to get hit hard by the flu, its efficacy fluctuates. Some years the flu shot offers more protection than other years.

Now that we’re well into flu season (widely considered to be between December and February), you may be wondering just how effective this season’s flu shot is proving to be. Well, the latest data is out—and it may surprise you. Here, infectious disease experts offer up their insight into the data and also give the verdict on if it's too late to get the flu shot this season if you haven’t gotten it already.

Related: Do You Have the Flu? Here's Everything You Need To Know About Navigating Symptoms and Treatment

Why Flu Shot Efficacy Changes Each Year

Similar to how there are different strains of COVID (like Omicron and XEC), there are different strains of the flu. There are four different types of flu viruses: A, B, C and D. Different strains circulate each year. The World Health Organization monitors which strains of the virus circulate all over the world and then recommends which strains should be covered by the annual flu vaccine.

🩺 SIGN UP for tips to stay healthy & fit with the top moves, clean eats, health trends & more delivered right to your inbox twice a week 💊

“Flu vaccine efficacy varies year to year, but it typically ranges between 40 to 60%. Year to year, the effectiveness of flu vaccines depends on the similarity of the vaccine viruses to the circulating virus,” says Dr. Minji Kang, MD, an infectious disease expert at UT Southwestern.

Related: Here's What Flu Symptoms Look Like Day by Day

Dr. Sanjiv Shah, MD, MPH, an infectious disease specialist and the chief medical officer at MetroPlusHealth, says that reports of how effective the flu vaccine is each year are based on comparing people who seek medical care for respiratory illness lasting less than one week and identifying those who test positive for flu with those who test negative and comparing how often each had received that season’s flu shot. “The reports vary from year to year based on which communities are studied, how well the flu strains that circulate match the components in the vaccine and social and underlying health factors of those studied,” he says.

Dr. Shah explains that the flu shot typically contains up to four different inactive strains covering the two main types of flu: A and B. Getting the flu shot, he says, does not mean someone gets the flu. This is because the virus in the vaccine is inactive.

To protect people going into flu season, Dr. Shah says that the composition of the flu vaccine has to be set in place by February to have enough vaccine produced to start giving out doses in the fall. “This requires a scientific crystal ball because the virus can undergo mutations that may allow some strains to escape the vaccine,” he says.

Related: Roll up Your Sleeves! These Are the 10 Best Ways To Prevent the Flu

How Accurate Is the Flu Shot This Season?

With all of this in mind, how accurate is the flu shot this year? Dr. Shah says that data analysis is still very early (flu season is still going on, after all), but in December the CDC reported on data collected since September 2024 to find out how accurate this year’s vaccine is. The result: “56% of one community-obtained virus was similar to one component of the vaccine and 100% of a second flu virus was similar to a different vaccine component,” Dr. Shah says.

This means that, as usual, getting the flu vaccine this year will likely reduce the risk of flu-related illnesses by 40% and reduce the risk of hospitalization by 60%.

Both doctors say that if you haven’t gotten the flu shot yet this season, there is still time. “Rates [of people with the flu] are on the rise now and there is still time to get vaccinated if you have not done so yet to reduce your risk of getting the flu or if you do get the flu, reducing the risk of getting very sick or dying from it,” Dr. Shah says. Dr. Kang adds to this, saying, “Flu shots reduce the severity of the flu for people, prevent hospitalizations and deaths, and reduce the number of people who get the flu.”

If you haven’t gotten the flu yet because you don’t think coming down with the flu is “that bad,” Dr. Kang says to reconsider. “It’s important to note that the CDC estimates that the flu has resulted in between 100,000 and 710,000 hospitalizations and up to 51,000 deaths every year, especially older adults, young children and people who have chronic health conditions. Flu shots protect you and others,” she says. So even if you don’t want to get the flu shot to protect your own health, do it to protect others’.

Dr. Kang also specifies that getting the flu shot doesn’t guarantee you won’t get the flu. But it does mean that if you do get the flu, your symptoms will be less severe and you will recover faster. She also reiterates that you cannot get the flu from the flu shot because the vaccine uses an inactive virus. “Overall, reactions to the flu shot are mild,” she says.

Even though flu shot efficacy fluctuates, both doctors say that it’s absolutely worth getting every year. If you haven’t gotten it yet, book a time to do so today.

Up Next: 

Related: Here's How Long You Can Actually Expect the Flu To Last

Sources

• Dr. Minji Kang, MD, infectious disease expert at UT Southwestern

• Dr. Sanjiv Shah, MD, MPH, infectious disease specialist and the chief medical officer at MetroPlusHealth