4 ways to protect against the “super flu”

A new so-called “super flu” is causing a surge in cases and hospitalizations across the United States as well as other parts of the world. The new variant known as subclade K is a mutated form of the influenza A strain H3N2, which is generally considered to be more severe, particularly among older people.

In the U.S. there have been at least 11 million infections and 120,000 flu-related hospitalizations as of December 27, according to the Centers for Disease Control and Prevention (CDC). So far this season, 5,000 people have died from the flu, including nine children. And flu activity is expected to continue for several more weeks.

Subclade K has been dubbed ”super flu” because of how quickly it has spread but there is no evidence that it’s more severe than related H3N2 variants.

There are some proven ways to reduce your risk of getting, or spreading, the flu. Take the following four steps to protect yourself, your friends and relatives, and your community:

1. If you haven’t done so already, get a flu shot. It is not too late. Everyone ages 6 months and older should be vaccinated against the flu.
2. Stay home if you are sick.
3. Wash your hands well and often with soap and water.
4. Avoid touching your eyes, nose, and mouth with unwashed hands.

In the U.S., about 130 million doses of the flu vaccine have already been doled out this season. This year’s shot may not be a perfect match against subclade K and may not prevent infection entirely, but it can still help reduce the severity of the infection and lower the risk of serious flu-related complications, including death.

Here’s what you need to know about the flu vaccine and why flu prevention is so essential—even for otherwise young, healthy people

The flu can be dangerous—even deadly

During the 2024-2025 flu season, at least 43 million people in the United States got the flu, according to the end of season estimates from the Centers for Disease Control and Prevention (CDC) Of these people, at least 560,000 were hospitalized, and 38,000 died. But the number of flu cases could be as high as 73 million and the death toll from the latest flu season may be as high as 99 thousand people, the CDC reports.

And the flu shot prevented those numbers from climbing even higher. The CDC also estimates the flu shot prevented at least 9.4 million infections, at least 170,000 flu-related hospitalizations, and up to 39,000 deaths during the 2024-2025 season.

But many people still think of the flu as a bad cold. This is not true.

Flu symptoms may seem like just a cold, but they’re usually more intense and linger longer. The stress the flu puts on the body can also lead to more serious complications, including pneumonia, inflammation of the heart, or stroke. People with other health issues, such as diabetes, heart disease, and lung disease are among those at greatest risk. Older people, pregnant people, and children are also at higher risk for flu-related complications.

Preventing the spread of the flu can not only keep you healthy but also protect the vulnerable people around you.

Vaccinations are not just about one person. They help protect schools, communities, cities—even countries as a whole. When everyone who is eligible for a vaccine gets immunized, they provide a shield of protection for those who are not eligible. That shield of protection is called herd immunity. This happens when a virus or pathogen stops spreading because enough people are immune to it.

The best way to protect yourself and others who are more vulnerable: Get a flu shot.

What is the flu vaccine?

The precise formulations of the vaccine change every year, but the basic foundations of the vaccine remain constant. The shots are either made with flu viruses that have been inactivated, which means they’re not infectious, or they’re made without viruses at all (recombinant flu vaccines). This means that you can’t get the flu from any type of shot.

Depending on the year, both three-component (trivalent) or four-component (quadrivalent) vaccines may be available. Three-component vaccines defend against three types of flu virus: an influenza A (H1N1), another influenza A (H3N2), and an influenza B virus. The four-component vaccines protect against these same viruses, plus an additional B virus.

For the 2024-2025 flu season, the flu shot was trivalent—not quadrivalent. It offered protection against two A strains (an H1N1 and an H3N2), and one B strain (Victoria). That was because the additional B strain (Yamagata) has not been circulating in recent years. The same will be true this flu season. All U.S. flu shots are trivalent vaccines.

Certain vaccines are licensed for use in specific age groups, such as children and people older than 65. Some groups of people are also not candidates for certain vaccines. Your healthcare provider (HCP) will recommend what is safe and appropriate for you, depending on your age, the health of your immune system, allergies, and other factors. For adults older than 65, higher-dose vaccines may be recommended since they are potentially more effective for people who have weakened immune systems than regular dose flu vaccines.

How is the flu vaccine selected?

Because the flu virus is constantly changing, researchers reevaluate the strains expected to be in circulation or spreading in communities each year. The exact components of the vaccine, therefore, may change from year to year. The World Health Organization (WHO) assembles a board of researchers from their own collaborating centers and other key laboratories—including the CDC and the Francis Crick Institute—to determine:

• Which viruses are making people sick
• How fast the viruses are spreading
• The effectiveness of the previous vaccine

Once this information has been presented and reviewed—usually in February of each year—the FDA makes the official vaccine decision for the United States. After that, manufacturing companies begin creating the vaccine, a process that usually takes about six months. Ideally, people in the U.S. should get their annual flu shot by the end of October.

In seasons when the vaccine is well-matched to most circulating influenza viruses, getting a flu shot may decrease the risk of needing medical care for the flu by 40 percent to 60 percent.

Who needs the shot?

The CDC recommends that everyone ages 6-months and older get the flu vaccine.

The more people who are vaccinated, the fewer chances the virus has to spread. But vaccination is particularly important for people who are at higher risk for severe flu and flu-related complications. This includes:

• Children younger than 5
• Adults older than 65
• People with chronic health issues or a weakened immune system
• Residents of nursing homes or other care facilities

Pregnant people should also get the flu shot during and after pregnancy. It can greatly reduce the risk of complications and protect infants from illness for several months after birth. Babies younger than 6-months old are too young to be vaccinated but can still receive flu antibodies in the uterus, or before birth.

​There are some rare exceptions to the flu vaccine recommendations. People younger than 6-months old should not receive the flu vaccine. Some people with a history of Guillain-Barré Syndrome (GBS) should also not get a flu shot. (Guillain-Barré is a rare disorder in which your immune system attacks nerve cells causing muscle weakness and sometimes paralysis. Most people recover.) Those who have ever had GBS should talk to their healthcare provider (HCP) to determine if the flu vaccine is right for them.

The flu shot is also not recommended for those who’ve had severe allergic reactions to it in the past, or people who are allergic to certain vaccine components like gelatin or some antibiotics.

Egg allergies may be an exception. Many flu vaccines are made using egg-based technologies, but most people with egg allergies can still receive the flu vaccine without needing to be observed for an allergic reaction. In fact, the CDC says those with egg allergy may receive “any vaccine (egg-based or non-egg-based) that is otherwise appropriate for their age and health status.” People who are concerned about a severe egg allergy should discuss their options with their HCP.

Timing the flu shot

People should get their flu shot before the virus starts to spread each year. In the U.S. flu usually beings to circulate in October and peaks between December and February. But people can still get the flu as late as May.

The CDC recommends getting vaccinated by the end of October. Because children ages 6 months to 8 years who are getting vaccinated for the first time need two doses four weeks apart, it’s a good idea to begin their vaccination process even earlier.

And remember it takes two weeks to develop protective antibodies following immunization. This means that after you get a flu shot, it may take about two weeks for your body to gain protection against the flu. During that time, consider taking precautions against infections like the flu. This includes washing your hands well and often with soap and water and avoiding close contact with people who are sick, especially if you are at higher risk for flu-related complications.