When is the best time for a flu shot?

There’s a reason the best time to get the flu vaccine is in the fall. School is starting and we're entering the respiratory season when COVID-19, RSV and flu viruses spread. That means it’s time to get an annual flu shot to protect yourself and others from the flu. 

This is especially important for people at a higher risk for severe illness, such as young children, older adults, pregnant people and those with chronic health problems.

The CDC says everyone 6 months of age and older should get a flu shot every year. It’s the best way to protect yourself and those around you.

It takes time for a flu shot to work — about 2 weeks after you get your shot for antibodies (proteins that prevent infections) in the shot to start to protect you. That’s why the best time to get a flu vaccine is between September and the end of October, before the flu starts to spread in your community. 

The only people who need to get shots earlier are children under age 9 who haven't had a flu shot before. They need 2 shots at least 4 weeks apart.

Pregnant people in their third trimester may get the flu vaccine. This is to protect their babies from getting flu as a newborn when they’re too young to get vaccinated. Babies can start getting flu shots again when they’re 6 months old. 

Flu shot protection isn’t permanent. It usually lasts about 5 or 6 months, which is why you need to get a flu vaccine every year.  Protection also fades over time, so getting vaccinated in early fall (around September or October) helps keep you protected through the peak flu season.

The flu shot has a strong safety record and has been given to millions of children for many years. It’s an important way to protect kids from getting sick and spreading the flu to others. 

Children should get a flu shot every year starting at 6 months old. For the best protection, experts recommend getting vaccinated by the end of October, before the flu starts spreading widely in the community. 

Babies can safely receive a flu shot starting at 6 months old. Babies younger than 6 months can’t get the vaccine, so it’s especially important for caregivers and close contacts to get vaccinated to help protect them.

Children ages 6 months through 8 years need 2 doses the first time they’re vaccinated. The first dose “primes” the immune system. The second dose helps the body build stronger and longer-lasting immunity. Protection may be weaker or not last through the full flu season without the second dose.

A flu shot has been shown to reduce the risk of having to see a doctor for the flu by 40%–60%.

It’s impossible to predict when or if you’ll get the flu, or how your body will react to it. Even usually healthy people can get the flu, and it can be serious. Getting a flu shot is a safer choice than risking an illness.

If you get a flu shot and still get sick with flu, being vaccinated can help make your illness less severe. Even healthy people can get the flu and other illnesses from it. One of the best ways to protect yourself is to get a flu shot.

Flu shots, like other vaccinations such as the COVID-19 shot, are made with an inactive virus or protein. The vaccines are not complete or live viruses and cannot cause illness.

Some people may get a low-grade fever, headache and muscle aches after having a shot. This is your immune system responding to the shot. The immune system is the part of your body that fights illness. This kind of response usually goes away in 1 to 3 days.

It’s more common to have soreness, redness or swelling on your arm where you get the shots. These kinds of responses mean your body is gearing up to fight the virus. If you're later exposed to the flu or COVID-19 virus, you'll be more ready to fight it.

The 2025–2026 flu season was moderately severe for people of all ages. According to the CDC:

• Flu-like illnesses were at high severity 
• Flu hospitalization rates were at moderate severity
• Flu deaths were at moderate severity

Respiratory viruses like the flu spread easily. People who are ill can spread germs that cause respiratory illnesses through droplets when they sneeze, cough or talk. Those droplets can land in your nose, mouth or eyes if you're nearby. 

Plus, a person who is sick can leave infected droplets on objects such as doorknobs. If you touch the doorknob and then touch your nose, mouth or eyes, you might get those germs and become sick.