When should you get your flu shot? Timing tips to maximize protection
Medically reviewed by Dr. Betsy Koickel, MD on September 14, 2026.
Key takeaways
- The best time to get a flu shot is in September or October, before the flu season officially begins.
- It is not necessarily too late to get a flu shot later in the season, especially if the flu is still spreading.
- Pregnant women should talk with a healthcare provider about the best timing for a flu shot.
Before we know it, the days are getting cooler, and flu season is here. Since flu season can ramp up quickly once the flu starts spreading, this makes timing your flu shot important.
Getting vaccinated at the right time gives your body time to build protection before flu activity is widespread, while also helping the protection last through the months when flu is most likely to circulate.
The best time of year to get vaccinated
If you are wondering when to get a flu shot, the best window for most people is September or October. The Centers for Disease Control and Prevention recommends that most people get vaccinated by the end of October to help build protection before flu activity begins.
An important thing to understand is that the flu shot does not work right away. It takes about two weeks to develop enough antibodies to protect against the flu. Getting vaccinated in early fall gives your immune system time to respond before you are most likely to be exposed to the flu.
When do flu shots come out? Flu vaccines often become available in late summer or early fall, depending on the location, vaccine supply, and the specific flu season. However, just because flu shots are available does not always mean getting them early is ideal.
Getting vaccinated too early can work against you because protection from the shot may decrease over time. For most adults, especially those 65 and older, July or August is generally too early. The goal is to time the vaccine so protection is strong when flu activity is at its peak.
That said, sometimes earlier vaccination is recommended. For example, children who need two doses of the flu vaccine may want to receive the first dose as soon as it is available because the second dose must be given at least four weeks later. A healthcare provider can help determine the right timing based on age, health history, and vaccine availability.
Is it ever too late to get a flu shot?
Another common question is, when is it too late to get a flu shot? Often, it is not too late as long as flu viruses are still circulating. While getting vaccinated by the end of October is ideal, a later flu shot can still offer protection during the remaining months of flu season.
Flu activity often peaks between December and February, but it can continue into spring. If you missed the fall window, getting vaccinated later may still help lower your risk of illness, severe symptoms, or days of missed work or school.
Special timing considerations for pregnant women
There are a few special considerations for a flu shot when pregnant. Pregnancy increases the risk of serious flu-related complications, and vaccination can help protect the mother and the baby after birth.
For many pregnant women, September or October is still a good time to get vaccinated. However, vaccination in July or August may be recommended for those in the third trimester because it can help protect the baby during the first few months of life, before the infant is old enough to receive a flu vaccine of their own.
Pregnant women should receive the flu shot, not the nasal spray flu vaccine. Anyone who is pregnant and unsure about timing should talk with an OB-GYN, primary care provider, or urgent care provider for personalized recommendations.
Flu shots are available at the urgent care centers during flu season. To get started, find a center near you and walk in or save your spot online. Getting vaccinated at the right time can help you enter flu season with stronger protection.
FAQs
Here are frequently asked questions about when to get a flu shot.
How long does it take for a flu shot to become effective?
It takes about two weeks after a flu shot for protective antibodies to develop. Getting vaccinated before flu activity is widespread gives your body time to build protection before the season truly begins.
Can you get a flu shot if you're currently sick?
If you have a mild illness, such as a cold without a fever, you may still be able to get a flu shot. If you have a moderate or severe illness, it may be better to wait until you feel better. A healthcare provider can help you decide based on your symptoms.
When not to get a flu shot?
People should not get a flu shot if they are younger than 6 months old or have had a severe, life-threatening allergic reaction to a flu vaccine or ingredient. Speak to your healthcare provider for personalized recommendations.
References:
