September and October Are the Best Months for a Flu Shot
The Centers for Disease Control and Prevention recommends that everyone 6 months and older get a flu vaccine every year, including for the 2026-27 flu season. With rare exceptions, everyone is eligible regardless of age or health status, according to the CDC.
There are two reasons an annual shot is needed. The flu virus constantly changes, so the vaccine’s composition is reformulated each year, and the immune protection gained from vaccination weakens over time.
September and October are the most appropriate times to get vaccinated, the CDC advises. Ideally, vaccination should be completed by the end of October, because it takes about two weeks after vaccination for antibodies to form in the body.
Getting vaccinated early, in July or August, is not recommended in most cases. A shot given too early can lose protective effect as the season wears on. Children who need two doses, however, can start earlier for scheduling reasons.
Even if the recommended window is missed, a later vaccination still helps. Flu usually rages most between December and February and can continue into May. The CDC recommends continuing vaccination throughout the season as long as flu viruses are circulating.
Vaccination is especially important for groups at high risk of complications. According to the CDC, the high-risk groups include adults 65 and older, children under 5, pregnant women, and people with chronic conditions such as asthma, diabetes and heart disease. The risk is particularly great for children under 2, the CDC said.
All flu vaccines supplied in the United States this season are trivalent vaccines, containing three virus components. They include two influenza A viruses and one influenza B virus of the Victoria lineage, and all three components have changed from last season. A Food and Drug Administration advisory committee recommended the composition in March.
For people 65 and older, products designed to induce a stronger immune response, such as high-dose vaccines or vaccines containing an adjuvant, are preferentially recommended. This year, an mRNA flu vaccine for adults 50 and older was also newly approved, widening the options.
Children from 6 months to 8 years old who are receiving a flu vaccine for the first time may need two doses. The two doses should be spaced at least four weeks apart, the CDC advises.
The flu vaccine can be given on the same day as the COVID-19 vaccine and the respiratory syncytial virus, or RSV, vaccine. The CDC says that when a person is eligible for several vaccines, they can be administered together in a single visit, and if given separately, there is no minimum waiting period. The CDC’s clinical guidance for the COVID-19 vaccine this season lists adults 18 and older as eligible.
The RSV vaccine’s eligibility is narrower than the flu vaccine’s. The CDC recommends vaccination for all adults 75 and older, and also for adults ages 50 to 74 at high risk of severe RSV. The RSV vaccine is not an annual shot and is currently given as a single dose.
For those who are pregnant, there is a separate RSV vaccination schedule to protect the baby. The CDC recommends one dose between weeks 32 and 36 of pregnancy, from September through January in most parts of the United States.
Vaccination sites include pharmacies, medical offices and local health departments. Most health insurance plans cover flu shots received at in-network pharmacies or medical offices at no cost to the insured. People without insurance can be vaccinated free or at low cost at local health departments or community health centers. Costs and coverage can vary by insurance plan and vaccination site, so it is best to check before visiting.
