Flu vaccines are offered every autumn and winter, and health agencies in both the UK and the US say it is not too late to have one in November. This page summarises current guidance from the NHS and the US Centers for Disease Control and Prevention (CDC) on flu vaccine timing: when to get the flu vaccine, who it is offered to and what to expect. It is general information, not personal medical advice. If you are unsure whether the vaccine is right for you, ask a pharmacist, GP or other clinician.
When to get the flu vaccine
The NHS says the flu vaccine is offered every year in autumn or winter and advises having it as early as you can. For the current season, the last date to have the free NHS vaccine is 31 March 2027, and online booking closes on 30 March 2027. The NHS adds that it can take up to 14 days for the vaccine to start working.
In the US, the CDC’s 2026-2027 guidance (page dated September 1, 2026) says most people who need one dose should ideally be vaccinated in September or October. It says vaccination should continue after October and throughout the season for as long as flu viruses are circulating and unexpired vaccine is available. So if you have not yet had a shot, November is still a sensible time to ask about one.
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The CDC’s key facts page notes that antibodies develop about two weeks after vaccination, which is why it recommends vaccinating before flu spreads widely in your community.
Why very early vaccination is not advised for everyone
The CDC says that for most groups, vaccination in July or August is not recommended because protection can fade before the season ends. This applies particularly to adults aged 65 and older, and to people in the first or second trimester of pregnancy, who should preferably wait until September or October. There are exceptions: pregnant people in the third trimester may be vaccinated earlier to help protect their babies after birth, and children who need only one dose can be vaccinated in July or August.
Children aged 6 months through 8 years who need two doses should have the first as soon as vaccine is available, with the second at least four weeks later, ideally by the end of October.
Who is offered it
In the UK, the NHS lists the following adults as eligible for a free flu vaccine:
- people aged 65 or over, including anyone who turns 65 by 31 March 2027
- adults aged 18 to 64 with certain long-term conditions, such as asthma, COPD, heart conditions, diabetes or a weakened immune system
- pregnant people, at any stage of pregnancy
- care home residents, and the main carers of an older or disabled person
- people who live with someone who has a weakened immune system
- people aged 16 or over who are rough sleeping or staying in a homeless hostel or night shelter
- frontline health and social care workers, who usually get it through their employer
Children are covered on a separate NHS page. You can book through the NHS App or online, find a pharmacy offering free vaccination, or contact your GP surgery.
In the US, the CDC says everyone aged 6 months and older, with rare exceptions, should get a flu vaccine every season, with a particular priority on people at higher risk of serious complications.
What the vaccine is like
- It cannot give you flu. The NHS says the injected vaccines used in the UK contain no live flu viruses. The CDC says flu shots contain inactivated viruses or only viral proteins. You can still catch flu after vaccination, but the NHS says it is likely to be milder and shorter.
- Common side effects are mild and usually clear in one to two days, according to the NHS: a sore arm, a slightly raised temperature and an aching body. The CDC also lists headache, nausea and fatigue.
- Serious allergic reactions are very rare, per both agencies. The NHS says anyone who has had a serious allergic reaction to a previous dose or an ingredient should not have it again.
- If you have a high temperature, the NHS advises waiting until you feel better.
- Pregnancy and breastfeeding: the NHS says studies show it is safe at any stage of pregnancy and can be given while breastfeeding.
Which type you will be offered
In the US, the CDC says people aged 65 and older have three preferred options, Fluzone High-Dose, Flublok and Fluad, and that any other age-appropriate vaccine should be used if none of those is available. A nasal spray is approved for ages 2 through 49 but is not recommended for pregnant people, people with weakened immune systems or people with certain medical conditions. In the UK, the NHS lists a nasal spray only for 16- and 17-year-olds among its adult pages. Which product you receive depends on your age, health and where you are vaccinated.
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Colder months bring other health questions too. See our guides to vitamin D in autumn and winter and to whether to exercise with a cold.
When to ask a clinician
Talk to a pharmacist or doctor before vaccination if you have had a serious allergic reaction to a flu vaccine or its ingredients, if you are pregnant, or if you have a long-term condition and are unsure which vaccine suits you. Seek medical help if you feel unwell after a vaccine in a way that worries you.
Sources
- NHS: Flu vaccine
- CDC: Interim Clinical Considerations for the Use of Seasonal Influenza Vaccines, 2026-2027 (timing of vaccination)
- CDC: Key Facts About Seasonal Flu Vaccine
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