When Should You Get Your Flu Jab, and Is It Ever Too Late?

Get it too early and the protection may be fading by the time flu peaks. Leave it too late and you may catch flu before the vaccine has had time to work. Timing is one of the most common things people ask us about in autumn, and the advice has shifted in recent years, so here is how to think about it for winter 2026/27.

This page is part of our complete guide to the flu jab in Edinburgh, which also covers who qualifies for a free NHS jab, which vaccine you will get and what to expect afterwards.

The short answer

• Most adults: October to the end of November is the best window.
• Pregnant women: as soon as the vaccine is available, from September, at any stage of pregnancy.
• Children: from September, as early as possible.
• Protection: builds over about two weeks after the jab.
• Missed it? A flu jab in December, January or later can still be worthwhile, and the NHS programme runs until 28 March 2027.

When does flu season peak in the UK?

Flu circulates mostly in winter. In the UK it is not usually significant before the middle of November, it typically peaks in late December, January or February, and most cases fall within an eight to ten week stretch. The timing varies from year to year, though. Last winter, 2025/26, activity peaked in early December. In 2015/16 the peak did not come until late March.

Because nobody can predict the season exactly, the aim is to have protection in place before activity starts climbing and to keep it through the months when flu is most likely.

Why adults are now vaccinated from October, not September

Not long ago, flu vaccination for adults started in early September. That has changed because of evidence that protection in adults fades within the season. Studies show better protection between 14 and 90 days after vaccination than after 91 days or more, and the drop is more noticeable in older adults.

On that basis the Joint Committee on Vaccination and Immunisation (JCVI) advised moving the start of the adult programme to the beginning of October, on the understanding that most people would be vaccinated by the end of November. That gives the best protection over the usual December and January peak. Children are different: protection from the nasal spray does not appear to wane in the same way, and flu tends to spread among children first, so their programme starts in September.

How long does the flu jab take to work?

Protective immune responses usually develop within about 14 days of vaccination. Until then you can still catch flu, so if you have something coming up, such as a family gathering, a hospital appointment for someone close to you, or a long-haul flight, aim to be vaccinated at least two weeks beforehand.

This also explains a common story: someone has a flu jab, catches a heavy cold or flu a few days later, and blames the vaccine. The injected vaccine cannot cause flu. More often they caught something that was already going round, before protection had built up.

The NHS timetable in Scotland for 2026/27

The Scottish Government has set out the following dates for this winter:

• Early September: children's flu programme and the offer to pregnant women begin.
• Late September: flu vaccination begins for adults who are only eligible for flu.
• 5 October: flu and Covid-19 vaccines start being given together to eligible adults.
• 6 December: the aim is for every eligible adult to have been offered both vaccines.
• 31 January 2027: the winter Covid-19 programme ends.
• 28 March 2027: the flu programme ends.

In Edinburgh, NHS Lothian sends invitations by text, email or letter. If you are eligible but have not heard anything, you can book through the NHS inform portal or call the National Vaccination Helpline on 0800 030 8013. Our page on who gets a free flu jab in Scotland explains the eligible groups.

Is it too late to get a flu jab in December or January?

Usually not. A late season, or a second wave of a different strain, can keep flu circulating into February and March, and protection starts building within a couple of weeks of the jab. The NHS keeps offering flu vaccination until the end of March for exactly that reason.

The earlier window is still better, because it covers the most likely peak. But if you have missed it, a December or January jab is more useful than going without. If you are not eligible on the NHS, private flu vaccination can also be arranged later in the season, subject to the pharmacy still having vaccine.

Timing in pregnancy

Pregnant women are the main exception to the October rule. The advice is to have the injected vaccine as soon as it is available, at any stage of pregnancy. Flu is more likely to cause serious illness in pregnancy, and vaccination also passes protection to the baby for its first months of life, when babies are too young to be vaccinated themselves.

If you are also due an RSV vaccine in pregnancy, the two can be given at the same appointment once you reach 28 weeks. Flu vaccination should not be held back to wait for that point, though, if it means going unprotected through the autumn.

Timing around other vaccines

For most vaccines, timing is simple. A flu vaccine can be given at the same appointment as a Covid-19 vaccine, and at the same time as a shingles vaccine. If they are not given together, any interval between them is fine.

For older adults having an RSV vaccine, guidance is not to routinely give it on the same day as a flu vaccine, because the immune response to each may be slightly reduced. No set gap is needed, so they can be a day or more apart. Edinburgh Vaccination Clinic, which operates from the same pharmacy, explains combining flu with Covid and other vaccines in more detail.

Timing around travel

Flu seasons run at different times around the world. In the southern hemisphere, in places such as Australia, South Africa and much of South America, flu season usually falls during the UK summer, and in the tropics flu can circulate all year. If you are travelling, especially on a cruise or with a large group, it is worth mentioning flu when you discuss travel vaccines, because the vaccine you had last winter may not cover what is circulating where you are going.

For winter travel within the northern hemisphere, the usual autumn advice applies. Allow two weeks for protection to build before you go. Our travel clinic can help you plan around other travel vaccines.

What if you are unwell on the day?

A minor illness without a temperature, such as a mild cold, is not a reason to postpone your flu jab. If you have a fever or feel acutely unwell, it is better to wait until you have recovered, mainly so that the symptoms of your illness are not confused with a reaction to the vaccine. Once you are well again, rebook rather than waiting for next year.

Do you need a flu jab every year?

Yes. Flu viruses change from season to season, the vaccine is updated each year to match, and protection from last year's vaccine is likely to be low by now. The advice in the national guidance is annual vaccination for everyone in an eligible group, and the same logic applies if you are vaccinated privately.

Frequently asked questions about flu jab timing

Is September too early for a flu jab?

For most adults, October is better, because protection is strongest in the first three months and flu usually peaks from December. The exceptions are pregnant women and children, who are advised to be vaccinated as early as possible from September.

I missed my NHS flu appointment. Can I still be vaccinated?

Yes. You can rebook through the vaccination booking portal on NHS inform or by calling 0800 030 8013. The NHS flu programme in Scotland runs until 28 March 2027.

I have just had Covid. When can I have my flu jab?

Once you have recovered. Having been ill is not a reason to avoid the vaccine, but if you still have a fever or feel acutely unwell, wait until you are better before being vaccinated.

I have already had flu this winter. Should I still have the jab?

Usually, yes, once you have recovered. The vaccine covers three strains, and a flu-like illness may well have been a different virus. Ask a pharmacist if you are unsure.

How long does protection from the flu jab last?

It is designed to cover the current season. Protection is strongest in the first few months and fades over time, which is why a new vaccine is needed every year.

When is the best time to be vaccinated if I am over 65?

October or November, so that protection is at its strongest over the usual December to February peak. If you are eligible, NHS Lothian will invite you, and the aim is for everyone eligible to have been offered a vaccine by 6 December.

Related reading

• Flu Jab in Edinburgh: The Complete 2026/27 Guide from Bruntsfield Pharmacy
• Who Gets a Free Flu Jab in Scotland This Winter, and What If You Don't Qualify?
• Private Flu Jab in Edinburgh: What Happens at Your Appointment

For the full picture, including side effects and which vaccine you will be given, see our complete guide to the flu jab in Edinburgh.

Reviewed by Ather Diab, Superintendent Pharmacist and Independent Prescriber (GPhC 2233707). Bruntsfield Pharmacy, GPhC registration 1042628, 129 Bruntsfield Place, Edinburgh EH10 4EQ. Last reviewed: 14 October 2026.

This page is for general information and does not replace individual advice. Flu vaccines are prescription-only medicines. In an emergency, call 999.

Sources: UKHSA Green Book, chapter 19, Influenza, 25 August 2026; Scottish Government, SGHD/CMO(2026)05, 23 March 2026, and SGHD/CMO(2026)18, 21 September 2026; NHS inform, flu vaccine and winter vaccines; NHS Lothian, adult flu vaccination.