Most of us only think about the flu shot once someone around us gets sick. By then, you’re already playing catch-up. In fact, seasonal influenza causes an estimated 3 to 5 million severe cases and up to 650,000 deaths worldwide each year, highlighting why prevention matters [4].
Knowing when to get the flu shot, instead of just getting one whenever you remember, makes a real difference to how well it protects you. Here’s the thing: timing isn’t the same for everyone. It depends on where you live and how quickly your body builds immunity. This guide breaks down exactly when to get the flu shot, so you’re covered before flu season hits your city, not after.
What Is Influenza and What Does It Look Like?
Flu, also known as seasonal influenza, is a contagious respiratory illness caused by influenza viruses. There are two main types you need to know about.
Type A is the unpredictable one, since it lives in both humans and animals and drives most major flu seasons and pandemics. Type B sticks to humans only and tends to be milder.
It spreads through the air when an infected person coughs, sneezes, or talks. The virus settles into the respiratory tract and multiplies fast, and it can even survive a few hours on surfaces like doorknobs, which is exactly why regular hand washing matters.
Symptoms usually show up 1 to 4 days after exposure. This is called the incubation period, and you can spread the virus to others a day before you even feel sick yourself [1].
Common symptoms include:
- Sudden fever and chills
- Cough and sore throat
- Runny or blocked nose
- Body aches and headache
- Extreme fatigue
- Vomiting or diarrhea (more common in children)
Most healthy adults recover within a week. That said, the flu can hit harder for the elderly, pregnant women, and people with chronic conditions.
Who Needs the Flu Vaccine?
Almost everyone over 6 months of age should get the vaccine. However, the Ministry of Health and Family Welfare in India has prioritized flu vaccination for the following high-risk groups [2] [7]
High priority group:
- Elderly individuals (≥65 years of age)
- Children (aged 6 months to 8 years)
- Pregnant women
- Health care workers
- People with chronic health conditions like asthma, diabetes, cancer, heart, liver, kidney, or blood disorders
- Those who are immunocompromised
Individuals who should avoid:
- Any child who has had a serious allergic reaction to a flu shot before or who is severely allergic to any part of the vaccine that could kill them.
- Anyone with Guillain Barré Syndrome, a disorder of the nervous system.
- Children with severe egg allergy should receive the immunisation in a location with facilities for treating emergencies.
- If your child has a moderate egg allergy (just rashes), the vaccine can be delivered, following which the child should remain in the clinic for 30 minutes after vaccination.
What is the Ideal Time to Recieve Flu Vaccine in India?
The best time to get a flu shot is about 2 to 4 weeks before flu activity typically rises in your region, giving your body enough time to build protective antibodies. In India, flu season varies by geography, with some areas seeing peaks during the monsoon and others during winter. Getting vaccinated too early may lead to reduced protection later in the season, particularly in older adults. Since timing can influence how well the vaccine works, it’s important to plan your vaccination around your local flu season.
When is the best Time to get a Flu Shot?
This is the part most people skip past, but it’s where the real decision-making happens. The right timing isn’t one-size-fits-all. It depends on your age, whether you’re pregnant, and whether you’ve had a flu shot before[3][4].
For Most Adults: Aim for Vaccination Before Flu Season Peaks
For most people needing just one dose a year, the shot is ideally given during September or October if you’re in a winter-peak region, or a few weeks ahead of your local flu season if you’re in a monsoon-driven part of India.
Keep in mind:
- The ideal timing varies depending on your local flu season.
- Vaccination can continue throughout the flu season as long as flu viruses are circulating.
- Missing the ideal window does not mean you should skip vaccination altogether.
Older Adults and Early Pregnancy: Avoid Vaccinating Too Early
If you’re an adult, particularly aged 65 or older, or if you’re in your first or second trimester of pregnancy, it’s generally best to avoid getting vaccinated too early in the year unless you may miss the opportunity later.
This is because:
- Protection from the vaccine can gradually decline over time.
- Older adults may experience faster waning of immunity.
- Vaccinating closer to the period of peak flu activity may offer better protection.
Pregnancy: Timing Matters
If you’re pregnant and in your third trimester, earlier vaccination works in your favor. Studies show it lowers the risk of flu illness in your baby during their first few months of life, when they’re still too young to be vaccinated themselves.
If you’re earlier in pregnancy, though, it’s generally better to wait a little closer to flu season rather than vaccinating too far ahead, unless there’s a real chance you won’t be able to get vaccinated later.
Children Who Need Two Doses
Children aged 6 months to 8 years receiving the influenza vaccine for the first time may require two doses.
For these children:
- Give the first dose as early as possible.
- The second dose should be administered at least four weeks later.
- Completing both doses before flu activity peaks provides the best protection.
- Children who require only one dose can get vaccinated earlier, often during routine healthcare visits.
If you’re unsure whether your child needs one dose or two, read our guide to understand the recommended timing by age and vaccination history: When Should Your Child Get the Flu Vaccine?
| Missed Your Flu Vaccine?
It’s never too late to get vaccinated. However, if you missed your flu shot last year or any year before that, now’s a good time to catch up with the latest available vaccine. Flu viruses mutate every year, so each new vaccine fights the strains currently circulating. |
Which Flu Vaccines are Available?
Influenza vaccines are available in two forms:
- Inactivated influenza vaccine (injection): Suitable for most age groups.
- Live attenuated influenza vaccine (nasal spray): Recommended for healthy, non-pregnant individuals aged 2 to 49 years.
How Often Do You Need a Flu Shot?
The short answer: once a year, every year. Here’s why that matters:
- Influenza viruses change frequently, so last year’s vaccine may not match this year’s strains.
- Immunity from a previous vaccination naturally fades over time.
FAQs
How long does it take for the flu shot to start working?
About two weeks. Your body needs that time to build up enough antibodies to protect you against the flu.
Can I get the flu shot if I’m already feeling a bit under the weather?
A mild cold or low fever usually isn’t a reason to wait. However, if you have a high fever or a moderate to severe infection, it’s better to wait until you’ve recovered.
Does the flu shot protect against all types of flu?
No. It targets the specific strains expected to circulate that season, based on global surveillance data, so it won’t cover every possible flu variant.
Can pregnant women get the flu shot?
Yes, and it’s actually recommended in any trimester. It protects the mother and passes some protection to the baby, who can’t get vaccinated until 6 months of age.
Is it normal to feel slightly unwell after the flu shot?
Yes. A sore arm, mild fatigue, or a low-grade fever for a day or two just means your immune system is responding, not that you’ve caught the flu.
Can I get the flu shot along with other vaccines?
Yes, in most cases. Doctors may use different injection sites to reduce soreness, but there’s usually no need to space them apart.
Can I get the flu vaccine at the same time as other vaccines?
Yes, in most cases, including for kids getting other routine childhood immunizations. Doctors may use different injection sites to reduce soreness, but there’s usually no medical reason to space the shots apart.
What happens if I get the flu despite getting vaccinated?
You can still get infected, but vaccinated people typically experience milder symptoms and a lower risk of hospitalization compared to those who skipped the shot.
Is the flu shot safe for people with egg allergies?
Most flu vaccines are egg-based, so people with severe egg allergies should talk to their doctor first. Egg-free alternatives are available in many cases.
References:
1. Centers for Disease Control and Prevention. Influenza [Internet]. In: CDC Yellow Book 2026: Health information for international travel. Atlanta (GA): CDC; [cited 2026 Jun 23]. Available from: https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/influenza.html
2. Centers for Disease Control and Prevention. Who should and who should not get a flu vaccine [Internet]. Atlanta (GA): CDC; [cited 2026 Jun 23]. Available from: https://www.cdc.gov/flu/vaccines/vaccinations.html
3. Centers for Disease Control and Prevention. Seasonal influenza vaccine dosage and administration [Internet]. Atlanta (GA): CDC; [cited 2026 Jun 23]. Available from: https://www.cdc.gov/flu/hcp/vax-summary/vaccine-dosage-admin.html
4. Centers for Disease Control and Prevention. ACIP recommendations summary: influenza (flu) [Internet]. Atlanta (GA): CDC; [cited 2026 Jun 23]. Available from: https://www.cdc.gov/flu/hcp/vax-summary/acip-recommendations.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fflu%2Fhcp%2Facip%2Findex.html
5. World Health Organization. Vaccines against influenza: WHO position paper [Internet]. Geneva: World Health Organization; [cited 2026 Jun 23]. Available from: https://iris.who.int/server/api/core/bitstreams/1a67eb7c-3a17-451a-866d-f0c3e4be2dc9/content
6. Indian Academy of Pediatrics. Influenza (flu) vaccines [Internet]. Mumbai: Indian Academy of Pediatrics; [cited 2026 Jun 23]. Available from: https://iapindia.org/pdf/vaccine-information/INFLUENZA-FLU-VACCINES.pdf
7. Dhar R, Ghoshal AG, Guleria R, Sharma S, Kulkarni T,Clinical practice guidelines 2019: Indian consensus-based recommendations on influenza vaccination in adults. Lung India. 2020 Aug;37(Supplement):S4-S18, Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC7703812/
(The article is written by Nancy Dixit, Associate Manager, Clinical Health & Content, Medical Affairs, and reviewed by Monalisa Deka, Deputy Manager, Clinical Health & Content, Medical Affairs)
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