What is influenza (the flu)?

Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to hospitalization or even death.

How does the flu spread?

The flu spreads mainly through droplets made when people with the flu cough, sneeze, or talk. These droplets can land in the mouths or noses of people who are nearby. Less often, a person might get the flu by touching a surface or object that has the flu virus on it and then touching their own mouth, nose, or eyes.

What are the symptoms of the flu?

Common symptoms include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, and fatigue. Some people may also have vomiting and diarrhoea, though this is more common in children than adults.

How can the flu be prevented?

The best way to prevent the flu is by getting vaccinated each year. Other preventive measures include washing your hands often, avoiding close contact with sick people, and covering your mouth and nose with a tissue or your elbow when you cough or sneeze.

Can I get the flu from the vaccine?

No, the flu vaccine contains an inactivated virus or proteins that cannot cause infection. It helps your immune system recognize and fight the virus effectively.

How can I protect myself from the flu?

The best way to prevent the flu is to get vaccinated annually. Additionally. practice good hygiene: wash hands frequently, avoid close contact with sick individuals, and maintain a healthy lifestyle.

How often should I get the flu shot?

You should get the flu vaccine every year since flu viruses constantly evolve, and the vaccine is updated annually to protect against new strains.

Is the flu vaccine safe?

Yes, the flu vaccine is extensively tested and recommended by global health organizations like WHO and CDC. Most people experience only mild side effects, if any.

What are the common side effects?

Common side effects include soreness, redness, and swelling at the injection site, as well as low-grade fever, headache, and muscle aches. These side effects are usually mild and go away on their own.

Who needs the flu shot the most?

While everyone above 6 months should get vaccinated, it’s especially crucial for young children, elderly individuals, pregnant women, and those with chronic illnesses.

Can healthy adults skip the flu vaccine?

No, even healthy adults can get the flu and spread it to vulnerable individuals. The vaccine reduces your chances of getting sick and helps protect your community.

Who should NOT take the flu vaccine?

People with severe allergies to any flu shot ingredients or those who had a serious reaction to a previous dose should consult a doctor before getting vaccinated.

Can I take the flu shot if I have a cold?

If you have mild cold symptoms, you can still get vaccinated. However, if you have a fever or feel very unwell, it’s best to wait until you recover.

Can we take other brand flu vaccines?

Yes, you can get the other brand FLU vaccine. WHO’s plays an important role in maintaining uniformity in Influenza Vaccine Strains with all the manufacturers. So, all the flu vaccines contain same strains, you have to choose the latest influenza vaccine available in the marketplace.

Flu Season in India - When and What to Expect

Zydus
May 8, 2026

Ever caught the flu in the middle of summer and thought, “How is this even possible?” A runny nose in winter feels normal, but a high fever and body aches during the monsoon or late summer is unexpected. In India, flu symptoms often show up when we least expect them, which is why many people don’t know when flu spreads.

Most of us believe that the flu happens only in winter. But the truth is, flu season in India does not follow a single calendar.1 This happens because of our diverse climate; flu viruses behave differently across regions. In some areas, flu cases spike during colder months, while in others, they rise with humidity and rainfall.1 That’s why the flu season months can vary widely from one city to another.

What is Flu and Why Seasonality Matters

Influenza, or the flu, is often mistaken for a common cold. Both can cause a runny nose, cough, or sore throat, but the flu usually hits harder. High fever, body aches, extreme fatigue, and headaches are more common with influenza, and symptoms tend to come on suddenly rather than gradually, as they do with a cold.2

So why does the flu seem to show up at different times of the year? The answer lies in how flu viruses respond to changes in weather and environment. Temperature, humidity, rainfall, and how much time people spend indoors all affect how easily the virus spreads.1 This is why the flu season in India does not look the same everywhere and why the flu season months vary by region.

Flu Seasons Across Different Parts of India

The flu season in India does not follow a single pattern because flu activity is influenced by latitude and local climate conditions rather than administrative regions.1

Higher-latitude regions with colder winters

In parts of India located at higher latitudes, such as Jammu and Kashmir, flu activity tends to follow a clear winter pattern.1,3

Typical flu peak: December to March1,3

Key drivers: Lower temperatures and cold, dry air3

Observed pattern: Similar to the flu seasonality as seen in temperate countries.

In these regions, influenza circulation increases during colder months, closely resembling winter flu trends observed in Europe and other Northern Hemisphere countries.3

Lower-latitude, monsoon-influenced regions

In regions located at lower latitudes, flu activity is more closely linked to the monsoon and post-monsoon period rather than winter.1

Typical flu peak: During or shortly after the monsoon, often August to October. 1

Key drivers: Rainfall and higher humidity. 1

Surveillance data from urban centers in northern and central India shows that influenza activity in these regions correlates more strongly with rainfall patterns than with the colder temperatures. 1,3

Regions with prolonged or overlapping flu activity

Some parts of India do not experience a single, sharply defined flu season. Instead, flu activity may be prolonged or occur in more than one phase during the year. 1

Observed pattern: Extended or overlapping flu circulation. 1

Contributing factors: Warm temperatures, humidity, and longer monsoon periods

In these areas, flu can feel almost “year-round,” making early and timely prevention especially important. 1

These variations help explain why the flu season months can feel less defined in certain cities. At a broad level:

Winter-driven areas tend to see flu peaks during colder months

Monsoon-driven areas often experience higher flu activity during or after the rainy season

Common Symptoms to Watch Out for During Flu Season in India

Flu symptoms often come suddenly and can feel much more intense than a common cold, especially during peak flu activity. Being able to recognise these early signs can help you take timely action. Common flu symptoms include:

Fever, often high and sudden2

Cough and sore throat2

Body aches, fatigue, and headache2

During the flu season in India, symptoms may worsen quickly because virus circulation is higher. Fatigue can be severe, body aches may limit daily activity, and fever may last longer than expected. In some cases, flu symptoms can become more serious.2

Who Is Most at Risk During Flu Season in India?

While flu can affect anyone, some people are more likely to develop complications during the flu season in India. Groups at higher risk include:

Children below 5 years of age2, whose immune systems are still developing

Older adults, as immunity tends to weaken with age2

Pregnant women, who are more vulnerable to severe illness during pregnancy2

People with chronic conditions such as asthma, diabetes, or heart disease2

For these groups, flu can lead to complications like severe respiratory illness, longer recovery times, or the need for hospital care. This is why flu season can be more dangerous for them compared to healthy adults. 2

How to Prepare for Flu Season in India

Preparing early is important, especially since the flu season in India varies by region. While everyday habits like regular handwashing, masking when unwell, and avoiding crowded indoor spaces during peak flu season months can help reduce exposure, they don’t offer complete protection.2

The most important and effective step in preparing for flu season is Annual Flu Vaccination. Flu viruses change over time, and the immunity provided by the vaccine gradually reduces.1 This is why vaccination is needed every year to maintain protection. Getting vaccinated annually aims to ensure that your immune system is prepared before flu activity begins to rise, reducing the risk of infection and serious illness.

Why the Timing of Flu Vaccination Matters

Flu vaccination does not provide instant protection. After vaccination, the body takes about two weeks to develop protective antibodies, and this immunity gradually wanes over the months.4 This makes timing especially important in India, where flu circulation does not follow one fixed season. Regions that experience winter flu peaks may benefit from pre-winter vaccination, while areas with monsoon-related flu activity may benefit from pre-monsoon vaccination.1 Vaccinating at the right time helps ensure protection is strongest when flu cases are most likely to increase.

Protect Yourself Before Flu Season Peaks

India does not have one fixed flu season, and flu activity varies by region, climate, and geography.1 Understanding local flu patterns allows people to take preventive steps at the right time. Early preparation is more effective than reacting to illness, and Annual Flu Vaccination remains the most reliable way to reduce the risk of influenza and its complications.
Talk to your doctor about India Flu Protection and take the vaccine to get protected based on your local flu season.

References:
1. Seasonality of Influenza and Optimizing Timing of Vaccination: Systematic Review and Meta-Analysis- Padhi, A., Bhatt, P., Chauhan, J., Rajyaguru, B., Agarwal, S., Chaudhary, A., Bhise, M., & Agarwal, A. (2025). Seasonality of Influenza and Optimizing Timing of Vaccination: Systematic Review and Meta-Analysis. Cureus, 17(9), e93607. https://doi.org/10.7759/cureus.93607
2. https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal)
3. Differences in Influenza Seasonality by Latitude, Northern India- Koul, P. A., Broor, S., Saha, S., Barnes, J., Smith, C., Shaw, M., Chadha, M., & Lal, R. B. (2014). Differences in Influenza Seasonality by Latitude, Northern India. Emerging Infectious Diseases, 20(10), 1723. https://doi.org/10.3201/eid2010.140431 https://pmc.ncbi.nlm.nih.gov/articles/PMC4193176/
4. https://www.cdc.gov/flu/vaccines/keyfacts.html?CDC_AAref_Val=https://www.cdc.gov/flu/prevent/keyfacts.htm