Influenza Vaccine

To prevent influenza (including swine flu), doctors recommend the influenza vaccine annually, as it is the most effective method.

Why annually?–because the viruses that cause influenza are continuously mutating, and the vaccine is only effective

against the strains that compose the vaccines and the related strains. It is ineffective against unrelated strains and therefore it is vital that the vaccine covers the currently prevalent strains.

Who should get the flu vaccine?

All individuals > six months of age must receive the flu vaccine. Infants who are less than six months of age cannot mount an appropriate response to the vaccine. Therefore, we recommend that all caregivers who are in contact with infants less than six months of age definitely take the vaccine.

Are multiple doses required?

Since the strains that cause influenza illness vary every year, the flu vaccine needs to be repeated annually. For children younger than 9 years old, a doctor should administer a second vaccine dose at least one month after the first one during their initial flu season to maximize their immune response. If it is your child’s first time getting the flu shot (and they are under 9), they will need two doses, one month apart.

When should the flu vaccine be administered?

Ideally, one should administer it before influenza activity starts; if not possible, administer it as early as possible when the flu season begins. In India, the flu season is biphasic–one peak is in the monsoon months and one around January  and February though it can occur any time of the year in tropical regions like India. A doctor can give the vaccine at any time to a person who has not received it that year.

How effective is the vaccine?

First, it takes two weeks for the immunity to come through. Overall, 50%–80% of individuals who receive the vaccine will be protected against the illness.

Can I avoid taking a shot? Is there any other way to immunize myself?

The flu vaccine is available in two forms – the injection and the nasal spray. Vaccination guidelines approve the injection for individuals over 6 months old. They also approve the nasal spray for healthy children over 2 years old and healthy adults under 49 years old. For the 2025-2026 season, the nasal spray is a valid option for healthy individuals (non-pregnant) aged 2-49. The nasal spray is a great needle-free option for children over 2; however, its availability in India varies year-to-year. We recommend checking with us at the start of the season. Please call the clinic to check the current stock of the nasal spray if you prefer this needle-free option.

The CDC recommends either the flu shot or the nasal spray for healthy children, with no preference for one over the other.

High-Dose Options for Seniors: For adults aged 65 and older, specialized “high-dose” or “adjuvanted” vaccines are now the preferred recommendation. These vaccines specifically create a stronger immune response than the standard shot.

Why is there an emphasis on healthy individuals who receive nasal spray?

The nasal spray contains live viruses, which labs have weakened. If a person is sick or a female is pregnant, their weakened immune system may not defend them against the weakened virus, potentially causing them to develop the flu.

Are there any side-effects of the vaccine?

Yes, minor side-effects like soreness at the injection site, body-aches, low-grade fever (<38° C) and headache may occur and may last for a day or two. There are potentially major side-effects but these are extremely rare.

Allergy to the vaccine

Good news for families with egg allergies: recent global studies have confirmed that the flu vaccine is safe for everyone, regardless of the severity of an egg allergy. You no longer need to see a specialist or wait for extra observation time.

Are there no medicines available, other than the flu vaccine, that can prevent influenza?

Antiviral medications can help people exposed to the virus who haven’t received vaccinations. For various reasons, healthcare providers also administer them to high-risk groups who cannot receive vaccinations. There are significant side-effects to the drugs used, which makes this method undesirable for others.

Pregnant Women

All pregnant women must receive the influenza vaccine, and healthcare providers can administer it at any time during any trimester of pregnancy. The risk of complications and hospitalization is 4 times the normal in pregnancy, and this risk increases further along in the pregnancy. The vaccine not only protects the mother, but the protection extends to the baby up to the age of six months by transfer of antibodies.

If it is not fully effective, why should I give it to my child?

Vaccine efficacy varies every year. How many cases of influenza it prevented, measure this efficacy. The problem is that the influenza virus undergoes mutation all the time. The vaccine comprises the viral sub-types that were most prevalent last year. There is no guarantee that the same sub-types will be around this year too, explaining its less than complete efficacy. In recent seasons, the vaccine has been approximately 40% to 60% effective in preventing influenza illness.

So why give the vaccine?

Prevents or reduces the severity of the illness

Influenza is a severe illness and, in rare cases, can cause death too. In others, it makes you significantly sick, and you feel miserable and weak for days on end. Even if not 100% effective in preventing influenza, it decreases the severity of the breakthrough infection.

When the vaccine doesn’t prevent infection entirely, it is incredibly effective at preventing hospitalization. For the 2024-2025 season, effectiveness against hospitalization in children was as high as 60-70%

Protects others who cannot take the vaccine

Babies less than 6 months old and children receiving drugs such as steroids or anti-cancer drugs cannot receive the influenza vaccine. Their condition presents a double whammy, predisposing them to easily contracting influenza even with vaccination, should they encounter the influenza virus.
If adults or children receive full vaccination, they are less likely to contract influenza. This vulnerable population also receives the umbrella of protection from the influenza vaccine. What better way of being socially responsible?