What is So Great About Flu Vaccinations?

Medically reviewed by Dr Jackie Lam, M.B.B.S (Singapore)

Influenza virus, also known as the flu, is a constantly evolving virus. Infections occur all year long with peaks in the middle and the beginning/end of the year. In Singapore, the Northern Hemisphere flu season usually occurs between November and February while the Southern Hemisphere season is from May to July. As the flu vaccine contains several strains of the flu virus which is expected to be common for that season, there are usually two flu vaccines that are available each year – the Northern Hemisphere flu vaccine and the Southern Hemisphere flu vaccine. Hence, it is strongly recommended to get vaccinated at least once per year to deal with this rapidly mutating virus.

What is Flu Vaccination?

The flu vaccination is a vaccine that is designed to protect individuals from the influenza virus. The vaccine works by exposing the individual to a small amount of the virus, which triggers the immune system to produce antibodies that can fight off the virus if the individual is exposed to it in the future.

What is the Common Flu Vaccine Used in Singapore?

Inactivated Quadrivalent Influenza Vaccine

The inactivated quadrivalent influenza vaccine is the most common type of flu vaccine in Singapore. It is a type of flu vaccination that contains four strains of the killed influenza virus. This vaccine is designed to provide protection against two strains of influenza A and two strains of influenza B. This vaccine is typically recommended for individuals six months of age and older. As this vaccine is made from the dead virus, it is not possible to get the flu from the vaccine. All the inactivated viruses do is to stimulate your immune system to make antibodies that would protect you from the influenza viruses. 

However, do talk to your doctors if you have a severe egg allergy or if you have had an allergic reaction to previous flu vaccinations.

Common Flu Vaccination Side Effects

Soreness and Swelling at the Injection Site, Headaches or Body Aches

One of the most common side effects of the flu vaccination is soreness and swelling at the injection site, body aches and/or headaches. These are normal reactions to the vaccine and are usually nothing to worry about. These symptoms typically go away on their own within a few days.


Some individuals may experience a low-grade fever after receiving the flu vaccination. This is a normal reaction to the vaccine and is usually nothing to worry about. The fever should go away on its own within a few days. You can also self-medicate with over-the-counter medicines if the fever persists. However, if the fever persists for more than 48 hours or it develops to be above 40°C, you should seek medical attention.


Fatigue is another common side effect of the flu vaccination. This is usually a mild fatigue and should go away on its own within a few days. Do remember to get lots of rest, hydrate and refrain from participating in strenuous activities until you are feeling better.


Some individuals may also experience nausea after receiving the flu vaccination. Though this is a rare side effect, it is usually still nothing to worry about. The nausea should go away on its own within a few days.

Allergic Reaction

In rare cases, individuals may experience an allergic reaction to the flu vaccination. Symptoms of an allergic reaction can include hives, difficulty breathing, and swelling of the face and throat. These symptoms can manifest as quickly as just a few minutes after the vaccination. If you experience any of these symptoms after receiving the flu vaccination, it is important to seek medical attention immediately. 

Which Flu Vaccination is Right for You?

The type of flu vaccination that is right for you will depend on a variety of factors, including your age, health status, and any allergies you may have. It is important to talk to your doctor about which flu vaccination is right for you.

Though there may be side effects, these effects are usually mild and symptoms will resolve on their own. If you have any concerns or worries, you can always raise them up to the doctor who can better advise you. 

Who Should Get the Flu Vaccine?

It is recommended that everyone above 6 months of age should get a flu vaccine at least once per year. As the influenza virus is constantly mutating, the flu vaccine from the previous season may not protect you through an upcoming flu season. Moreover, it is vital that you plan ahead and time your vaccination appointment well. The flu vaccine takes about 2 weeks to develop the antibodies needed for protection and immunity gets progressively weaker each subsequent month. Nonetheless, the yearly flu vaccination is usually sufficient for protection against the yearly flu season.

However, do take note that patients who are feeling unwell or are having a fever should delay their vaccination date.

Are There Any Subsidies?

Under the National Children Immunisation Scheme and the National Adult Immunisation Scheme, the Singapore government provides full subsidies on the annual flu vaccination for all Singaporeans if eligible.

Singaporeans considered eligible are:

  1. Children aged 6 to 59 months old
  2. Adults above 65 years of age
  3. Anyone above 6 months of age who is immunocompromised, with significant chronic illnesses or are on long term systemic steroid


Here at Keystone Clinic & Surgery, our doctors have plenty of experience administering the flu vaccine. We also regularly replenish our stocks to keep up to the dominant influenza variant. You can always consult our doctors for more advice or call us to book an appointment as the flu vaccine is usually in high demand. You can also check with us to see if you are eligible for any government subsidies.

Nevertheless, regardless of which type of flu vaccination you receive, getting vaccinated is the best way to protect yourself and those around you from the influenza virus. 


HealthHub. Influenza. 2022. https://www.healthhub.sg/a-z/diseases-and-conditions/103/topics_influenza 

Khoo Teck Puat – National University Children’s Medical Institute. Influenza Vaccination (Flu Jab) for Children with Diabetes. 2022. https://www.nuh.com.sg/our-services/Specialties/Paediatrics/Documents/Patient%20Information%20Sheet_Influenza%20Vaccination%20for%20Children%20with%20Diabetes_4%20Aug.pdf 

National Centre for Infectious Diseases. Influenza. 2023. https://www.ncid.sg/Health-Professionals/Diseases-and-Conditions/Pages/Influenza.aspx 

National Medication Information Workgroup. Influenza Vaccine. Healthhub. 2022. https://www.healthhub.sg/a-z/medications/367/Influenza-Vaccine 

Singapore General Hospital. Flu Vaccinations. HealthHub. 2021. https://www.healthhub.sg/a-z/diseases-and-conditions/724/Influenza-(Flu)-Vaccination-The-Best-Way-to-Avoid-Getting-the-Flu#1 

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