Influenza Vaccination 101
What is influenza and how will it affect me?
Seasonal influenza, commonly called “the flu”, is caused by influenza viruses. Symptoms include sudden fever, chills, body aches, sore throat, cough, and headache. Transmission occurs through respiratory droplets during coughing and sneezing. Unlike the common cold virus, influenza can potentially cause severe illness and life-threatening complications especially in older people, young children, pregnant women, and those with certain health conditions.
Who should take the influenza vaccination?
The flu vaccine is recommended for ALL healthy adults, children (six months and above), frequent travellers, and caregivers. It is strongly recommended for the following groups of people who are at higher risk of complications:
- Elderly people 65 years and above
- Young children from six months to under five years of age
- Pregnant women at all stages of pregnancy
- People with chronic medical conditions (e.g. heart and lung diseases, chronic liver and kidney diseases, diabetes, stroke, dementia, Parkinson’s disease, intellectual disability etc.)
- People with blood disorders (e.g. leukaemia, lymphoma, multiple myeloma, and thalassemia major)
- People with chronically suppressed immunity due to disease, cancer treatment, or long-term medication such as corticosteroids or biologics
- People who stay in intermediate or long-term care facilities (nursing homes, hospices etc.)
- Children and adolescents aged six months to 18 years who are receiving long-term aspirin therapy
In addition, persons staying in close-living environments should also undergo influenza vaccination. They include:
- Foreign workers living in all forms of dormitories and private residential premises
- Staff working in the following facilities:
- Custodial and residential facilities, such as homes and shelters
- Communal living facilities
- Cruises, ferries
- Hostels, such as boarding and guest houses
Read also 5 myths to debunk about flu vaccines
Is there a waiting interval between taking the influenza vaccine and covid-19 vaccine?
A person can be vaccinated with COVID-19 vaccine, even if the person had received a non-COVID-19 vaccine (e.g. influenza vaccine) within 14 days of the COVID-19 vaccination. An interval of at least 14 days before or after a non-COVID-19 vaccine is encouraged.
What are the influenza vaccines currently available in Singapore?
The quadrivalent influenza vaccine is the most common vaccine-type administered in Singapore. It is often injected into the Deltoid muscle of the upper arm or the outer aspect of the thigh. It protects against two ‘A’ strains and two ‘B’ strains of influenza. The influenza vaccine is released twice a year – in second quarter (Southern Hemisphere, SH) and the fourth quarter period (Northern hemisphere, NH ). Each new release incorporates the latest circulating Influenza A and B strains, based on surveillance data from the World Health Organisation.
What is the current recommendation for flu vaccination?
The latest 2026 Southern Hemisphere (SH) influenza vaccine differs from previous seasons’ vaccines in that its influenza A(H1N1) and A(H3N2) components have been revised, representing a two-strain change. Hence, persons in the recommended groups who received earlier influenza vaccines, such as the 2025 SH vaccine (April to September 2025), the 2025/26 Northern Hemisphere (NH) vaccine (October 2025 to March 2026), or any earlier influenza vaccine, should receive the 2026 SH influenza vaccine (April to September 2026) for more complete protection against currently circulating strains. For optimal protection, vaccination is recommended early in the season. Persons who received the 2025/26 NH vaccine may receive the 2026 SH vaccine after a minimum interval of eight weeks.
The current composition of the 2026 SH seasonal influenza vaccine (egg-based) is as follows:
- an A/Missouri/11/2025 (H1N1)pdm09-like virus (new)
- an A/Singapore/GP20238/2024 (H3N2)-like virus (new)
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
- a B/Phuket/3073/2013 (B / Yamagata lineage)-like virus
What are some common side effects of the flu vaccine?
Some common side effects include headache, body aches, fatigue, redness, swelling, and pain over the injection site. However, these occur in less than 10 per cent of vaccinated patients, are often mild, and will resolve by themselves.
Are there serious side effects associated with the flu vaccine?
Serious side effects occur very rarely and are much lower than the risk of having severe complications from influenza. These include:
- Allergic reactions leading to rash, low blood pressure, facial swelling and breathlessness.
- Blood vessel and blood disorders such as lowered platelet levels and blood vessel inflammation, lymph node swelling.
- Nervous system disorders such as fits and progressive muscle weakness (Guillain-Barre Syndrome) which are extremely rare at one in a million cases.
When should I avoid the flu vaccination?
- If you are feeling unwell or having a fever
- If you are known to have a severe allergy to antibiotics such as neomycin, gentamicin, and polymyxin B
- If you previously had a severe allergic reaction to the influenza vaccine, regardless of the component suspected to be responsible for the reaction
- Persons who have a history of severe egg allergy (i.e. symptoms other than hives) are recommended to have the flu vaccination done in a controlled hospital setting
Where can I receive the influenza vaccination?
The latest 2026 SH influenza vaccine is available at most Raffles Medical clinics. Alternatively, they can also be purchased online before visiting the clinic.
Is the seasonal influenza vaccination chargeable for patient’s enrolled under Healthier SG?
Under Healthier SG, eligible individuals with selected health conditions (e.g. diabetes, kidney disease, lung conditions etc. or if they are 65 and above) can receive the influenza vaccination for free at the Raffles Medical clinic they have chosen to be enrolled in.
The article is reviewed by Dr Benjamin Lee, Specialist in Family Medicine, Raffles Medical.
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