A Singapore-isolated flu strain has been included in one of this year’s influenza vaccine formulations, highlighting Singapore’s role in global viral surveillance.
A/Singapore/GP20238/2024, an H3N2 virus, was selected by the World Health Organization (WHO) as a key reference virus for the egg-based 2026 Southern Hemisphere influenza vaccine. This highlights the continuous monitoring efforts by local health authorities to track viral mutations across the region.
Now, with flu activity rising across the island and an updated vaccine formulation arriving soon, many residents face a practical question when planning their annual health checks:
Should you get vaccinated now or wait?
Key Takeaways
- Singapore’s flu positivity rate reached 36.6% in August 2026, though the Communicable Diseases Agency (CDA) notes overall infection severity remains comparable to previous seasons.
- The 2026 Southern Hemisphere vaccine is currently available at polyclinics and participating CHAS GP clinics.
- The updated 2026–27 Northern Hemisphere vaccine is expected in early to mid-October and will be the preferred choice for recommended groups once available, due to its updated strain targeting.
- Individuals in high-risk groups who receive both formulations in the same year must observe a minimum spacing of eight weeks between doses to optimise immune response.
Understanding Singapore’s 2026 Flu Surge
- The surge in influenza positivity rates observed during mid-2026 aligns with Singapore’s typical mid-year viral peak. Unlike temperate regions that experience a single distinct winter flu season, tropical areas like Singapore encounter year-round viral circulation with bi-modal spikes. Surveillance data from the CDA indicates that while clinical consultations for influenza-like illnesses (ILI) have increased, hospitalisation rates and intensive care admissions have remained within expected baselines.
Why Does Singapore Have Two Flu Vaccine Formulations?
Due to its geographic location and global travel hub status, influenza circulates in Singapore throughout the year, with heightened activity typically during two main periods:
- May to August (coinciding with the Southern Hemisphere winter season)
- December to March (coinciding with the Northern Hemisphere winter season)
These periods broadly overlap with the Southern and Northern Hemisphere flu seasons.
Because influenza viruses continually evolve, WHO reviews circulating strains twice a year and updates its vaccine recommendations.
For the 2026 Southern Hemisphere season, the egg-based formulation includes an H3N2 component based on A/Singapore/GP20238/2024.
Vaccine Comparison: Southern vs. Northern Hemisphere Formulations
To choose the right timing, it helps to understand how the two annual vaccine formulations differ in composition and target availability:
- 2026 Southern Hemisphere Vaccine: Available from April/May through late primary stockpiles. Includes A/Singapore/GP20238/2024 (H3N2) strain. Best suited for immediate protection during mid-year spikes if not previously vaccinated.
- 2026–27 Northern Hemisphere Vaccine: Expected in Singapore clinics by early to mid-October 2026. Features two updated influenza strains based on worldwide genetic surveillance from mid-2026. Recommended as the primary option for upcoming travel or end-of-year flu season protection.
What About H3N2 Subclade K?
Another H3N2 variant, known as subclade K, spread rapidly internationally after emerging in 2025 and contributed to unusually early influenza activity in several countries.
That international trend helped drive the strain updates reflected in the upcoming 2026–27 Northern Hemisphere vaccine.
However, CDA has not identified subclade K as the cause of Singapore’s current increase.
There is also no indication that Singapore’s current flu infections are causing more severe disease or higher rates of complications than in standard flu seasons.
So, Which Vaccine Should You Get?
For people in groups recommended for annual influenza vaccination, the current guidance in Singapore is straightforward.
If You Have Not Received the 2026 Southern Hemisphere Vaccine
If you are at higher risk of severe influenza and want protection now, you can receive the available Southern Hemisphere vaccine.
MOH recommends that you still receive the updated Northern Hemisphere vaccine when it becomes available, leaving at least eight weeks between doses.
If You Already Received the 2026 Southern Hemisphere Vaccine
Wait for the 2026–27 Northern Hemisphere vaccine and maintain at least an eight-week interval between doses.
If You Have Not Been Vaccinated and Can Wait
The 2026–27 Northern Hemisphere vaccine is the preferred formulation for recommended groups once available.
It is expected to reach Singapore in early to mid-October 2026.
- Children aged six months to under five years
- People with certain underlying medical conditions
- Pregnant women at any stage of pregnancy
- Healthcare workers and caregivers living with vulnerable individuals
If you are unsure which option applies to you, speak with your doctor.
Where Can You Get Vaccinated?
Influenza vaccination is available through:
- Participating CHAS GP clinics
- Polyclinics
- Participating retail pharmacies for eligible adults
Healthier SG enrollees are encouraged to book through their enrolled clinic for subsidised rates and seamless record integration.
Do Precautions Still Matter?
Yes.
Vaccination reduces your risk but cannot prevent every flu infection.
If you develop respiratory symptoms:
- Stay home until you feel better where possible
- Wear a mask if you need to go out
- Avoid close contact with medically vulnerable people
Seek prompt medical evaluation if symptoms are severe, prolonged, or worsening—particularly for young children, elderly family members, or those with underlying chronic conditions.
The Bottom Line
If you belong to a recommended annual flu vaccination group and can wait briefly, the 2026–27 Northern Hemisphere vaccine is the preferred choice once it arrives in October.
However, if you are at higher risk, have not received any flu vaccine in the past 12 months, and require immediate protection due to travel or health status, obtaining the currently available Southern Hemisphere vaccine provides beneficial interim defence.
If you receive both, leave at least eight weeks between doses.
Unsure which applies to you? Speak with your doctor.
Sources
Communicable Diseases Agency Singapore. Update on Influenza Situation in Singapore. 2026.
https://www.cda.gov.sg/news-and-events/update-on-influenza-situation-in-singapore/
Hariyanto, Timotius Ivan. “Understanding Influenza A: Asian Epidemiology, Clinical Features, and Public Communication Challenges.” Influenza and Other Respiratory Viruses, 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC12887220/
Ministry of Health Singapore. Update on Seasonal Influenza Vaccination. 2026.
https://www.moh.gov.sg/newsroom/update-on-seasonal-influenza-vaccination/
World Health Organization. Recommended Composition of Influenza Virus Vaccines for Use in the 2026 Southern Hemisphere Influenza Season. 2025.
https://www.who.int/publications/m/item/recommended-composition-of-influenza-virus-vaccines-for-use-in-the-2026-southern-hemisphere-influenza-season
World Health Organization. Recommended Composition of Influenza Virus Vaccines for Use in the 2026–2027 Northern Hemisphere Influenza Season. 2026. https://www.who.int/publications/m/item/recommended-composition-of-influenza-virus-vaccines-for-use-in-the-2026-2027-northern-hemisphere-influenza-season
Editorial Note
This article is intended for general educational purposes and does not replace personalised medical advice. Influenza activity, vaccine availability and recommendations may change. Speak with a qualified healthcare professional about which influenza vaccine and timing are appropriate for you.