InfluenzaPhase 4SingVax-01NCT07883421
Immunogenicity of Standard-Dose Versus High-Dose Influenza Vaccines in Older Adults in Singapore
A Phase 4 study testing High-dose influenza vaccine and Standard-dose influenza vaccine in people with Influenza, run by Tan Tock Seng Hospital at 1 site in Singapore.
Trial summary
The goal of this clinical trial is to learn if the high-dose influenza vaccine can improve year-round protection in older adults aged 60 years and above. The main question it aims to answer is: Can the high-dose influenza vaccine induce higher antibody titres at Day 14 post-vaccination compared to standard-dose… Read more about this study
- Who is it for?
- Ages 60 years and olderHealthy volunteers can take part
- Conditions the study is for
- Influenza
- What is being tested?
- High-dose influenza vaccine and Standard-dose influenza vaccine
- Type of treatment
- Vaccines
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 150 participants
- Where
- 1 siteSingapore
- Study dates
- Nov 2026to Mar 2028
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 60 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Willing and able to provide written informed consent
- Aged ≥60 years at the time of study enrolment
- No influenza vaccination in the previous 8 months
- Able to attend all visits and comply with study procedures
- Owns a mobile phone
Who cannot join
- History of a severe allergic reaction (e.g. anaphylaxis) to any component of the vaccine, including egg protein, or after any previous dose of any influenza vaccine, including a History of Guillain-Barré syndrome (GBS) within 6 weeks following previous influenza vaccination
- Note: mild allergic reactions (like hives) after eating eggs are not a contraindication to influenza vaccination or study enrolment
- Moderate or severe acute illness/infection (according to investigator judgement) on the day of vaccination, or febrile illness (temperature ≥ 37.5°C). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided.
- Self-reported thrombocytopenia, contraindicating IM vaccination
- Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding six months; or long-term systemic corticosteroid therapy (prednisolone ≥ 7.5mg/day or equivalent for more than 2 consecutive weeks within the past 3 months)
- Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
- Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
- Current alcohol abuse or drug addiction that might interfere with the ability to comply with trial procedures in the opinion of the Investigator
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Jia Yi Hee, PhD contact
Singapore1 site
National Centre for Infectious Diseases (NCID)
Singapore
Xuan Ying Poh, PhD, +65 6511 5090, poh.xuan.ying@nhghealth.com.sg
Jia Yi Hee, PhD, hee.jia.yi@nhghealth.com.sg
About this study
Official title: Evaluating the Year-Round Immunogenicity of Standard-Dose Versus High-Dose Seasonal Influenza Vaccines in Adults Aged 60 Years or Older in Singapore
The goal of this clinical trial is to learn if the high-dose influenza vaccine can improve year-round protection in older adults aged 60 years and above. The main question it aims to answer is:
- Can the high-dose influenza vaccine induce higher antibody titres at Day 14 post-vaccination compared to standard-dose influenza vaccine?
Read more
Participants will:
- Receive one dose of either the high-dose or standard-dose influenza vaccine
- Be followed for one year, with four scheduled visits
- Keep a diary of their symptoms for 3 days after vaccination
- Report symptoms whenever they experience an acute respiratory infection (ARI), self-perform lateral flow assay (LFA) testing capable of detecting influenza A and B, and send nasal swabs for central testing
Read the detailed description
The immunogenicity and effectiveness of seasonal influenza vaccination declines with increasing age of the vaccinee. Singapore's resident population is aging, with the median resident age rising from 35.8 years two decades ago to 43.2 years in 2025. By 2035, it is estimated that about a third of Singaporeans will be aged 65 and above.
Unlike temperate countries where influenza epidemics characteristically occur during the cold winter months, influenza virus activity in tropical climates is more variable and complex. In Singapore, biannual epidemics are usual, but with continuous transmission year-round. The traditional standard-dose inactivated influenza vaccine (SD-IIV) is unlikely to provide older adults with the year-round protection necessary for Singapore and other tropical countries with a similar climate and disease epidemiology.
In countries where the high-dose inactivated influenza vaccine (HD-IIV) is available, national vaccination programmes generally recommended it in preference to the SD-IIV for older adults (e.g. US CDC, Australian government, UK Health Security Agency). This reflects the evidence from randomised clinical trials that the HD-IIV vaccine is superior to the SD-IIV at reducing rates of infection and serious complications such as hospital admission. However, none of these studies have been conducted in a tropical setting, an important evidence gap for policy makers when considering vaccination recommendations.
The SingVax-01 trial is a single-centre, randomised controlled, observer-blind, parallel-group Phase IV trial in 150 adults aged ≥60 years. It will examine the hypothesis that a single intramuscular injection of a HD-IIV offers higher vaccine strain specific haemagglutination inhibition (HI) geometric mean titres (GMTs) at 14-28 days after vaccination compared with the SD-IIV. By assessing the magnitude and durability of immune responses over a 12-month period, this study seeks to generate evidence to inform vaccine policy and optimize influenza prevention strategies for older adults in Singapore as well as other tropical settings to ensure sustained protection against influenza year-round.
- Conditions
- Influenza
- Being tested
- High-dose influenza vaccine, Standard-dose influenza vaccine
- Keywords
- standard-dose inactivated influenza vaccine, high-dose inactivated influenza vaccine, A(H3N2), Efluelda, Fluzone, Fluzone high-dose, Vaxigrip, acute respiratory illness, immunogenicity
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
High-dose influenza vaccineBiological
Also called Fluzone high-dose, Efluelda
Each dose contains 60 mcg haemagglutinin of each of the 3 influenza vaccine strains.
Standard-dose influenza vaccineBiological
Also called Fluzone, Vaxigrip
Each dose contains 15 mcg haemagglutinin of each of the 3 influenza vaccine strains.
| Study group | Role | What they receive |
|---|---|---|
| HD-IIV | Experimental | Trivalent, high-dose inactivated influenza vaccine Receives: Biological: High-dose influenza vaccine |
| SD-IIV | Active comparator | Trivalent, standard-dose inactivated influenza vaccine Receives: Biological: Standard-dose influenza vaccine |
What is being measured
The primary outcome is the main question the study is designed to answer.
GMT ratio (HD-IIV/SD-IIV) for A/H3N2 strain in the vaccine
Measured: Day 14
Secondary outcomes (11)
GMT ratio (HD-IIV/SD-IIV) for A/H3N2 strain in the vaccine
Measured: Day 180 and 330
GMT ratio (HD-IIV/SD-IIV) for A/H1N1 strain in the vaccine
Measured: Day 14, 180 and 330
GMT ratio (HD-IIV/SD-IIV) for B/Victoria strain in the vaccine
Measured: Day 14, 180 and 330
HI GMTs against influenza vaccine strains
Measured: Day 14, 180 and 330
Geometric mean ratio (GMR) of HI titres post- versus pre-vaccination against vaccine strains
Measured: Day 14 to 330
Seroprotection rates against vaccine strains
Seroprotection is defined as HI titre ≥1:40
Measured: Day 14 to 330
Seroconversion rates against vaccines strains
Seroconversion is defined as a pre-vaccination (Day 0) HI titre <10 and post-vaccination HI titre ≥40 or at least a 4-fold increase in HI titres from a pre-vaccination HI titre ≥10.
Measured: Day 14 to 330
Micro-neutralization titres against vaccine strains
Measured: Day 14, 180 and 330
Frequency of solicited local (injection site) and systemic adverse events
Measured: 3 days post-vaccination
Severity of solicited local (injection site) and systemic adverse events
Measured: 3 days post-vaccination
Percentage of subjects with serious adverse events (SAEs)
Measured: Day 0 to 330
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Oct 2026
- Study startNov 2026 (estimated)
- Primary completionMar 2027 (estimated)
- Study completionMar 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for InfluenzaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 150 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tan Tock Seng Hospital
- Sponsor type
- University, hospital or other
- Collaborators
- A*STAR Infectious Diseases Labs, World Health Organization Collaborating Centre for Reference and Research on Influenza (WHOCCRRI)
- Responsible party
- Sponsor
- Investigators
- Barnaby E Young, MB BChir, PhD, Principal investigator, National Centre for Infectious Diseases (NCID)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07883421
- Sponsor's protocol ID
- 2026/0684
- Acronym
- SingVax-01
- Status last verified
- Oct 2026
- First submitted
- 13 Oct 2026
- Last updated
- 20 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: All study findings and documents will be regarded as confidential. The investigators and other study personnel must not disclose such information without prior written approval from the PI. Participant confidentiality will be strictly maintained to the extent possible under the law and local hospital policy. Identifiable information will be removed from any published data.
Publications
DiazGranados CA, Dunning AJ, Kimmel M, Kirby D, Treanor J, Collins A, Pollak R, Christoff J, Earl J, Landolfi V, Martin E, Gurunathan S, Nathan R, Greenberg DP, Tornieporth NG, Decker MD, Talbot HK. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014 Aug 14;371(7):635-45. doi: 10.1056/NEJMoa1315727.
PubMed 25119609Cheng C, Chen X, Ge Y, Sung MH, Zhang Y, Ogunyemi K, Carlock MA, Hanley HB, Handel A, Ross TM, Shen Y. Assessing factors associated with one-year antibody waning in participants with repeated influenza vaccinations: A six-year cohort study. Vaccine. 2025 Dec 5;68:127904. doi: 10.1016/j.vaccine.2025.127904. Epub 2025 Nov 6.
PubMed 41202613Young B, Sadarangani S, Jiang L, Wilder-Smith A, Chen MI. Duration of Influenza Vaccine Effectiveness: A Systematic Review, Meta-analysis, and Meta-regression of Test-Negative Design Case-Control Studies. J Infect Dis. 2018 Feb 14;217(5):731-741. doi: 10.1093/infdis/jix632.
PubMed 29220496
Study at a glance
From the registry record, last updated by the sponsor on 20 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluating the Year-Round Immunogenicity of Standard-Dose Versus High-Dose Seasonal Influenza Vaccines in Adults Aged 60 Years or Older in Singapore
- ClinicalTrials.gov ID
- NCT07883421
- Acronym / sponsor ID
- SingVax-01 / 2026/0684
- Conditions
- Influenza
- Keywords
- standard-dose inactivated influenza vaccine, high-dose inactivated influenza vaccine, A(H3N2), Efluelda, Fluzone, Fluzone high-dose, Vaxigrip, acute respiratory illness
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 150 participants (estimated)
- Lead sponsor
- Tan Tock Seng HospitalUniversity, hospital or other
- Collaborators
- A*STAR Infectious Diseases Labs, World Health Organization Collaborating Centre for Reference and Research on Influenza (WHOCCRRI)
- Study start
- Nov 2026 (estimated)
- Primary completion
- Mar 2027 (estimated)
- Study completion
- Mar 2028 (estimated)
- First posted
- 20 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to learn if the high-dose influenza vaccine can improve year-round protection in older adults aged 60 years and above. The main question it aims to answer is:
- Can the high-dose influenza vaccine induce higher antibody titres at Day 14 post-vaccination compared to standard-dose influenza vaccine?
Participants will:
- Receive one dose of either the high-dose or standard-dose influenza vaccine
- Be followed for one year, with four scheduled visits
- Keep a diary of their symptoms for 3 days after vaccination
- Report symptoms whenever they experience an acute respiratory infection (ARI), self-perform lateral flow assay (LFA) testing capable of detecting influenza A and B, and send nasal swabs for central testing
Detailed description
The immunogenicity and effectiveness of seasonal influenza vaccination declines with increasing age of the vaccinee. Singapore's resident population is aging, with the median resident age rising from 35.8 years two decades ago to 43.2 years in 2025. By 2035, it is estimated that about a third of Singaporeans will be aged 65 and above.
Unlike temperate countries where influenza epidemics characteristically occur during the cold winter months, influenza virus activity in tropical climates is more variable and complex. In Singapore, biannual epidemics are usual, but with continuous transmission year-round. The traditional standard-dose inactivated influenza vaccine (SD-IIV) is unlikely to provide older adults with the year-round protection necessary for Singapore and other tropical countries with a similar climate and disease epidemiology.
In countries where the high-dose inactivated influenza vaccine (HD-IIV) is available, national vaccination programmes generally recommended it in preference to the SD-IIV for older adults (e.g. US CDC, Australian government, UK Health Security Agency). This reflects the evidence from randomised clinical trials that the HD-IIV vaccine is superior to the SD-IIV at reducing rates of infection and serious complications such as hospital admission. However, none of these studies have been conducted in a tropical setting, an important evidence gap for policy makers when considering vaccination recommendations.
The SingVax-01 trial is a single-centre, randomised controlled, observer-blind, parallel-group Phase IV trial in 150 adults aged ≥60 years. It will examine the hypothesis that a single intramuscular injection of a HD-IIV offers higher vaccine strain specific haemagglutination inhibition (HI) geometric mean titres (GMTs) at 14-28 days after vaccination compared with the SD-IIV. By assessing the magnitude and durability of immune responses over a 12-month period, this study seeks to generate evidence to inform vaccine policy and optimize influenza prevention strategies for older adults in Singapore as well as other tropical settings to ensure sustained protection against influenza year-round.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| HD-IIV | Experimental | Biological: High-dose influenza vaccineTrivalent, high-dose inactivated influenza vaccine |
| SD-IIV | Active comparator | Biological: Standard-dose influenza vaccineTrivalent, standard-dose inactivated influenza vaccine |
Who may qualify
- Ages
- 60 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Willing and able to provide written informed consent
- Aged ≥60 years at the time of study enrolment
- No influenza vaccination in the previous 8 months
- Able to attend all visits and comply with study procedures
- Owns a mobile phone
Key exclusion criteria (8 listed)
- History of a severe allergic reaction (e.g. anaphylaxis) to any component of the vaccine, including egg protein, or after any previous dose of any influenza vaccine, including a History of Guillain-Barré syndrome (GBS) within 6 weeks following previous influenza vaccination
- Moderate or severe acute illness/infection (according to investigator judgement) on the day of vaccination, or febrile illness (temperature ≥ 37.5°C). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided.
- Self-reported thrombocytopenia, contraindicating IM vaccination
- Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding six months; or long-term systemic corticosteroid therapy (prednisolone ≥ 7.5mg/day or equivalent for more than 2 consecutive weeks within the past 3 months)
- Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| High-dose influenza vaccineAlso: Fluzone high-dose, EflueldaEach dose contains 60 mcg haemagglutinin of each of the 3 influenza vaccine strains. | Biological | HD-IIV |
| Standard-dose influenza vaccineAlso: Fluzone, VaxigripEach dose contains 15 mcg haemagglutinin of each of the 3 influenza vaccine strains. | Biological | SD-IIV |
Primary outcome
GMT ratio (HD-IIV/SD-IIV) for A/H3N2 strain in the vaccine
Time frame: Day 14
11 secondary outcomes
GMT ratio (HD-IIV/SD-IIV) for A/H3N2 strain in the vaccine
Time frame: Day 180 and 330
GMT ratio (HD-IIV/SD-IIV) for A/H1N1 strain in the vaccine
Time frame: Day 14, 180 and 330
GMT ratio (HD-IIV/SD-IIV) for B/Victoria strain in the vaccine
Time frame: Day 14, 180 and 330
HI GMTs against influenza vaccine strains
Time frame: Day 14, 180 and 330
Geometric mean ratio (GMR) of HI titres post- versus pre-vaccination against vaccine strains
Time frame: Day 14 to 330
Seroprotection rates against vaccine strains
Time frame: Day 14 to 330
Seroconversion rates against vaccines strains
Time frame: Day 14 to 330
Micro-neutralization titres against vaccine strains
Time frame: Day 14, 180 and 330
Frequency of solicited local (injection site) and systemic adverse events
Time frame: 3 days post-vaccination
Severity of solicited local (injection site) and systemic adverse events
Time frame: 3 days post-vaccination
Percentage of subjects with serious adverse events (SAEs)
Time frame: Day 0 to 330
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Oct 2026.
- Background: PubMed 25119609DiazGranados CA, Dunning AJ, Kimmel M, Kirby D, Treanor J, Collins A, Pollak R, Christoff J, Earl J, Landolfi V, Martin E, Gurunathan S, Nathan R, Greenberg DP, Tornieporth NG, Decker MD, Talbot HK. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014 Aug 14;371(7):635-45. doi: 10.1056/NEJMoa1315727.
- Background: PubMed 41202613Cheng C, Chen X, Ge Y, Sung MH, Zhang Y, Ogunyemi K, Carlock MA, Hanley HB, Handel A, Ross TM, Shen Y. Assessing factors associated with one-year antibody waning in participants with repeated influenza vaccinations: A six-year cohort study. Vaccine. 2025 Dec 5;68:127904. doi: 10.1016/j.vaccine.2025.127904. Epub 2025 Nov 6.
- Background: PubMed 29220496Young B, Sadarangani S, Jiang L, Wilder-Smith A, Chen MI. Duration of Influenza Vaccine Effectiveness: A Systematic Review, Meta-analysis, and Meta-regression of Test-Negative Design Case-Control Studies. J Infect Dis. 2018 Feb 14;217(5):731-741. doi: 10.1093/infdis/jix632.
- Individual participant dataSharing planned: No. All study findings and documents will be regarded as confidential. The investigators and other study personnel must not disclose such information without prior written approval from the PI. Participant confidentiality will be strictly maintained to the extent possible under the law and local hospital policy. Identifiable information will be removed from any published data.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Jia Yi Hee, PhD contact
Barnaby E Young, MB BChir, PhD principal investigator
National Centre for Infectious Diseases (NCID)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing High-dose influenza vaccine and Standard-dose influenza vaccine in people with Influenza, run by Tan Tock Seng Hospital at 1 site in Singapore.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 20 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Singapore. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Xuan Ying Poh, PhD (+65 6511 5090, poh.xuan.ying@nhghealth.com.sg), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
GMT ratio (HD-IIV/SD-IIV) for A/H3N2 strain in the vaccine (time frame: Day 14). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07883421, which also lists 3 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 Oct 2026.