A Phase 4 interventional study of High-dose influenza vaccine and Standard-dose influenza vaccine in Influenza, sponsored by Tan Tock Seng Hospital. Not yet recruiting at 1 site in Singapore. Open to participants aged 60 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Tan Tock Seng Hospital · Phase 4, Interventional, and Prevention
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:
Participants will:
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.
2,264 studies on the registry are indexed under Influenza, Human; 173 are open to participants now.
This study's planned enrollment of 150 is below the median of 240 across 1,894 interventional studies indexed under Influenza, Human.
Browse Influenza, Human studies →Tan Tock Seng Hospital is the lead sponsor of 108 studies on the registry; 19 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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Exclusion Criteria:
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
a. Note: mild allergic reactions (like hives) after eating eggs are not a contraindication to influenza vaccination or study enrolment
Trivalent, high-dose inactivated influenza vaccine
Biological: High-dose influenza vaccine
Trivalent, standard-dose inactivated influenza vaccine
Biological: Standard-dose influenza vaccine
Each dose contains 60 mcg haemagglutinin of each of the 3 influenza vaccine strains.
Also known as: Fluzone high-dose, Efluelda
Each dose contains 15 mcg haemagglutinin of each of the 3 influenza vaccine strains.
Also known as: Fluzone, Vaxigrip
GMT ratio (HD-IIV/SD-IIV) for A/H3N2 strain in the vaccine
Time frame: Day 14
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
Seroprotection is defined as HI titre ≥1:40
Time frame: 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.
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
Number of subjects reporting influenza like illness (ILI)
Time frame: Day 14 to 330
Number of subjects with confirmed influenza infection
Influenza infection confirmed by lateral flow assay (LFA) and/or polymerase chain reaction (PCR)
Time frame: Day 14 to 330
Plan to share: 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.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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