Phase 3
Completed N=601
Evaluation of Full Versus Fractional Dose of COVID-19 Vaccine Given as a Booster for the Prevention of COVID-19 in Adults in Mongolia.
Source: ClinicalTrials.gov NCT05265065 ↗Enrolled (actual)
601
Serious AEs
0.8%
Results posted
Sep 2024
Primary outcomePrimary: Seroresponse — 253; 250 Participants
◆ Published Evidence
Emerging
10citations · ~5 / year
Immunogenicity, safety, and reactogenicity of a half- versus full-dose BNT162b2 (Pfizer-BioNTech) booster following a two-dose ChAdOx1 nCoV-19, BBIBP-CorV, or Gam-COVID-Vac priming schedule in Mongolia: a randomised, controlled, non-inferiority trial.
Summary
This clinical trial is a single-blind, randomised study to determine the reactogenicity and immunogenicity of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) vaccine (Pfizer-BioNTech) as booster dose in adults, who have previously received either Sinopharm (BBIBP-CorV®), AstraZeneca (ChAdOx1-S, or Vaxzevria®) or Sputnik V (Gam-COVID-Vac®) as their primary doses 6 to 9 months earlier. Both standard and fractional doses will be tested.
Participants are healthy adults aged 18 years or older, with no upper age limit. Procedures will be implemented to ensure participants of all ages (aged 18 and above) are included and that there is an even age distribution (<50 and ≥50 years) in each group. There will be a total of 6 groups (Sinopharm-standard dose Pfizer, Sinopharm-fractional dose Pfizer, AstraZeneca-standard dose Pfizer, AstraZeneca-fractional dose Pfizer, Sputnik - standard dose Pfizer, Sputnik - fractional dose Pfizer), with 200 participants per group for Sinopharm and 100 for AstraZeneca and Sputnik.
Linked Publications (3)
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Immunogenicity, safety, and reactogenicity of a half- versus full-dose BNT162b2 (Pfizer-BioNTech) booster following a two-dose ChAdOx1 nCoV-19, BBIBP-CorV, or Gam-COVID-Vac priming schedule in Mongolia: a randomised, controlled, non-inferiority trial.
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Immunogenicity and safety at twelve months of fractional and standard BNT162b2 booster doses in adults primed with ChAdOx1-S, BBIBP-CorV, or Gam-COVID-Vac in Mongolia: a randomised controlled trial.
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Fractional BNT162b2 boosters induce durable immune responses after non-mRNA priming in Mongolia: a randomised controlled trial.
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Seroresponse |
253; 250 | — |
| PRIMARY Solicited Grade 3 or 4 Local or Systemic Reaction |
6; 4 | — |
| SECONDARY Seroresponse by Priming Vaccine Strata |
55; 52; 170; 169; 28; 29 | — |
| SECONDARY SARS-CoV-2 Specific IgG Antibodies at Day-28 |
4946; 4619 | 0.228 |
| SECONDARY SARS-CoV-2 Specific IgG Antibodies at Day-28 by Priming Vaccine Strata |
4394; 4167; 5109; 4970; 5160; 3662 | 0.537 |
| SECONDARY SARS-CoV-2 Specific IgG Antibodies at Baseline (Pre-booster), 28 Days, 6 Months, 12 Months, 18 Months, and 24 Months Post-booster Vaccination. |
969; 929; 4946; 4619; 2085; 2123 | — |
| SECONDARY SARS-CoV-2 Specific Neutralising Antibodies at Baseline (Pre-booster), 28 Days, 6 Months, 12 Months, 18 Months, and 24 Months Post-booster Vaccination Measured by Surrogate Virus Neutralisation Test (sVNT). |
81; 81; 81; 81; 89; 89 | — |
| SECONDARY SARS-CoV-2 Specific Neutralising Antibodies at Baseline (Pre Booster), 28 Days-, 6- and 12-months Post Booster Vaccination Measured by SARS-CoV-2 Microneutralisation Assay |
— | — |
| SECONDARY Interferon Gamma (IFNγ) Concentrations in International Units (IU)/mL |
0.26; 0.31; 0.46; 0.60; 0.27; 0.33 | — |
| SECONDARY Number of IFNγ Producing Cells/Million PBMCs |
— | — |
| SECONDARY Frequency of Cytokine-expressing T Cells |
— | — |
| SECONDARY Cellular Immunity: Multiplex Cytokine Assays - Reported as Cytokine Concentrations in pg/ml and Presented as GMC and 95% CI |
— | — |
| SECONDARY Incidence of Unsolicited Adverse Events (AE) |
5; 9; 12; 7; 5; 5 | — |
| SECONDARY Incidence of Medically Attended Adverse Events |
19; 16 | — |
| SECONDARY Incidence of Serious Adverse Events (SAE) |
6; 6; 17; 17; 4; 3 | — |
| SECONDARY Incidence of PCR Confirmed COVID-19 Infection |
14; 14 | — |
Eligibility Criteria
Inclusion Criteria
- Have completed two doses of Sinopharm, AstraZeneca or Sputnik vaccines with the recommended schedule 6 months prior to the date of enrolment
- Willing and able to give written informed consent
- Aged 18 years or above
- Willing to complete the follow-up requirements of the study
Exclusion Criteria
- Received 3 doses of COVID-19 vaccine
- Received 2 doses of COVID-19 less than 6 months prior to the start of the trial
- Currently on immunosuppressive medication or anti-cancer chemotherapy
- HIV infection
- Congenital immune deficiency syndrome
- Has received immunoglobulin or other blood products in the 3 months prior to vaccination
- Study staff and their relatives
- Have a history of a severe allergic reaction to any COVID-19 vaccines or have a medical exception to receiving further COVID-19 vaccines
Data sourced from ClinicalTrials.gov (NCT05265065) and the linked publication. Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication. Informational only — not medical advice.