ArticleThe Lancet regional health. Western Pacific2024
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.
Article in The Lancet regional health. Western Pacific, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05265065 (A Randomised Controlled Trial to Assess the Immunogenicity, Safety and Reactogenicity of Standard Dose Versus Fractional Doses of COVID-19 Vaccine), which is not on this map. Cited by 7 papers.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
A Randomised Controlled Trial to Assess the Immunogenicity, Safety and Reactogenicity of Standard Dose Versus Fractional Doses of COVID-19 Vaccine (Pfizer-BioNTech) Given as a Booster Dose After Priming With Sinopharm, AstraZeneca or Sputnik in Healthy Adults in Mongolia
Who cites it
7 citing papers in PubMed.
- Fractional BNT162b2 boosters induce durable immune responses after non-mRNA priming in Mongolia: a randomised controlled trial.Frontiers in immunology · 2026Trial
- Cellular immune responses 12 months after fractional or standard dose BNT162b2 booster vaccination in Mongolian adults.Frontiers in immunology · 2026Trial
- Immunogenicity of fractional and standard dose COVID-19 vaccine boosters among healthy adults in Indonesia: twenty four month follow-up from a randomised controlled trial.Nature communications · 2025Trial
- Article
- Antispike IgG antibody decay after immunisation with fractional versus full booster doses of COVID-19 vaccines: a 6-month longitudinal analysis of the FRACT-COV trial in Brazil.BMJ public health · 2025Article
- Immunogenicity of Two Doses of BNT162b2 mRNA COVID-19 Vaccine with a ChAdOx1-S Booster Dose among Navy Personnel in Mexico.Viruses · 2024Article
- Immunogenicity and Safety of Half-Dose Heterologous mRNA-1273 Booster Vaccination for Adults Primed with the CoronaVacVaccines · 2024Article
Corrections and comments
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Authors and funding
28 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: COVID-19 vaccine booster doses restore vaccine effectiveness lost from waning immunity and emerging variants. Fractional dosing may improve COVID-19 booster acceptability and uptake and will reduce the per-dose cost of COVID-19 booster programmes. We sought to quantify the immunogenicity, reactogenicity, and safety of a half-dose BNT162b2 (Pfizer-BioNTech) booster relative to the standard formulation. Methods: This randomised, controlled, non-inferiority trial recruited adults in Mongolia primed with a two-dose homologous ChAdOx1 nCov-19 (Oxford-AstraZeneca, n = 129 participants), BBIBP-CorV (Sinopharm (Beijing), n = 399), or Gam-COVID-Vac (Gamaleya, n = 70) schedule. Participants were randomised (1:1) to receive a 15 μg (half-dose) or 30 μg (full-dose) BNT162b2 booster. Participants and study staff assessing reactogenicity were blinded up to day 28. Co-primary endpoints were Wuhan-Hu-1 anti-spike S1 IgG seroresponse 28 days post-boosting and reactogenicity within 7 days of boosting. The non-inferiority margin for the absolute difference in seroresponse was -10%. Differences in seroresponse were estimated from logistic regression with marginal standardisation. Geometric mean ratios of IgG were also estimated. ClinicalTrials.gov Identifier: NCT05265065. Findings: Between May 27th and September 30th, 2022, 601 participants were randomized to full-dose BNT162b2 (n = 300) or half-dose (n = 301). 598 were included in safety analyses, and 587 in immunological analyses. The frequency of grade 3-4 reactions was similar between arms (half-dose: 4/299 [1.3%]; full-dose: 6/299 [2.0%]). Across all severity grades, half-dose recipients reported fewer local and systemic reactions (60% versus 72% and 25% versus 32%, respectively). Seroresponse was 84.7% (250/295) and 86.6% (253/292) in the half-dose and full-dose arms, respectively (Difference: -2.8%; 95% CI -7.7, 2.1). Geometric mean IgG titres were similar in those receiving full and half-dose boosters for the ChAdOx1 and BBIBP-CorV primed groups, but lower in the half-dose arm in Gam-COVID-Vac-primed participants (GMR: 0.71; 95% CI 0.54, 0.93). Interpretation: Half-dose BNT162b2 boosting elicited an immune response that was non-inferior to a full-dose, with fewer reactions, in adults primed with ChAdOx1 nCov-19 or BBIBP-CorV. Half-dose boosting may not be suitable in adults primed with Gam-COVID-Vac. Half-dose BNT162b2 boosting may be considered in populations primed with ChAdOx1 nCov-19 or BBIBP-CorV. Funding: Coalition for Epidemic Preparedness Innovations (CEPI).
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