Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia
The Lancet·
- DOI
- 10.1016/s0140-6736(21)00234-8
- PMID
- 33545094
- PMCID
- PMC7852454
- OpenAlex
- W3127329393
- Study type
- Randomised controlled trial
- Publisher
- Elsevier BV
- Article type
- journal-article
- Integrity
- current
Why this research matters now
This interim analysis provides evidence from a large-scale phase 3 trial supporting the efficacy and tolerability of a two-dose adenovirus-vectored COVID-19 vaccine in adults.
Structured evidence summary
Research question
The study aimed to evaluate the preliminary efficacy and safety of Gam-COVID-Vac (Sputnik V), a heterologous recombinant adenovirus-based COVID-19 vaccine, in a phase 3 randomized controlled trial.
Study design
A randomized, double-blind, placebo-controlled phase 3 trial was conducted across 25 hospitals and polyclinics in Moscow, Russia, using a prime-boost regimen with rAd26 and rAd5 vectors carrying the SARS-CoV-2 glycoprotein S gene, administered 21 days apart.
Population and setting
The trial enrolled 21,977 adults aged at least 18 years who had negative SARS-CoV-2 PCR and antibody tests, no recent infectious diseases, and no other vaccinations within 30 days prior to enrollment.
Main findings
From day 21 after the first dose, COVID-19 was confirmed in 16 (0.1%) of 14,964 vaccine recipients versus 62 (1.3%) of 4,902 placebo recipients, yielding a vaccine efficacy of 91.6% (95% CI 85.6-95.2). Most adverse events were grade 1 (94.0%); serious adverse events occurred in 0.3% of vaccine and 0.4% of placebo participants, with none judged vaccine-related.
Public-health relevance
This interim analysis provides evidence from a large-scale phase 3 trial supporting the efficacy and tolerability of a two-dose adenovirus-vectored COVID-19 vaccine in adults.
Important limitations
This summary is limited to the supplied single-article abstract and metadata; the original paper is required for decision-grade interpretation. Key limitations include that these are interim results from a single-country trial, the primary outcome excluded protocol violators, and long-term safety and efficacy data were not yet available at the time of analysis.
GIDS interpretation
This peer-reviewed randomized controlled trial published in The Lancet provides clinical trial evidence regarding a COVID-19 vaccine candidate. As a phase 3 efficacy trial, it informs the evidence base for vaccine development but does not constitute surveillance data or confirm effectiveness in real-world settings.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 13 auditable classifier relationships to diseases, places, topics, and study design.