Effectiveness and safety of SARS-CoV-2 vaccine in real-world studies: a systematic review and meta-analysis
Infectious Diseases of Poverty·
- DOI
- 10.1186/s40249-021-00915-3
- PMID
- 34776011
- PMCID
- PMC8590867
- OpenAlex
- W3213552396
- Study type
- Systematic review
- Publisher
- Springer Science and Business Media LLC
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The findings support accelerating vaccination and improving coverage as a critical strategy to reduce COVID-19 deaths, severe cases, symptomatic infections, and transmission in the context of ongoing variant emergence.
Structured evidence summary
Research question
This systematic review and meta-analysis evaluated the real-world effectiveness and safety of COVID-19 vaccines, including their performance against emerging variants.
Study design
The authors conducted a systematic review and meta-analysis of observational studies examining COVID-19 vaccine effectiveness and safety. They searched three databases through July 2021 and used random-effects or fixed-effects models to pool vaccine effectiveness estimates and adverse event incidence rates.
Population and setting
The review included 58 observational studies of people who received SARS-CoV-2 vaccines in real-world settings across multiple countries.
Main findings
A single vaccine dose showed 41% effectiveness against infection, 52% against symptomatic disease, 66% against hospitalization, and 53% against death. Two doses demonstrated 85% effectiveness against infection, 97% against symptomatic disease, 93% against hospitalization, and 95% against death. Variant-specific effectiveness was 85% for Alpha, 75% for Beta, 54% for Gamma, and 74% for Delta. The pooled adverse event incidence was 1.5%, with severe adverse events at 0.4 per 10,000 and death at 0.1 per 10,000.
Public-health relevance
The findings support accelerating vaccination and improving coverage as a critical strategy to reduce COVID-19 deaths, severe cases, symptomatic infections, and transmission in the context of ongoing variant emergence.
Important limitations
This summary is limited to the supplied single-article abstract and metadata. The abstract does not explicitly state study-level limitations such as heterogeneity across included studies, differences in vaccine types or regional vaccination programs, or time-varying effectiveness. Access to the full paper is required for decision-grade interpretation.
GIDS interpretation
The classifier links associate this article with COVID-19, SARS, vaccination topics including vaccine effectiveness and safety, outbreak investigation, and surveillance. These links reflect the research content and support discoverability within disease surveillance literature collections. They do not indicate that this meta-analysis was triggered by or confirms any live surveillance signal.
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 12 auditable classifier relationships to diseases, places, topics, and study design.