ArticleThe Lancet regional health. Western Pacific2023
Efficacy and effectiveness of inactivated vaccines against symptomatic COVID-19, severe COVID-19, and COVID-19 clinical outcomes in the general population: a systematic review and meta-analysis.
Article in The Lancet regional health. Western Pacific, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
17 citing papers in PubMed, 1 synthesis or guideline pooled it, 22 citations in OpenAlex.
- How well do different COVID-19 vaccines protect against different viral variants? A systematic review and meta-analysis.Transactions of the Royal Society of Tropical Medicine and Hygiene · 2025Pooled it
- Characteristics of COVID-19 cases and factors associated with disease severity in Lao People's Democratic Republic: a nationwide study.BMC infectious diseases · 2026Observational
- COVID-19 Vaccination and Health Outcomes Among Adults With an Intellectual Disability in British Columbia, Canada.Journal of intellectual disability research : JIDR · 2026Article
- Impact of COVID-19 vaccination and vaccine type on morbidity and mortality in hospitalized patients: a retrospective cohort study in Egypt.Frontiers in microbiology · 2026Article
- Article
- Review
- Factors Influencing COVID-19 Viral Clearance: Implications for Vaccination and Antiviral Therapy.Infection and drug resistance · 2025Article
- Article
- Effect of bluetongue serotype 3 vaccines on probability of viremia and NSAID usage in Dutch dairy cattle herds.Frontiers in veterinary science · 2025Article
- A systematic review and modelling insights of factors impacting measles vaccine effectiveness, efficacy and immunogenicity.Discover viruses · 2025Review
- Factors associated with COVID-19 in-hospital death and COVID-19 vaccine effectiveness against COVID-19 hospitalization in the Philippines during pre-omicron and omicron period: A case-control study (MOTIVATE-P study).Epidemiology and infection · 2024Article
- COVID-19 vaccination and major cardiovascular and haematological adverse events in Abu Dhabi: retrospective cohort study.Nature communications · 2024Article
- Shift in SARS-CoV-2 variants of concern from Delta to Omicron was associated with reduced hospitalizations, increased risk of breakthrough infections but lesser disease severity.Journal of infection and public health · 2024Article
- Conservation of HLA Spike Protein Epitopes Supports T Cell Cross-Protection in SARS-CoV-2 Vaccinated Individuals against the Potentially Zoonotic Coronavirus Khosta-2.International journal of molecular sciences · 2024Article
- Inactivated COVID-19 vaccination and SARS-CoV-2 infection among Chinese adults in the "living with COVID" era.Heliyon · 2024Article
- Biases in COVID-19 vaccine effectiveness studies using cohort design.Frontiers in medicine · 2024Review
- Two centuries of vaccination: historical and conceptual approach and future perspectives.Frontiers in public health · 2023Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
10 authors at 4 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: Inactivated, whole-virion vaccines have been used extensively in the SARS-CoV-2 pandemic. Its efficacy and effectiveness across regions have not been systematically evaluated. Efficacy refers to how well a vaccine performs in a controlled environment. Effectiveness refers to how well it performs in real world settings. Methods: This systematic review and meta-analysis reviewed published, peer-reviewed evidence on all WHO-approved inactivated vaccines and evaluated their efficacy and effectiveness against SARS-CoV-2 infection, symptomatic infection, severe clinical outcomes, and severe COVID-19. We searched Pubmed (including MEDLINE), EMBASE (via OVID), Web of Science Core Collection, Web of Science Chinese Science Citation Database, and Clinicaltrials.gov. Findings: The final pool included 28 studies representing over 32 million individuals reporting efficacy or effectiveness estimates of complete vaccination using any approved inactivated vaccine between January 1, 2019 and June 27, 2022. Evidence was found for efficacy and effectiveness against symptomatic infection (OR 0.21, 95% CI 0.16-0.27, I Interpretation: This study showed evidence of efficacy and effectiveness of inactivated vaccines for all outcomes, although inconsistent reporting of key study parameters, high heterogeneity of observational studies, and the small number of studies of particular designs for most outcomes undermined the reliability of the findings. Findings highlight the need for additional research to address these limitations so that more definitive conclusions can be drawn to inform SARS-CoV-2 vaccine development and vaccination policies. Funding: Health and Medical Research Fund on COVID-19, Health Bureau of the Government of the Hong Kong SAR.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.