ReviewVaccines2022
Percentage of Asymptomatic Infections among SARS-CoV-2 Omicron Variant-Positive Individuals: A Systematic Review and Meta-Analysis.
Review in Vaccines, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 84 papers, 3 of them syntheses that pooled it.
What it found
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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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
84 citing papers in PubMed, 3 syntheses or guidelines pooled it, 161 citations in OpenAlex.
- The Asymptomatic Proportion of SARS-CoV-2 Omicron Variant Infections in Households: A Systematic Review.Influenza and other respiratory viruses · 2024Pooled it
- Evidence linking COVID-19 and the health/well-being of children and adolescents: an umbrella review.BMC medicine · 2024Pooled it
- How are countries responding differently to COVID-19: a systematic review of guidelines on isolation measures.Frontiers in public health · 2023Pooled it
- Systematic prediction of spatiotemporal transmission of potential respiratory pandemics in China.Infectious Disease Modelling · 2026Article
- Comment on "The association between COVID-19 and incident gestational diabetes: A population-based case-control study of the National Health Insurance Research Database in Taiwan".Journal of diabetes investigation · 2026Article
- Exploratory longitudinal cohort study of modest bilirubin-driven biochemical liver alterations after SARS-CoV-2 infection in a selected subgroup of patients with Wilson's disease and liver cirrhosis.BMC gastroenterology · 2026Article
- XBB 1.5 monovalent booster vaccination stimulates oral mucosal and systemic immune responses in healthy adults.Vaccine · 2026Article
- Quantifying SARS-CoV-2 Omicron variant spread and the impact of non-pharmaceutical interventions in Newfoundland and Labrador, Canada.PLoS computational biology · 2026Article
- Article
- Article
- Transcriptomic profiling reveals immune signatures associated with potential COVID-19 susceptibility and a predictive framework in a Chinese cohort.Frontiers in immunology · 2026Article
- Epidemiological Trends of COVID-19 Infection and Symptom Incidence in China Following the Adjustment of Zero-COVID Policy: A Prospective, Community-Based Cohort Study.Transboundary and emerging diseases · 2026Article
- Estimation of undetected asymptomatic infections of COVID-19: a mathematical modeling approach.Scientific reports · 2025Article
- Observational
- Article
- Long-Term Sewage Survey of SARS-CoV-2, Influenza A and Respiratory Syncytial Virus (RSV), and Correlation to Human Cases in a City with One Million Inhabitants.Microorganisms · 2025Article
- SARS-CoV-2 secondary attack rates and risks for transmission among agricultural workers and their households in Guatemala, 2022-2023.IJID regions · 2025Article
- Review
- Machine learning approaches to dissect hybrid and vaccine-induced immunity.Communications medicine · 2025Article
- The COVID-19 pandemic in children and young people during 2022-24: what new did we learn?Journal of global health · 2025Article
24 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors at 1 institution in 1 country.
Funding
Abstract
Background: Asymptomatic infections are potential sources of transmission for coronavirus disease 2019, especially during the epidemic of the SARS-CoV-2 Omicron variant. We aimed to assess the percentage of asymptomatic infections among SARS-CoV-2 Omicron variant-positive individuals detected by gene sequencing or specific polymerase chain reaction (PCR). Methods: We searched PubMed, EMBASE, and Web of Science from 26 November 2021 to 13 April 2022. This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered with PROSPERO (CRD42022327894). Three researchers independently extracted data and two researchers assessed quality using pre-specified criteria. The pooled percentage with 95% confidence interval (CI) of asymptomatic infections of SARS-CoV-2 Omicron was estimated using random-effects models. Results: Our meta-analysis included eight eligible studies, covering 7640 Omicron variant-positive individuals with 2190 asymptomatic infections. The pooled percentage of asymptomatic infections was 32.40% (95% CI: 25.30−39.51%) among SARS-CoV-2 Omicron variant-positive individuals, which was higher in the population in developing countries (38.93%; 95% CI: 19.75−58.11%), with vaccine coverage ≥ 80% (35.93%; 95% CI: 25.36−46.51%), with a travel history (40.05%; 95% CI: 7.59−72.51%), community infection (37.97%; 95% CI: 10.07−65.87%), and with a median age < 20 years (43.75%; 95% CI: 38.45−49.05%). Conclusion: In this systematic review and meta-analysis, the pooled percentage of asymptomatic infections was 32.40% among SARS-CoV-2 Omicron variant-positive individuals. The people who were vaccinated, young (median age < 20 years), had a travel history, and were infected outside of a clinical setting (community infection) had higher percentages of asymptomatic infections. Screening is required to prevent clustered epidemics or sustained community transmission caused by asymptomatic infections of Omicron variants, especially for countries and regions that have successfully controlled SARS-CoV-2.
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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.