SynthesisHuman vaccines & immunotherapeutics2023
Effectiveness of the pre-Omicron COVID-19 vaccines against Omicron in reducing infection, hospitalization, severity, and mortality compared to Delta and other variants: A systematic review.
Synthesis in Human vaccines & immunotherapeutics, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 39 papers, 3 of them syntheses 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
39 citing papers in PubMed, 3 syntheses or guidelines pooled it.
- Long-Term Complications of Multisystem Inflammatory Syndrome in Children and Adults Post-COVID-19: A Systematic Review.International journal of molecular sciences · 2025Pooled it
- The relative prevalence of the Omicron variant within SARS-CoV-2 infected cohorts in different countries: A systematic review.Human vaccines & immunotherapeutics · 2023Pooled it
- Role of previous infection with SARS-CoV-2 in protecting against omicron reinfections and severe complications of COVID-19 compared to pre-omicron variants: a systematic review.BMC infectious diseases · 2023Pooled it
- Trial
- COVID-19 vaccine booster uptake among healthcare workers in Bangladesh: predictors, challenges, and lessons from a low-income setting.Tropical medicine and health · 2026Article
- The role of vaccination, underlying health conditions, and working in healthcare in the socioeconomic disparities in COVID-19 hospitalization: a mediation analysis using interventional effect models.BMC infectious diseases · 2026Article
- Heterologous betacoronavirus spike immunization in nonhuman primates elicits cross-reactive antibodies that neutralize both sarbeco- and merbecoviruses.bioRxiv : the preprint server for biology · 2026Article
- Heterologous mucosal vaccine boosting enhances mucosal and systemic immunity by distinct mechanisms.The Journal of experimental medicine · 2026Article
- COVID-19 convalescent plasma safety and efficacy analysis for biologics license application approval.Expert review of anti-infective therapy · 2026Review
- mRNA COVID-19 Vaccine Effectiveness Against Severe Outcomes Among Adults Hospitalized with COVID-19 from May 2021 to January 2023.Vaccines · 2025Article
- Heterogeneous Evolution Among SARS-CoV-2 Genes and Variants of Concern.Journal of medical virology · 2025Article
- SARS-CoV-2 breakthrough infection during pregnancy preferentially elicits IgG4 response and enhanced placental-transfer.Vaccine · 2025Article
- Determining population-specific risk factors for COVID-19 susceptibility and severity to inform future individual-level integrated risk scoring.BMC infectious diseases · 2025Article
- Metabolic features of patients with repeated Omicron infections highlight new targets for therapeutic intervention.Scientific reports · 2025Article
- Trans amplifying mRNA vaccine expressing consensus spike elicits broad neutralization of SARS CoV 2 variants.NPJ vaccines · 2025Article
- Effectiveness of a single COVID-19 mRNA vaccine dose in individuals with prior SARS-CoV-2 infection: a systematic review.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
- Article
- Physical Health and Mental Fatigue Disability Associated with Long COVID: Baseline Results from a US Nationwide Cohort.The American journal of medicine · 2025Article
- Early symptoms and 12-week follow-up of pediatric omicron infections during the Beijing outbreak.Frontiers in pediatrics · 2025Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
27 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Despite widespread mass rollout programs, the rapid spread of the SARS-CoV-2 Omicron variant called into question the effectiveness of the existing vaccines against infection, hospitalization, severity, and mortality compared to previous variants. This systematic review summarizes and compares the effectiveness of the COVID-19 vaccines, with respect to the above outcomes in adults, children, and adolescents. A comprehensive literature search was undertaken on several databases. Only 51 studies met our inclusion criteria, revealing that the protection from primary vaccination against Omicron infection is inferior to protection against Delta and Alpha infections and wanes faster over time. However, mRNA vaccine boosters were reported to reestablish effectiveness, although to a lower extent against Omicron. Nonetheless, primary vaccination was shown to preserve strong protection against Omicron-associated hospitalization, severity, and death, even months after last dose. However, boosters provide more robust and longer-lasting protection against hospitalizations due to Omicron as compared to only primary series.
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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.