ArticleBMJ (Clinical research ed.)2022
Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study.
Article in BMJ (Clinical research ed.), 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 94 papers, 5 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
94 citing papers in PubMed, 5 syntheses or guidelines pooled it, 148 citations in OpenAlex.
- Comparative Effectiveness of mRNA-1273 and BNT162b2 COVID-19 Vaccines Among Adults with Underlying Medical Conditions: Systematic Literature Review and Pairwise Meta-Analysis Using GRADE.Advances in therapy · 2025Pooled it
- New variants of COVID-19 (XBB.1.5 and XBB.1.16, the "Arcturus"): A review of highly questioned concerns, a brief comparison between different peaks in the COVID-19 pandemic, with a focused systematic review on expert recommendations for prevention, vaccination, and treatment measures in the general population and at-risk groups.Immunity, inflammation and disease · 2024Pooled it
- Pooled it
- Humoral response after a fourth dose of SARS-CoV-2 vaccine in immunocompromised patients. Results of a systematic review.Frontiers in public health · 2023Pooled it
- Effectiveness of SARS-CoV-2 vaccines against Omicron infection and severe events: a systematic review and meta-analysis of test-negative design studies.Frontiers in public health · 2023Pooled it
- Safety and immunogenicity of Ad5-nCoV immunization after three-dose priming with inactivated SARS-CoV-2 vaccine in Chinese adults.Nature communications · 2023Trial
- Persistence of immune responses after heterologous and homologous third COVID-19 vaccine dose schedules in the UK: eight-month analyses of the COV-BOOST trial.The Journal of infection · 2023Trial
- Study of efficacy and antibody duration to fourth-dose booster of Ad5-nCoV or inactivated SARS-CoV-2 vaccine in Chinese adults: a prospective cohort study.Frontiers in immunology · 2023Trial
- Booster dose of COVID-19 vaccine and its effectiveness against post COVID-19 condition in individuals with pre-existing immunity: a sequential propensity score-matched cohort study.EClinicalMedicine · 2026Article
- 2024-2025 COVID-19 Vaccine and Major Adverse Cardiovascular Events Among US Veterans.JAMA internal medicine · 2026Article
- Evaluation of glucose metabolism, endocrine, and renal functions following vaccination in post-COVID-19 individuals: a longitudinal retrospective single-center cohort study.BMC infectious diseases · 2025Article
- Review
- The protective effect of emergency fourth-dose vaccination issued to county-level hospital nurses against the Omicron infection peak: evidence from China.BMC nursing · 2025Article
- COVID-19 Vaccine Uptake Rates and Associated Factors in Racially Diverse Parents in Canada: The Threat From Conspiracy Beliefs and Racial Discrimination.Journal of medical virology · 2025Article
- Cracking the code of a correlate of protection against SARS-CoV-2 breakthrough infection in cancer patients.Scientific reports · 2025Article
- Measures to Prevent and Control COVID-19 in Skilled Nursing Facilities: A Scoping Review.JAMA health forum · 2025Article
- Omission of alcohol skin cleansing and risk of adverse events in long-term care residents undergoing COVID-19 vaccination: A cohort study.Human vaccines & immunotherapeutics · 2024Article
- mRNA vaccines encoding membrane-anchored RBDs of SARS-CoV-2 mutants induce strong humoral responses and can overcome immune imprinting.Molecular therapy. Methods & clinical development · 2024Article
- The Effectiveness of COVID-19 Vaccines During the Pre-Omicron and Omicron Periods: A Retrospective Test-Negative Case-Control Study.Vaccines · 2024Article
- Post-COVID-19 condition symptoms among emergency department patients tested for SARS-CoV-2 infection.Nature communications · 2024Article
34 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 4 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectivesTo estimate the marginal effectiveness of a fourth versus third dose and the vaccine effectiveness of mRNA covid-19 vaccines BNT162b2 and mRNA-1273 against any infection, symptomatic infection, and severe outcomes (hospital admission or death) related to the omicron variant.
designTest negative design.
settingLong term care facilities in Ontario, Canada, 30 December 2021 to 27 April 2022.
participantsAfter exclusions, 61 344 residents aged 60 years or older across 626 long term care facilities in Ontario, Canada who were tested for SARS-CoV-2 were included.
main outcome measuresLaboratory confirmed omicron SARS-CoV-2 infection (any and symptomatic) by reverse transcription polymerase chain reaction (RT-PCR), and hospital admission or death. Multivariable logistic regression was used to estimate marginal effectiveness (four versus three doses) and vaccine effectiveness (two, three, or four doses versus no doses) while adjusting for personal characteristics, comorbidities, week of test, and previous positive SARS-CoV-2 test result more than 90 days previously.
results13 654 residents who tested positive for omicron SARS-CoV-2 infection and 205 862 test negative controls were included. The marginal effectiveness of a fourth dose (95% of vaccine recipients received mRNA-1273 as the fourth dose) seven days or more after vaccination versus a third dose received 84 or more days previously was 19% (95% confidence interval 12% to 26%) against infection, 31% (20% to 41%) against symptomatic infection, and 40% (24% to 52%) against severe outcomes. Vaccine effectiveness in vaccine recipients (compared with unvaccinated) increased with each additional dose, and for a fourth dose was 49% (95% confidence interval 43% to 54%) against infection, 69% (61% to 76%) against symptomatic infection, and 86% (81% to 90%) against severe outcomes.
conclusionsThe findings suggest that compared with a third dose of mRNA covid-19 vaccine, a fourth dose improved protection against infection, symptomatic infection, and severe outcomes among long term care residents during an omicron dominant period. A fourth vaccine dose was associated with strong protection against severe outcomes in vaccinated residents compared with unvaccinated residents, although the duration of protection remains unknown.
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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.