Evidence map›Paper›PMID 41021660›Full record

ArticleClinical infectious diseases : an official publication of the Infectious Diseases Society of America2026

Effectiveness of COVID-19 Vaccination and Prior Infections to Reduce Long COVID Risk During the Pre-Omicron and Omicron Periods.

Sara Carazo, Jonathan Phimmasone, Danuta M Skowronski, Katia Giguère, Manale Ouakki, Denis Talbot, Charles-Antoine Guay, Chantal Sauvageau, Nicholas Brousseau, Gaston De Serres

Abstract read
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In one paragraph

Article in Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.

0numbers the graph read from it
0cells of the map it votes in
5citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from 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.

2 · The registry

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.

3 · Its place in the literature

Who cites it

5 citing papers in PubMed.

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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

10 authors.

Sara CarazoSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.ORCID 0000-0003-0711-6703
Jonathan PhimmasoneSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.
Danuta M SkowronskiCommunicable Diseases and Immunization Services, BC Centre for Disease Control, Vancouver, BC, Canada.
Katia GiguèreSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.
Manale OuakkiSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.ORCID 0000-0002-3068-4373
Denis TalbotResearch Center, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Quebec City, QC, Canada.ORCID 0000-0003-0431-3314
Charles-Antoine GuaySocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.
Chantal SauvageauSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.ORCID 0000-0002-4300-1658
Nicholas BrousseauSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.ORCID 0000-0001-6042-3177
Gaston De SerresSocial and Preventive Medicine Department, Faculty of Medicine, Laval University, Quebec city, QC, Canada.ORCID 0000-0002-1592-5167

Funding

Fonds de recherche du QuébecMinistère de la Santé et des Services Sociaux du QuébecPublic Health Agency of Canada
6 · The paper itself

Abstract

backgroundWe estimated vaccine effectiveness (VE) against COVID-19 and long COVID during pre-Omicron and Omicron periods, by number of doses and prior infection history.

methodsWe combined survey information from a cohort of healthcare workers in Quebec, Canada, with immunization registry and laboratory administrative data. We defined COVID-19 cases as symptomatic laboratory-confirmed infections and long COVID as self-reported symptoms persisting ≥12 weeks. We assessed VE against COVID-19 and long COVID, stratified by infection history, using a test-negative design where vaccinated participants were compared to unvaccinated participants during the pre-Omicron period or to those twice vaccinated ≥6 months before laboratory testing during the Omicron period.

resultsAnalyses included 8230 COVID-19 participants and 43 361 tested specimens. During the pre-Omicron period, 1- and 2-dose VE was 75% (95% CI: 64-83) and 95% (95% CI: 84-98) against COVID-19, respectively, and 91% (95% CI: 79-96) and 87% (95% CI: 22-98) against long COVID, respectively. During the Omicron period, booster dose VE was 41% (95% CI: 34-47) against COVID-19 and 57% (95% CI: 46-66) against long COVID, waning by 6 months. Hybrid VE in vaccinated and previously infected individuals ranged from 81% (95% CI: 38-94) to 92% (95% CI: 87-95) regardless of number of doses, prior infecting variant or median time since last immunological event up to 9 months.

conclusionsCOVID-19 vaccination prevented long COVID during the pre-Omicron period and reduced the risk by more than half post-Omicron. With most of the population by now both vaccinated and infected, repeated booster doses may add little incremental value against long COVID, an observation with important public health, immunization program, and cost implications.

Indexed as

COVID-19COVID-19 VaccinesVaccine EfficacyAdultAgedFemaleHealth PersonnelHumansMaleMiddle AgedQuebecSARS-CoV-2VaccinationYoung AdultCOVID-19 Vaccineshybrid immunitylong COVIDSARS-CoV-2vaccine effectiveness

Identifiers

PMID41021660
PMCPMC13016730

What OpenQuestion holds

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LicenceCC BY-NC-ND
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Registered trials

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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.