Incidence and factors associated with SARS-CoV-2 infection and re-infection among people experiencing homelessness in Toronto, Canada: A prospective cohort study
Bibliographic record
Abstract
People experiencing homelessness are at elevated risk of SARS-CoV-2 infection, yet estimates generally exclude re-infections and rely on data sources affected by testing policies or study timing. In this prospective cohort study, we report incidence of SARS-CoV-2 infection and re-infections over time using a combination of community-based and study-administered testing, and assessed individual and housing-related factors associated with new infection. Individuals experiencing homelessness were randomly selected from 62 sites across Toronto, Canada, between June and September 2021. Participants provided detailed surveys and biological samples to test for SARS-CoV-2 (by RT-PCR and ELISA) every three months for one year. Self-reported data were verified and augmented through linkage to health administrative databases. Among 640 participants who completed 2,401 interviews, we identified 613 SARS-CoV-2 infection events, representing an incidence rate of 35.3 infections/100-person years (95% CI 31.6-39.4) prior to the onset of Omicron and 97.2 infections/100 person-years (95% CI 86.8-108.8) after Omicron. Nearly 30% (n = 182) of these events were re-infections. In multivariable models, post-Omicron interviews (adjusted rate ratio [aRR] 3.54 [95% CI 3.12-4.02]), history of prior COVID-19 infection (1 infection aRR 2.55 [95% CI 2.29-2.83]; 2 + infections aRR 2.28 [95% CI 1.80-2.89]) and residing in high- or moderate-exposure risk (congregate and shared) housing settings (high-exposure aRR 1.74 [95% CI 1.43-2.11]; moderate-exposure aRR 1.39 [1.15-1.68]) were most significantly associated with new infection. Our findings highlight that existing reports significantly underestimate SARS-CoV-2 infection burden among people experiencing homelessness, but confirms previously reported factors associated with infection, including congregate and shared housing settings. Reducing reliance on overcrowded emergency housing is necessary to reduce infection incidence in this population as well as associated inequities in downstream acute and chronic complications.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".