SCORE: Serologic evidence of COVID-19 and social and occupational contacts in healthcare workers in long-term care and acute care facilities in Southeastern Ontario (SCORE)
Bibliographic record
Abstract
INTRODUCTION: We established a longitudinal cohort of healthcare workers (HCWs) in an acute care hospital (ACH) and four long-term care homes (LTCHs) in Ontario, Canada, to follow the incidence of SARS-CoV-2 infection, humoral immune response to infection and/or vaccination, and determinants of infection risk. Here, we 1) describe the cohort regarding the distribution of main exposures, outcomes and serologic assays, 2) describe the unadjusted incidence of SARS-CoV-2 infection risk in the overall population, and 3) summarize the analysis and its pertinence. METHODS AND PARTICIPANTS: HCWs were recruited between November 24, 2020, and July 24, 2021. They completed a baseline survey, monthly surveillance for 9-12 months, a post-Omicron-wave survey, and provided blood samples for anti-SARS-CoV-2 antibody measurements. We collected data on host-related (humoral response to vaccines and SARS-CoV-2 infection) and environmental factors (social contact history and occupational, household and community conditions). Descriptive analysis by setting, comparison of distributions, and unadjusted survival analysis were performed. RESULTS: In total, 143 HCWs from the ACH and 57 from LTCHs had complete data, and 72% were followed until September 2022. Nearly 60% of the sample consisted of nurses, nurse assistants and personal support workers. Survival analysis showed that the risk of infection was bimodal, with low risk throughout the study period until the first Omicron wave. ACH HCWs had a higher risk of infection during the Omicron waves than during the preceding waves (Odds Ratio = 7.64; CI95%: 4.24-13.7), while LTCH HCWs at high-risk facilities experienced a similar risk of infection before and during the Omicron waves (OR = 1.76; CI95%: 0.63-4.9). During the Omicron waves, the use of protective equipment by HCWs working with institutional COVID-19 cases increased, but the use of community protective measures diminished. Household infections reported by participating HCWs also increased during the Omicron waves compared to previous waves. Immunoglobulin G (IgG) antibody levels increased over two time periods, (Pre vs Post- Omicron) likely due to the immune response to high levels of both vaccination and SARS-CoV-2 infections. DISCUSSION: We observed a low incidence of COVID-19 until the onset of the Omicron waves, which highlights the drastic impact of this Variants of Concern (VOC) on transmission and the importance of infectious agent characteristics. Our analysis indicated a ninefold increased risk of infection compared to that in earlier pandemic periods. Further analysis will allow the estimation of 1) the risk factors for SARS-CoV-2 infection at the community, household and healthcare facility levels, 2) the relationship between humoral responses and SARS-CoV-2 infection/vaccination, and 3) the role of social contact in work, household and community settings in the risk of infection.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".