Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern: A 14-month observational study using surveillance data

We evaluated measures to protect healthcare workers (HCWs) in Vancouver, Canada, where variants of concern (VOC) went from 92% in mid-May. Canada has amongst the longest periods between vaccine doses worldwide, despite Vancouver having the highest P.1 variant rate outside Brazil. With surveillance d...

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Bibliographic Details
Published in:PloS one 2021-07, Vol.16 (7), p.e0254920-e0254920
Main Authors: Yassi, Annalee, Grant, Jennifer M, Lockhart, Karen, Barker, Stephen, Sprague, Stacy, Okpani, Arnold I, Wong, Titus, Daly, Patricia, Henderson, William, Lubin, Stan, Kim Sing, Chad
Format: Article
Language:English
Subjects:
2019-nCoV Vaccine mRNA-1273
Biology and Life Sciences
Canada
Coronaviruses
COVID-19 - epidemiology
COVID-19 - prevention & control
COVID-19 - virology
COVID-19 diagnostic tests
COVID-19 vaccines
COVID-19 Vaccines - administration & dosage
Disease transmission
Dosage
Drug dosages
Emergency medical care
Evaluation
Health care
Health Personnel - statistics & numerical data
Health risks
Health surveillance
Humans
Immunization
Infection control
Infection Control - statistics & numerical data
Infections
Jurisdiction
Laboratories
Masks
Medical personnel
Medical supplies
Medicine
Medicine and Health Sciences
Methods
mRNA
Observational studies
Occupational health
Occupational Health - statistics & numerical data
Occupational safety
Pandemics
Pathology
Patient safety
People and Places
Personal health
Personal protective equipment
Polymorphism, Genetic
Population
Public health
Public health administration
SARS-CoV-2 - genetics
Severe acute respiratory syndrome
Severe acute respiratory syndrome coronavirus 2
Vaccination
Vaccination - statistics & numerical data
Vaccine efficacy
Vaccines
Viral diseases
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Summary:We evaluated measures to protect healthcare workers (HCWs) in Vancouver, Canada, where variants of concern (VOC) went from 92% in mid-May. Canada has amongst the longest periods between vaccine doses worldwide, despite Vancouver having the highest P.1 variant rate outside Brazil. With surveillance data since the pandemic began, we tracked laboratory-confirmed SARS-CoV-2 infections, positivity rates, and vaccine uptake in all 25,558 HCWs in Vancouver Coastal Health, by occupation and subsector, and compared to the general population. Cox regression modelling adjusted for age and calendar-time calculated vaccine effectiveness (VE) against SARS-CoV-2 in fully vaccinated (≥ 7 days post-second dose), partially vaccinated infection (after 14 days) and unvaccinated HCWs; we also compared with unvaccinated community members of the same age-range. Only 3.3% of our HCWs became infected, mirroring community rates, with peak positivity of 9.1%, compared to 11.8% in the community. As vaccine coverage increased, SARS-CoV-2 infections declined significantly in HCWs, despite a surge with predominantly VOC; unvaccinated HCWs had an infection rate of 1.3/10,000 person-days compared to 0.89 for HCWs post first dose, and 0.30 for fully vaccinated HCWs. VE compared to unvaccinated HCWs was 37.2% (95% CI: 16.6-52.7%) 14 days post-first dose, 79.2% (CI: 64.6-87.8%) 7 days post-second dose; one dose provided significant protection against infection until at least day 42. Compared with community infection rates, VE after one dose was 54.7% (CI: 44.8-62.9%); and 84.8% (CI: 75.2-90.7%) when fully vaccinated. Rigorous droplet-contact precautions with N95s for aerosol-generating procedures are effective in preventing occupational infection in HCWs, with one dose of mRNA vaccination further reducing infection risk despite VOC and transmissibility concerns. Delaying second doses to allow more widespread vaccination against severe disease, with strict public health, occupational health and infection control measures, has been effective in protecting the healthcare workforce.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0254920