Rates of COVID-19-Associated Hospitalization in Immunocompromised Individuals in Omicron-era: A Population-Based Observational Study Using Surveillance Data in British Columbia, Canada (preprint)

Background: People with immune dysfunction have a higher risk for severe COVID-19 outcomes. Omicron variant is associated with a lower rate of hospitalization but higher vaccine escape. This population-based study quantifies COVID-19 hospitalization rate in the Omicron-dominant era among vaccinated people with immune dysfunction, identified as clinically extremely vulnerable (CEV) population before COVID-19 treatment was widely offered. Methods: All COVID-19 cases were reported to the British Columbia Centre for Disease Control (BCCDC) between January 7, 2022 and March 14, 2022. Case and population hospitalization rates were estimated across CEV status, age groups and vaccination status. Cumulative rates of hospitalizations for the study period were also compared between CEV and non-CEV individuals matched by sex, age group, region, and vaccination characteristics. Findings: A total of 5,591 COVID-19 reported cases and 1,153 hospitalizations among CEV individuals were included. A third vaccine dose with mRNA vaccine offered additional protection against severe illness in CEV individuals. Vaccinated CEV population still had a significantly higher breakthrough hospitalization rate compared with non-CEV individuals. Interpretation: CEV population remains a higher risk group and may benefit from additional booster doses and pharmacotherapy. Funding: BC Centre for Disease Control and Provincial Health Services Authority

COVID-19 infection and vaccination rates in healthcare workers in British Columbia, Canada: A Longitudinal Urban versus Rural Analysis of the Impact of the Vaccine Mandate (preprint)

Purpose: Healthcare workers (HCWs) play a critical role in responding to the COVID-19 pandemic. Early in the pandemic, urban centres were hit hardest globally; rural areas gradually became more impacted. We compared COVID-19 infection and vaccine uptake in HCWs living in urban versus rural locations within, and between, two health authorities in British Columbia (BC), Canada. We also analyzed the impact of a vaccine mandate for HCWs. Methods: We tracked laboratory-confirmed SARS-CoV-2 infections, positivity rates, and vaccine uptake in 29,021 HCWs in Interior Health (IH) and 24,634 HCWs in Vancouver Coastal Health (VCH), by occupation, age, and home location, comparing to the general population in that region. We then evaluated the impact of infection rates as well as the mandate on vaccination uptake. Results: By October 27, 2021, the date that unvaccinated HCWs were prohibited from providing healthcare, only 1.6% in VCH yet 6.5% in IH remained unvaccinated. Rural workers in both areas had significantly higher unvaccinated rates compared with urban dwellers. Over 1,800 workers, comprising 6.4% of rural HCWs and 3.3% of urban HCWs, remained unvaccinated and set to be terminated from their employment. While the mandate prompted a significant increase in second doses, the impact on the unvaccinated was less clear. Conclusions: As rural areas often suffer from under-staffing, loss of HCWs could have serious impacts on healthcare provision as well as on the livelihoods of unvaccinated HCWs. Greater efforts are needed to understand how to better address the drivers of rural-related vaccine hesitancy as the pandemic continues.

A mixed-methods study of risk factors and experiences of healthcare workers tested for the novel coronavirus in Canada (preprint)

Objectives We aimed to investigate the contribution of occupational and non-work-related factors to the risk of novel coronavirus (SARS-CoV-2) infection among healthcare workers (HCWs) in Vancouver Coastal Health, British Columbia, Canada. We also aimed to examine how HCWs described their experiences. Methods We conducted a matched case-control study using data from online and phone questionnaires with optional open-ended questions completed by HCWs who sought SARS-CoV-2 testing between March 2020 and March 2021. Conditional logistic regression and thematic analysis were utilized. Results Data from 1340 HCWs were included. Free-text responses were provided by 257 respondents. Adjusting for age, gender, race, occupation, and number of weeks since pandemic was declared, community exposure to a known COVID-19 case (adjusted odds ratio -aOR: 2.45; 95% CI 1.67-3.59), and difficulty accessing personal protective equipment -PPE- (aOR: 1.84; 95% CI 1.07-3.17) were associated with higher infection odds. Care-aides/licensed practical nurses had substantially higher risk (aOR: 2.92; 95% CI 1.49-5.70) than medical staff who had the lowest risk. Direct COVID-19 patient care was not associated with elevated risk. HCWs experiences reflected the phase of the pandemic when they were tested. Suboptimal communication, mental stress, and situations perceived as unsafe were common sources of dissatisfaction. Conclusions Community exposures and occupation were important determinants of infection among HCWs in our study. The availability of PPE and clear communication enhanced a sense of safety. Varying levels of risk between occupational groups call for wider targeting of infection prevention measures. Strategies for mitigating community exposure and supporting HCW resilience are required.

Healthcare worker risk of COVID-19: A 20-month analysis of protective measures from vaccination and beyond (preprint)

BackgroundAs the COVID-19 pandemic continues and new variants such as Omicron emerge, we aimed to re-evaluate vaccine effectiveness as well as impacts of rigorously implemented infection control, public health and occupational health measures in protecting healthcare workers (HCWs). MethodsFollowing a cohort of 21,242 HCWs in Vancouver, British Columbia, Canada, for 20 months since the pandemic started, we used Cox regression and test-negative-design to examine differences in SARS-COV-2 infection rates compared to community counterparts, and within the HCW workforce, assessing the role of occupation, testing accessibility, vaccination rates, and vaccine effectiveness over time. ResultsNurses, allied health professionals and medical staff in this jurisdiction had a significantly lower rate of infection compared to their age-group community counterparts, at 47.4, 41.8, and 55.3% reduction respectively; controlling for vaccine-attributable reductions, the protective impact was still substantial, at 33.4, 28.0, and 36.5% respectively. Licensed practical nurses and care aides had the highest risk of infection among HCWs, more than double that of medical staff. However, even considering differences in vaccination rates, no increase in SARS-CoV-2 infection was found compared to community rates, with combined protective measures beyond vaccination associated with a 17.7% reduced SARS-COV-2 rate in the VCH workforce overall. There was also no evidence of waning immunity within at least 200 days after second dose. ConclusionRigorously implemented occupational health, public health and infection control measures results in a well-protected healthcare workforce with infection rates at or below rates in community counterparts. Greater accessibility of vaccination worldwide is essential; however, as implementing measures to protect this workforce globally also requires considerable health system strengthening in many jurisdictions, we caution against overly focusing on vaccination to the exclusion of other crucial elements for wider protection of HCWs, especially in facing ongoing mutations which may escape current vaccines. Health and care workers are the foundation of health systems and the driving force to achieving universal health coverage and global health security. ...However, too many of them have become infected, ill or died as a result of COVID-19.... These deaths are a tragic loss. They are also an irreplaceable gap in the worlds pandemic response...the world cannot be complacent. World Health Organization Steering Committee for the International Year of Health and Care Workers in 2021 (1)