Risk of SARS-CoV-2 exposure among hospital healthcare workers in relation to patient contact and type of care

Impact of age on the transmission of SARS-CoV-2 in healthcare workers : Influence of nonoccupational risk factors

BACKGROUND

The incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV‑2) infection was highest among older adults early in the COVID-19 pandemic; however, this pattern was later reversed with young adults showing the highest incidence. The aim of this study was to identify risk factors in healthcare workers (HCWs) associated with this evolution.

METHODS

We conducted a survey nested within a prospective cohort study of 680 HCWs from a tertiary referral public hospital who received 2 doses of SARS-CoV‑2 vaccine in January and February 2021 (VACCICO-VAO cohort). In October 2022 all participants were invited to participate in a survey. Risk factors were tested for association with COVID-19 ever, the number of COVID-19 episodes, and the time to the first episode.

RESULTS

Among 350 respondents (51% response rate, 90% female, mean age 48.1 years), 323 COVID-19 episodes were diagnosed during the study period. Multivariable analysis revealed that age < 35 years vs. > 50 years (odds ratio, OR 2.12, 95% confidence interval, CI 1.27-3.51; P = 0.004) and not maintaining social distance at social events (OR: 1.82, 95% CI: 1.16-3.19; P = 0.011) were associated with a higher risk of COVID-19. Age < 35 years (hazard ratio, HR 1.70, 95% CI 1.14-2.54; P = 0.010), and not maintaining social distance (HR 1.34, 95% CI 1.05-1.72; P = 0.020) were also associated with the time to the first episode.

CONCLUSIONS

The youngest HCWs had the highest incidence rate of COVID-19, which was not explained by occupational risk factors or health conditions. The increase in nonoccupational exposure since the end of the lockdowns in summer 2020 could by a key factor.

High seroprevalence of SARS-CoV-2 antibodies in healthcare workers in COVID-19 wards indicates an occupational hazard-a prospective cohort study during the first year of the COVID-19 pandemic in Kalmar County, Sweden

The aim of this study is to report the seroprevalence of SARS-CoV-2 antibodies in healthcare workers with various risk of occupational exposure in Kalmar County, Sweden, during the first year of the coronavirus disease 2019 (COVID-19) pandemic. We performed SARS-CoV-2 antibody measurements at four time points, from May 2020 to May 2021, in 401 healthcare workers (HCW) at seven hospital wards and two residential care facilities, with different risk of SARS-CoV-2 exposure. Overall, the prevalence of SARS-CoV-2 antibodies in HCW in Kalmar County was high compared to similar studies from other countries and increased from May 2020 to May 2021. Initially, 14% of the participants were SARS-CoV-2 seropositive. This number increased to 18% in September and 21% in December 2020. In May 2021, the prevalence of antibodies to nucleocapsid antigen had increased to 28%, while antibodies to spike protein had increased to 95% due to vaccination. A large variation in seroprevalence between different wards was detected and HCW in a COVID-19 designated ward had significantly higher seroprevalence than HCW working in wards without COVID-19 patients, with a risk ratio of 7.28, (95% CI 2.38-22.33) in May 2020. Our findings suggest a relationship between occupational COVID-19 exposure and seropositivity which implies that efficient hygiene routines for health- and social care workers are essential to avoid that COVID-19 care will constitute an occupational hazard.

The COVID-19 Pandemic and Health and Care Workers: Findings From a Systematic Review and Meta-Analysis (2020-2021)

Objectives: The COVID-19 pandemic has greatly impacted health and care workers (HCW) globally, whom are considered at greater risk of infection and death. This study aims to document emerging evidence on disease prevalence, clinical outcomes, and vaccination rates of HCWs. Methods: Three databases were surveyed resulting on 108 final articles between July-December 2020 (period 1) and January-June 2021 (period 2). Results: Amongst the overall 980,000 HCWs identified, in period 1, the estimates were 6.1% (95% CI, 4.1-8.8) for the PCR positivity rate. Regarding outcomes, the hospitalization prevalence was 1.6% (95% CI, 0.7-3.9), and mortality rate of 0.3% (95% CI, 0.1-0.8). In period 2, the PCR positivity rate was 8.1% (95% CI, 4.6-13.8). Analysis of outcomes revealed a hospitalization rate of 0.7% (95% CI 0.3-1.8), and average mortality rate of 0.3% (95% CI 0.1-0.9). Our analysis indicated a HCW vaccination rate of 59.0% (95% CI, 39.4-76.1). Conclusion: Studies from the latter half of 2020 to the first half of 2021 showed a slight increasing trend in PCR positivity among HCW, along with improved clinical outcomes in the 1-year period of exposure. These results correlate well with the improving uptake of COVID-19 vaccination globally.

Occupational Risk Factors for SARS-CoV-2 Infection in Hospital Health Care Workers: A Prospective Nested Case-Control Study

Introduction: Health Care Workers (HCWs) are at a particular high risk of SARS-CoV-2 infection due to direct and indirect exposure to COVID-19 patients and Aerosol-Generating Procedures (AGPs). The aim of the study was to assess the risk factors for SARS-CoV-2 infection in HCWs exposed to COVID-19 patients, to evaluate the adherence and effectiveness of Infection Prevention and Control (IPC) measures, to describe the clinical presentation for SARS-CoV-2 infection in HCWs and to determine serological responses in HCWs. Methods: HCWs exposed to COVID-19 patients during the previous 14 days with a confirmed case status were recruited as cases; HCWs exposed to COVID-19 patients during the previous 14 days in the same ward without a suspected/probable/confirmed case status were recruited as controls. Serum samples were collected as soon as possible and after 21–28 days from all participants. Data were collected with a WHO standardized questionnaire as soon as possible and after 21–28 days. Results: All social, occupational and personal variables considered were not associated with an increased risk of SARS-CoV-2 infection. Conclusions: Our study showed a high knowledge of IPC measures and very high PPE use among HCWs.

Seroprevalence of SARS-CoV-2 and Risk Assessment Among Healthcare Workers at a Dedicated Tertiary Care COVID-19 Hospital in Delhi, India: A Cohort Study

Background

Healthcare workers (HCWs) have a substantially higher risk of Covid-19 infection but there is a paucity of information on the risk factors of disease transmission in high-burden real-world settings.

The study objective was to determine the seroprevalence of SARS-CoV-2 among healthcare workers in a high-burden Covid-19 setting and to estimate the incidence and identify the risk factors of infection.

Methods

This was a prospective observational cohort study amongst doctors and nurses working at a dedicated Covid-19 tertiary care government hospital in Delhi, India. A baseline blood sample (2-3ml) was collected from all the participants to test for the presence of total SARS-CoV-2 antibodies. The HCWs that were seronegative (non-reactive) at baseline were followed-up for ≥21≤28 days with the collection of a second blood sample to assess for the incidence of SARS-CoV-2 infection.

Results

A total of 321 (51.3%, 95% C.I 47.4, 55.3) HCWs were detected with SARS-CoV-2 antibodies on baseline examination. The seroprevalence, when adjusted for assay characteristics, was 54.5% (95% C.I 50.3, 58.6). On bivariate analysis, SARS-CoV-2 antibody positivity lacked statistically significant association with either age, sex, occupation, cumulative duty duration, and smoking status. The incidence of seroconversion in the baseline seronegative cohort on follow-up after 21-28 days was observed in 35 (14.9%) HCWs (n=245). Furthermore, the self-reported adherence to infection prevention and control measures did not show a statistically significant association with antibody positivity in the HCWs, neither at baseline nor on follow-up.

Conclusions 

The high risk of SARS-CoV-2 transmission in HCWs may be substantially reduced by adherence to Infection Prevention Control (IPC) and protective measures. 

Potential SARS-CoV-2 infectiousness among asymptomatic healthcare workers

A majority of SARS-CoV-2 infections are transmitted from a minority of infected subjects, some of which may be symptomatic or pre-symptomatic. We aimed to quantify potential infectiousness among asymptomatic healthcare workers (HCWs) in relation to prior or later symptomatic disease. We previously (at the onset of the SARS-CoV-2 epidemic) performed a cohort study of SARS-CoV-2 infections among 27,000 healthcare workers (HCWs) at work in the capital region of Sweden. We performed both SARS-CoV-2 RT-PCR and serology. Furthermore, the cohort was comprehensively followed for sick leave, both before and after sampling. In the present report, we used the cohort database to quantify potential infectiousness among HCWs at work. Those who had sick leave either before or after sampling were classified as post-symptomatic or pre-symptomatic, whereas the virus-positive subjects with no sick leave were considered asymptomatic. About 0.2% (19/9449) of HCW at work were potentially infectious and pre-symptomatic (later had disease) and 0.17% (16/9449) were potentially infectious and asymptomatic (never had sick leave either before nor after sampling). Thus, 33% and 28% of all the 57 potentially infectious subjects were pre-symptomatic or asymptomatic, respectively. When a questionnaire was administered to HCWs with past infection, only 10,5% of HCWs had had no indication at all of having had SARS-CoV-2 infection ("truly asymptomatic"). Our findings provide a unique quantification of the different groups of asymptomatic, potentially infectious HCWs.

Risk for SARS-CoV-2 infection in healthcare workers outside hospitals: A real-life immuno-virological study during the first wave of the COVID-19 epidemic

OBJECTIVES

Most COVID-19 related infections and deaths may occur in healthcare outside hospitals. Here we explored SARS-CoV-2 infections among healthcare workers (HCWs) in this setting.

DESIGN

All healthcare providers in Stockholm, Sweden were asked to recruit HCWs at work for a study of past or present SARS-CoV-2 infections among HCWs. Study participants This study reports the results from 839 HCWs, mostly employees of primary care centers, sampled in June 2020.

RESULTS

SARS-CoV-2 seropositivity was found among 12% (100/839) of HCWs, ranging from 0% to 29% between care units. Seropositivity decreased by age and was highest among HCWs <40 years of age. Within this age group there was 19% (23/120) seropositivity among women and 11% (15/138) among men (p<0.02). Current infection, as measured using PCR, was found in only 1% and the typical testing pattern of pre-symptomatic potential "superspreaders" found in only 2/839 subjects.

CONCLUSIONS

Previous SARS-CoV-2 infections were common among younger HCWs in this setting. Pre-symptomatic infection was uncommon, in line with the strong variability in SARS-CoV-2 exposure between units. Prioritizing infection prevention and control including sufficient and adequate personal protective equipment, and vaccination for all HCWs are important to prevent nosocomial infections and infections as occupational injuries during an ongoing pandemic.

Differences in risk for SARS-CoV-2 infection among healthcare workers

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Clustering of SARS-CoV-2 exposure among HCWs in specific hospital wards was found.

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SARS-CoV-2 infection was most common among nurse assistants in COVID-19 wards.

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HCWs in wards with infectious diseases experience did not have increased risk.

Healthcare workers (HCWs) are a risk group for SARS-CoV-2 infection, but which healthcare work that conveys risk and to what extent such risk can be prevented is not clear. Starting on April 24th, 2020, all employees at work (n = 15,300) at the Karolinska University Hospital, Stockholm, Sweden were invited and 92% consented to participate in a SARS-CoV-2 cohort study. Complete SARS-CoV-2 serology was available for n = 12,928 employees and seroprevalences were analyzed by age, sex, profession, patient contact, and hospital department. Relative risks were estimated to examine the association between type of hospital department as a proxy for different working environment exposure and risk for seropositivity, adjusting for age, sex, sampling week, and profession. Wards that were primarily responsible for COVID-19 patients were at increased risk (adjusted OR 1.95 (95% CI 1.65–2.32) with the notable exception of the infectious diseases and intensive care units (adjusted OR 0.86 (95% CI 0.66–1.13)), that were not at increased risk despite being highly exposed. Several units with similar types of work varied greatly in seroprevalences. Among the professions examined, nurse assistants had the highest risk (adjusted OR 1.62 (95% CI 1.38–1.90)). Although healthcare workers, in particular nurse assistants, who attend to COVID-19 patients are a risk group for SARS-CoV-2 infection, several units caring for COVID-19 patients had no excess risk. Large variations in seroprevalences among similar units suggest that healthcare work-related risk of SARS-CoV-2 infection may be preventable.