Severe acute respiratory coronavirus virus 2 (SARS-CoV-2) seroconversion and occupational exposure of employees at a Swiss university hospital: A large longitudinal cohort study

Effectiveness of face masks for reducing transmission of SARS-CoV-2: a rapid systematic review

This rapid systematic review of evidence asks whether (i) wearing a face mask, (ii) one type of mask over another and (iii) mandatory mask policies can reduce the transmission of SARS-CoV-2 infection, either in community-based or healthcare settings. A search of studies published 1 January 2020-27 January 2023 yielded 5185 unique records. Due to a paucity of randomized controlled trials (RCTs), observational studies were included in the analysis. We analysed 35 studies in community settings (three RCTs and 32 observational) and 40 in healthcare settings (one RCT and 39 observational). Ninety-five per cent of studies included were conducted before highly transmissible Omicron variants emerged. Ninety-one per cent of observational studies were at 'critical' risk of bias (ROB) in at least one domain, often failing to separate the effects of masks from concurrent interventions. More studies found that masks (n = 39/47; 83%) and mask mandates (n = 16/18; 89%) reduced infection than found no effect (n = 8/65; 12%) or favoured controls (n = 1/65; 2%). Seven observational studies found that respirators were more protective than surgical masks, while five found no statistically significant difference between the two mask types. Despite the ROB, and allowing for uncertain and variable efficacy, we conclude that wearing masks, wearing higher quality masks (respirators), and mask mandates generally reduced SARS-CoV-2 transmission in these study populations. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'.

Risk of COVID-19 in different groups of healthcare professionals between February 2020 and June 2021 in Finland: a register-based cohort study

BACKGROUND

During the Coronavirus Disease 2019 (COVID-19) pandemic, healthcare workers (HCWs) have been a risk group for COVID-19.

AIM

To assess the cumulative incidence in different groups of HCWs and the risk factors and outcomes of COVID-19 in HCWs between February 2020 and June 2021 in Finland.

METHODS

We linked two national registers, National Infectious Diseases Register (NIDR) and Register of Social Welfare and Healthcare Professionals (Terhikki), using national identity codes. COVID-19 cases were identified from NIDR notifications made by laboratories and physicians, and their healthcare professions from Terhikki. We categorized healthcare professions into seven groups and calculated cumulative incidences using Kaplan-Meier estimate during three periods (1/2/2020-30/6/2020, 1/7/2020-31/12/2020, 1/1/2021-30/6/2021). We identified risk factors in a multivariable model using Cox's regression.

FINDINGS

We identified 8,009 COVID-19-cases among HCWs, with cumulative incidence of 1.79%; 83% were female, median age was 40.9 years (interquartile range, 31.2-51.6). Most COVID-19-cases occurred in nursing assistants (53%) and nurses (17%), with the highest cumulative incidences 2.07% (95%CI, 2.01-2.13%) and 1.82% (95%CI, 1.73-1.91%), respectively. Risk factors were male sex (hazard ratio (HR) 1.2; 95%CI, 1.1-1.3), foreign native language (HR 2.5; 95%CI, 2.2-2.9) and foreign country of birth (HR 1.2; 95%CI, 1.1-1.4). Physician notification data was available for 6,113/8,009 cases (76.3%); 244/6,113 (4.0%) were hospitalized and 37/6,113 (0.6%) in intensive care.

CONCLUSION

Nurses and nursing assistant, especially men and professionals with foreign background, were at higher risk of COVID-19. This should be specifically addressed during training and implementing infection control measures to protect themselves and patients.

Specific COVID-19 risk behaviors and the preventive effect of personal protective equipment among healthcare workers in Japan

As coronavirus disease 2019 (COVID-19) outbreaks in healthcare facilities are a serious public health concern, we performed a case-control study to investigate the risk of COVID-19 infection in healthcare workers. We collected data on participants' sociodemographic characteristics, contact behaviors, installation status of personal protective equipment, and polymerase chain reaction testing results. We also collected whole blood and assessed seropositivity using the electrochemiluminescence immunoassay and microneutralization assay. In total, 161 (8.5%) of 1,899 participants were seropositive between August 3 and November 13, 2020. Physical contact (adjusted odds ratio 2.4, 95% confidence interval 1.1-5.6) and aerosol-generating procedures (1.9, 1.1-3.2) were associated with seropositivity. Using goggles (0.2, 0.1-0.5) and N95 masks (0.3, 0.1-0.8) had a preventive effect. Seroprevalence was higher in the outbreak ward (18.6%) than in the COVID-19 dedicated ward (1.4%). Results showed certain specific risk behaviors of COVID-19; proper infection prevention practices reduced these risks.

Vaccinated Healthcare Workers' Adherence to COVID-19 Prevention Measures and Associated Factors in Northwest Ethiopia: A Facility-Based Cross-Sectional Study

Background

The initial response to coronavirus disease 2019 (COVID-19) was non-pharmaceutical interventions (NPIs). Long-term protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection does not appear to be possible by either infection or vaccination. Thus, traditional herd immunity seems impossible. In addition to increasing vaccination rates, NPIs may be needed.

Methods

A facility-based cross-sectional study was conducted among vaccinated healthcare workers. The study took place from July 15 to August 15, 2022. A self-administered questionnaire was used for data collection. In a multivariable logistic regression model, a p-value of less than 0.05 was considered statistically significant.

Results

Four hundred eleven healthcare workers were included in the study. Sixty percent of participants were fully vaccinated. After vaccination, 10.2% of respondents reported infection with SARS-CoV-2. The study showed that 49.4% of participants had a good knowledge of the efficacy and safety of vaccines against SARS-CoV-2. In this study, 36% of individuals adhered well to the COVID-19 prevention strategies. Good knowledge of the efficacy and safety of SARS-CoV-2 vaccines (AOR = 1.69, 95% CI: 1.03-2.78) increased the odds of implementing preventive measures. Healthcare workers who perceived a low and medium risk of SARS-CoV-2 infection after vaccination and who were knowledgeable about SARS-CoV-2 breakthrough infections were less likely to follow preventive measures.

Conclusion

The knowledge of healthcare workers regarding the efficacy and safety of vaccines against SARS-CoV-2 was comparable. However, a large proportion of healthcare workers poorly adhered to prevention practices. Therefore, to reduce the risk of SARS-CoV-2 infection among healthcare professionals, prevention strategies must be continuously evaluated and awareness of the need for preventive measures must be raised even after vaccination.

Risk of SARS-CoV-2 Acquisition in Health Care Workers According to Cumulative Patient Exposure and Preferred Mask Type

This cohort study compares the risk of infection with SARS-CoV-2 among health care workers by mask preference and level of patient exposure.

Evaluation of Screening Program and Phylogenetic Analysis of SARS-CoV-2 Infections among Hospital Healthcare Workers in Liège, Belgium

Healthcare workers (HCWs) are known to be at higher risk of developing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections although whether these risks are equal across all occupational roles is uncertain. Identifying these risk factors and understand SARS-CoV-2 transmission pathways in healthcare settings are of high importance to achieve optimal protection measures. We aimed to investigate the implementation of a voluntary screening program for SARS-CoV-2 infections among hospital HCWs and to elucidate potential transmission pathways though phylogenetic analysis before the vaccination era. HCWs of the University Hospital of Liège, Belgium, were invited to participate in voluntary reverse transcriptase-polymerase chain reaction (RT-PCR) assays performed every week from April to December 2020. Phylogenetic analysis of SARS-CoV-2 genomes were performed for a subgroup of 45 HCWs. 5095 samples were collected from 703 HCWs. 212 test results were positive, 15 were indeterminate, and 4868 returned negative. 156 HCWs (22.2%) tested positive at least once during the study period. All SARS-CoV-2 test results returned negative for 547 HCWs (77.8%). Nurses (p < 0.05), paramedics (p < 0.05), and laboratory staff handling respiratory samples (p < 0.01) were at higher risk for being infected compared to the control non-patient facing group. Our phylogenetic analysis revealed that most positive samples corresponded to independent introduction events into the hospital. Our findings add to the growing evidence of differential risks of being infected among HCWs and support the need to implement appropriate protection measures based on each individual’s risk profile to guarantee the protection of both HCWs and patients. Furthermore, our phylogenetic investigations highlight that most positive samples correspond to distinct introduction events into the hospital.

P2/N95 respirators & surgical masks to prevent SARS-CoV-2 infection: Effectiveness & adverse effects

BACKGROUND

Millions of people have acquired and died from SARS-CoV-2 infection during the COVID-19 pandemic. Healthcare workers (HCWs) are required to wear personal protective equipment (PPE), including surgical masks and P2/N95 respirators, to prevent infection while treating patients. However, the comparative effectiveness of respirators and masks in preventing SARS-CoV-2 infection and the likelihood of experiencing adverse events (AEs) with wear are unclear.

METHODS

Searches were carried out in PubMed, Europe PMC and the Cochrane COVID-19 Study Register to 14 June 2021. A systematic review of comparative epidemiological studies examining SARS-CoV-2 infection or AE incidence in HCWs wearing P2/N95 (or equivalent) respirators and surgical masks was performed. Article screening, risk of bias assessment and data extraction were duplicated. Meta-analysis of extracted data was carried out in RevMan.

RESULTS

Twenty-one studies were included, with most having high risk of bias. There was no statistically significant difference in respirator or surgical mask effectiveness in preventing SARS-CoV-2 infection (OR 0.85, [95%CI 0.72, 1.01]). Healthcare workers experienced significantly more headaches (OR 2.62, [95%CI 1.18, 5.81]), respiratory distress (OR 4.21, [95%CI 1.46, 12.13]), facial irritation (OR 1.80, [95%CI 1.03, 3.14]) and pressure-related injuries (OR 4.39, [95%CI 2.37, 8.15]) when wearing respirators compared to surgical masks.

CONCLUSION

The existing epidemiological evidence does not enable definitive assessment of the effectiveness of respirators compared to surgical masks in preventing infection. Healthcare workers wearing respirators may be more likely to experience AEs. Effective mitigation strategies are important to ensure the uptake and correct use of respirators by HCWs.

Occupational and community risk of SARS-CoV-2 infection among employees of a long-term care facility: an observational study

BACKGROUND

We investigated the contribution of both occupational and community exposure for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among employees of a university-affiliated long-term care facility (LTCF), during the 1^st pandemic wave in Switzerland (March-June 2020).

METHODS

We performed a nested analysis of a seroprevalence study among all volunteering LTCF staff to determine community and nosocomial risk factors for SARS-CoV-2 seropositivity using modified Poison regression. We also combined epidemiological and genetic sequencing data from a coronavirus disease 2019 (COVID-19) outbreak investigation in a LTCF ward to infer transmission dynamics and acquisition routes of SARS-CoV-2, and evaluated strain relatedness using a maximum likelihood phylogenetic tree.

RESULTS

Among 285 LTCF employees, 176 participated in the seroprevalence study, of whom 30 (17%) were seropositive for SARS-CoV-2. Most (141/176, 80%) were healthcare workers (HCWs). Risk factors for seropositivity included exposure to a COVID-19 inpatient (adjusted prevalence ratio [aPR] 2.6; 95% CI 0.9-8.1) and community contact with a COVID-19 case (aPR 1.7; 95% CI 0.8-3.5). Among 18 employees included in the outbreak investigation, the outbreak reconstruction suggests 4 likely importation events by HCWs with secondary transmissions to other HCWs and patients.

CONCLUSIONS

These two complementary epidemiologic and molecular approaches suggest a substantial contribution of both occupational and community exposures to COVID-19 risk among HCWs in LTCFs. These data may help to better assess the importance of occupational health hazards and related legal implications during the COVID-19 pandemic.

Impact of respirator versus surgical masks on SARS-CoV-2 acquisition in healthcare workers: a prospective multicentre cohort

Background

There is insufficient evidence regarding the role of respirators in the prevention of SARS-CoV-2 infection. We analysed the impact of filtering facepiece class 2 (FFP2) versus surgical masks on the risk of SARS-CoV-2 acquisition among Swiss healthcare workers (HCW).

Methods

Our prospective multicentre cohort enrolled HCW from June to August 2020. Participants were asked about COVID-19 risk exposures/behaviours, including preferentially worn mask type when caring for COVID-19 patients outside of aerosol-generating procedures. The impact of FFP2 on (1) self-reported SARS-CoV-2-positive nasopharyngeal PCR/rapid antigen tests captured during weekly surveys, and (2) SARS-CoV-2 seroconversion between baseline and January/February 2021 was assessed.

Results

We enrolled 3259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users; seroconversion was documented in 85/656 (13%) FFP2 and 426/2255 (19%) surgical mask users. Adjusted for baseline characteristics, COVID-19 exposure, and risk behaviour, FFP2 use was non-significantly associated with decreased risk for SARS-CoV-2-positive swab (adjusted hazard ratio [aHR] 0.8, 95% CI 0.6–1.0) and seroconversion (adjusted odds ratio [aOR] 0.7, 95% CI 0.5–1.0); household exposure was the strongest risk factor (aHR 10.1, 95% CI 7.5–13.5; aOR 5.0, 95% CI 3.9–6.5). In subgroup analysis, FFP2 use was clearly protective among those with frequent (> 20 patients) COVID-19 exposure (aHR 0.7 for positive swab, 95% CI 0.5–0.8; aOR 0.6 for seroconversion, 95% CI 0.4–1.0).

Conclusions

Respirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01070-6.

Reconstruction of transmission chains of SARS-CoV-2 amidst multiple outbreaks in a geriatric acute-care hospital: a combined retrospective epidemiological and genomic study

Background

There is ongoing uncertainty regarding transmission chains and the respective roles of healthcare workers (HCWs) and elderly patients in nosocomial outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in geriatric settings.

Methods

We performed a retrospective cohort study including patients with nosocomial coronavirus disease 2019 (COVID-19) in four outbreak-affected wards, and all SARS-CoV-2 RT-PCR positive HCWs from a Swiss university-affiliated geriatric acute-care hospital that admitted both Covid-19 and non-Covid-19 patients during the first pandemic wave in Spring 2020. We combined epidemiological and genetic sequencing data using a Bayesian modelling framework, and reconstructed transmission dynamics of SARS-CoV-2 involving patients and HCWs, to determine who infected whom. We evaluated general transmission patterns according to case type (HCWs working in dedicated Covid-19 cohorting wards: HCW_covid; HCWs working in non-Covid-19 wards where outbreaks occurred: HCW_outbreak; patients with nosocomial Covid-19: patient_noso) by deriving the proportion of infections attributed to each case type across all posterior trees and comparing them to random expectations.

Results

During the study period (1 March to 7 May 2020), we included 180 SARS-CoV-2 positive cases: 127 HCWs (91 HCW_covid, 36 HCW_outbreak) and 53 patients. The attack rates ranged from 10% to 19% for patients, and 21% for HCWs. We estimated that 16 importation events occurred with high confidence (4 patients, 12 HCWs) that jointly led to up to 41 secondary cases; in six additional cases (5 HCWs, 1 patient), importation was possible with a posterior probability between 10% and 50%. Most patient-to-patient transmission events involved patients having shared a ward (95.2%, 95% credible interval [CrI] 84.2%-100%), in contrast to those having shared a room (19.7%, 95% CrI 6.7%-33.3%). Transmission events tended to cluster by case type: patient_noso were almost twice as likely to be infected by other patient_noso than expected (observed:expected ratio 2.16, 95% CrI 1.17-4.20, p=0.006); similarly, HCW_outbreak were more than twice as likely to be infected by other HCW_outbreak than expected (2.72, 95% CrI 0.87-9.00, p=0.06). The proportion of infectors being HCW_covid was as expected as random. We found a trend towards a greater proportion of high transmitters (≥2 secondary cases) among HCW_outbreak than patient_noso in the late phases (28.6% vs. 11.8%) of the outbreak, although this was not statistically significant.

Conclusions

Most importation events were linked to HCW. Unexpectedly, transmission between HCW_covid was more limited than transmission between patients and HCW_outbreak. This finding highlights gaps in infection control and suggests the possible areas of improvements to limit the extent of nosocomial transmission.

Funding

This study was supported by a grant from the Swiss National Science Foundation under the NRP78 funding scheme (Grant no. 4078P0_198363).

SARS-CoV-2-specific B- and T-cell immunity in a population-based study of young Swedish adults

Background

Young adults are now considered major spreaders of coronavirus disease 2019 (COVID-19) disease. Although most young individuals experience mild to moderate disease, there are concerns of long-term adverse health effects. The impact of COVID-19 disease and to which extent population-level immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exists in young adults remain unclear.

Objective

We conducted a population-based study on humoral and cellular immunity to SARS-CoV-2 and explored COVID-19 disease characteristics in young adults.

Methods

We invited participants from the Swedish BAMSE (Barn [Children], Allergy Milieu, Stockholm, Epidemiology) birth cohort (age 24-27 years) to take part in a COVID-19 follow-up. From 980 participants (October 2020 to June 2021), we here present data on SARS-CoV-2 receptor-binding domain–specific IgM, IgA, and IgG titers measured by ELISA and on symptoms and epidemiologic factors associated with seropositivity. Further, SARS-CoV-2–specific memory B- and T-cell responses were detected for a subpopulation (n = 108) by ELISpot and FluoroSpot.

Results

A total of 28.4% of subjects were seropositive, of whom 18.4% were IgM single positive. One in 7 seropositive subjects was asymptomatic. Seropositivity was associated with use of public transport, but not with sex, asthma, rhinitis, IgE sensitization, smoking, or body mass index. In a subset of representative samples, 20.7% and 35.0% had detectable SARS-CoV-2 specific B- and T-cell responses, respectively. B- and T-cell memory responses were clearly associated with seropositivity, but T-cell responses were also detected in 17.2% of seronegative subjects.

Conclusions

Assessment of IgM and T-cell responses may improve population-based estimations of SARS-CoV-2 infection. The pronounced surge of both symptomatic and asymptomatic infections among young adults indicates that the large-scale vaccination campaign should be continued.