Seroprevalence of SARS-CoV-2 IgG specific antibodies among healthcare workers in the Northern Metropolitan Area of Barcelona, Spain, after the first pandemic wave

Mapping the viral battlefield: SARS-CoV-2 infection dynamics among healthcare workers in Brazil

BACKGROUND

Understanding the dynamics of SARS-CoV-2 viral infection and factors associated with in-hospital transmission rates among healthcare workers (HCW) is crucial for their protection. Brazil experienced high mortality rates due to COVID-19, and limited data are available on transmission of SARS-CoV-2 infection among HCW. This cohort study aimed to assess the dynamic of SARS-CoV-2 infections in HCW from two tertiary hospitals in central Brazil, one of them a Reference Hospital for COVID-19.

METHODS

From May 2020 to January 2021, 554 HCW directly involved with COVID-19 care were followed through 12 biweekly visits. During these visits, blood, nasal, and oropharyngeal samples were collected, and participants underwent interviews. SARS-CoV-2 detection was carried out using RT-qPCR, while the assessment of seroprevalence was based on IgG detection. Additionally, 35 positive samples underwent viral whole-genome sequencing.

RESULTS

The infection prevalence, as per RT-qPCR, was 28.5% (24.9-32.4), reflecting an overall attack rate ranging from 0.5% to 9.5%, marked by two peaks in August and December 2020. Oligosymptomatic and asymptomatic infections accounted for 14% of prevalent infections. The seroprevalence rate stood at 25.8%. The hospitalization rate was 8.2%, with a fatality rate of 1.3%. Risk factors associated with a positive diagnosis of COVID-19 included being male, working at the referral hospital, having a graduate-education level, and using hydroxychloroquine and zinc for prevention or treatment. One reinfection was identified. Absenteeism was 56.6%. The infection dynamics mirrored the pattern observed in the general population.

CONCLUSION

One-third of the professionals in the followed cohort were infected. Being male, working in a COVID-19 referral center, having a low level of education, and using medications for preventive treatment represented risk factors. Healthcare workers at the COVID-19 referral hospital exhibited a higher incidence rate compared to those at the non-referral hospital, increasing the plausibility that some of the infections occur in the hospital environment.

Risk of SARS-CoV-2 infection before and after the Omicron wave in a cohort of healthcare workers in Ontario, Canada

BACKGROUND

Longitudinal healthcare worker (HCW) cohorts throughout the COVID-19 pandemic provide a unique opportunity to study the relative contributions of various exposures to infection risk over time. This study aimed to examine how demographic, health, occupational, household and community factors influenced the SARS-CoV-2 infection risk in a cohort of HCWs in Southeastern Ontario, Canada, during the early pandemic and the Omicron waves. We compared the contribution of these factors to infection risk and explored the implications for future epidemic preparedness and the protection of HCWs.

METHODS

We conducted a longitudinal analysis using data from a cohort of HCWs recruited from one acute care hospital and four long-term care homes. The analysis was divided into two periods: the initial phase of the pandemic (period #1) and the first three Omicron waves (period #2). We employed Poisson regression for period #1 and Cox regression for period #2 to examine associations of demographic factors (age, sex, ethnicity, migration status, income insufficiency), health factors (chronic conditions, smoking history, SARS-CoV-2 vaccination status), household factors (exposure to COVID-19), occupational factors (work role, exposure to COVID-19 patients, personal protective equipment access, aerosol-generating procedures) and community exposures (use of masks, distance, hand-washing) with SARS-CoV-2 infection.

RESULTS

At period #1, 17/208 (8.2%) HCWs reported having had SARS-CoV-2 infection. At period #2, 65/167 (38.3%) reported at least one SARS-CoV-2 infection. In period #1, factors associated with increased risk of infection included working in a long-term care home, exposure to more COVID-19-positive patients, working as a nurse or therapist, and inadequate use of personal protective equipment. In period #2, the hazard of infection was higher among HCWs who had COVID-19-infected children at home, whereas the use of protective measures in the community (maintaining social distance, mask-wearing) and receiving a vaccine booster were associated with reduced risk. Providing care to COVID-19 patients was not associated with the risk of acquiring SARS-CoV-2 infection at period #2.

CONCLUSIONS

During the Omicron wave, community and household exposures, but not occupational exposure to COVID-19 cases, were the primary factors contributing to infection risk in HCWs. This contrasts with the early waves of the pandemic where occupational exposures played a significant role. These findings may be explained by the effectiveness of institutional interventions in reducing the risk of SARS-CoV-2 transmission in healthcare settings, alongside the failure of community-level interventions to mitigate risk during the Omicron period.

Prevalence and risk factors of SARS-CoV-2 antibody responses among healthcare workers (June 2020-November 2021)

BACKGROUND

To assess SARS-CoV-2 seroprevalence in healthcare workers (HCW) with sampling in June and October 2020 and April and November 2021.

METHODS

Observational and prospective study in 2455 HCW with serum sampling. Antibodies against SARS-CoV-2 nucleocapsid and occupational, social and health risk factors were assessed at each time point.

RESULTS

Seropositivity for SARS-CoV-2 in HCW increased from 11.8% in June 2020 to 28.4% in November 2021. Of those with a positive test in June 2020, 92.1% remained with a positive test, 6.7% had an indeterminate test and 1.1% had a negative test in November 2021. Non-diagnosed carriers represented 28.6% in June 2020 and 14.6% in November 2021. Nurses and nursing assistants showed the highest prevalence of seropositivity. Close contact (at home or in the hospital) with Covid-19 cases without protection and working in the frontline were the main risk factors. A total of 88.8% HCW were vaccinated, all with a positive serological response in April 2021, but levels of antibodies decreased about 65%, and two vaccinated persons presented a negative serological test against spike protein in November 2021. Levels of spike antibodies were higher in those vaccinated with Moderna compared with Pfizer and the percentage of antibody reduction was higher with Pfizer vaccine.

CONCLUSIONS

This study shows that seroprevalence of SARS-CoV-2 antibodies among HCW doubled that of the general population and that protection both at the workplace and in the socio-familial field was associated with a lower risk of infection, which stabilized after vaccination.

COVID-19 infection and seroconversion rates in healthcare workers in Lebanon: An observational study

Coronavirus disease 2019 (COVID-19) infection is a recent pandemic. Healthcare workers (HCW) are at high risk of acquiring the infection and transmitting it to others. Seroprevalence for COVID-19 among HCW varies between countries, hospitals in the same country and even among different departments in the same hospital. In this study, we aim to determine the prevalence of severe acute respiratory syndrome coronavirus 2 antibodies and the seroconversion among the HCW in our hospital. A total of 203 HCW were included. The rate of conversion to seropositive was 19.7% in total, with a rate of 13.4% in female versus 25% in male. The seropositivity in the House keeping group was 83%, followed by 45% in the COVID Floor while the seropositivity in the Anesthesia was 4% and the Infection Control 0%. The highest seropositivity rate in the COVID floor, and in the intensive care unit was explained by the long time spent with the patients. While in the inhalation team and the anesthesia, the lower rates of seropositivity was due to the N95 mask wearing the whole time. Seropositivity for COVID-19 in HCW is a major public health concern. Policies should be implemented to better protect HCWs.

Seroprevalence of SARS-CoV-2 in a Fully Operative Dentistry Academic Center in Madrid (Spain) During the De-escalation Phase of the COVID-19 Pandemic. Are Our Dentists at Greater Risk?

PURPOSE

To determine the prevalence of COVID-19 infection among dental professionals at an Academic Center in Madrid (Spain) at the beginning of the pandemic's de-escalation phase.

MATERIALS AND METHODS

A cross-sectional study was designed. COVID-19 infection was determined by membrane-based immunoassay qualitative detection of IgG and IgM antibodies in human whole blood. Age, sex, race and professional qualification were recorded, as were symptoms compatible with COVID-19 infection whenever present. Data collected were analysed by means of descriptive and qualitative (X2) statistical analyses.

RESULTS

A total of 195 individuals were included (40 administrative professionals and 155 dentists). Seroprevalence at the end of the de-escalation phase was 20.0% among all the participants. The highest prevalence was found among the orthodontists (34.8%), followed by the paediatric dentists (28.6%) and oral surgeons (14.7%). Most subjects were positive for IgG and negative for IgM (79.5%).

CONCLUSIONS

The seroprevalence of SARS-CoV-2 among dental professionals at the end of the de-escalation phase after the first wave of the pandemic was almost double the seroprevalence of the general population. Orthodontists had the highest rates of SARS-CoV-2 infection.

Seroprevalence in health care workers during the later phase of the second wave: Results of three hospitals in Serbia, prior to vaccine administration

BACKGROUND

Since the COVID-19 pandemic has started, Serbia has faced problems in implementing proper public health measures in the population, including non-pharmaceutical interventions, as well as protecting health care workers (HCWs) from disease, like all other countries. This study aimed to estimate COVID-19 seroprevalence and evaluate the risk perception of COVID-19 among HCWs in three different hospitals in Belgrade, Serbia: non-COVID hospital, Emergency Center (EC), and dedicated COVID hospital.

METHODS

A cross-sectional study was conducted in three hospitals during the second wave of the outbreak in Serbia, from June to early October. All staff in these hospitals were invited to voluntarily participate in blood sampling for IgG antibodies against SARS-CoV-2 and questionnaire testing. The questionnaire included socio-demographic characteristics, known exposure to COVID-19 positive persons, previous signs and symptoms related to COVID-19 infection since the outbreak had started in our country, and SARS-CoV-2 PCR testing.

RESULTS

The overall prevalence of SARS-CoV-2 antibody among 1580 HCWs was 18.3 % [95 % CI 16.4-20.3 %]. Significantly higher prevalence of HCWs with positive results for the serum IgG antibody test was observed in COVID hospital (28.6 %, 95 %CI: 24.0-33.6 %) vs. prevalence in the EC (12.6 %, 95 %CI: 10.1-15.4 %), and in the non-COVID hospital (18.3 %, 95 %CI: 15.2-26.7 %). The prevalence adjusted for declared test sensitivity and specificity would be 16.8 %; that is 27.4 % in COVID-19 hospital, 10.9 % in EC, and 16.8 % in non-COVID hospital. In multivariate logistic regression analysis, the independent predictors for seropositivity were working in COVID-hospital, the profession of physician, and the presence of the following symptoms: fever, shortness of breath, and anosmia/ageusia.

CONCLUSIONS

We found an overall seropositivity rate of 18.3 % and 16.0 % of the adjusted rate that is higher than seroprevalence obtained in similar studies conducted before vaccinations started. The possibility that patients in non-COVID dedicated hospitals might also be infectious, although PCR tested, imposes the need for the use of personal protective equipment also in non-COVID medical institutions.

Follow up of the Humoral Response in Healthcare Workers after the Administration of Two Dose of the Anti SARS-CoV-2 Vaccines-Effectiveness in Delta Variant Breakthrough Infections

The implementation of vaccination among healthcare workers (HCWs) allowed the management of the pandemic in a manner that differed from that in the first waves. It has been demonstrated that the mRNA vaccines elicit good humoral responses but that there are still breakthrough infections. In summer 2021, a fifth wave emerged, despite the good coverage of HCWs in Spain. We aimed to study the SARS-CoV-2 IgG antibody levels as a marker to predict the possibility of Delta variant infections after vaccination after a seroepidemiological campaign. Of the 5000 participants, a total of 4902 (98.04%) showed a positive result in the serological anti-S test and only 98 (1.96%) were negative. Among the 4368 fully vaccinated participants, only in five cases was the serology negative. Of the total number of participants that received antibody results during the study, 162 were PCR positive in the subsequent two months. Among these, 151 were fully vaccinated (two doses). Significant differences between antibody BAU/mL levels were found between PCR positive and non-PCR positive participants (p < 0.01). The median of BAU/mL was higher in those vaccinated patients with no infection (1260 BAU/mL; 465−2080) versus infected patients (661 BAU/mL; 361−2080). These data support the idea that vaccines play an important role in the control of the pandemic, especially among HCWs at the time of the Delta variant circulation. More studies with other variants of concern must be performed in order to establish a correlation between the levels of IgG and the new infections.

Hospital-wide SARS-CoV-2 antibody screening of 4840 staff members in a University Medical Center in France: a cross-sectional study

OBJECTIVES

Healthcare workers are more likely to be infected by SARS-CoV-2. In order to assess the infectious risk associated with working in a hospital, we sought to estimate the proportion of healthcare professionals infected with SARS-CoV-2 by screening staff in a University Medical Center in France.

SETTING

A hospital-wide screening campaign (comprising a serological test and a questionnaire) ran from 18 May to 26 July 2020.

PRIMARY AND SECONDARY OUTCOME MEASURES

The seroprevalence rate was analysed in a multivariate analysis according to sociodemographic variables (age, sex and profession), exposure to SARS-CoV-2 and symptoms.

RESULTS

A total of 4840 professionals were included, corresponding to 74.5% of the centre's staff. The seroprevalence rate (95% CI) was 9.7% (7.0% to 12.4%). Contact with a confirmed case of COVID-19 was significantly associated with seropositivity (OR (95% CI: 1.43, (1.15 to 1.78)). The seroprevalence rate was significantly higher among nursing assistants (17.6%) than among other healthcare professionals. The following symptoms were predictive of COVID-19: anosmia (OR (95% CI): 1.55, (1.49 to 1.62)), ageusia (1.21, (1.16 to 1.27)), fever (1.15, (1.12 to 1.18)), myalgia (1.03, (1.01 to 1.06)) and headache (1.03, (1.01 to 1.04)).

COVID-19 among workers of a comprehensive cancer centre between first and second epidemic waves (2020): a seroprevalence study in Catalonia, Spain

OBJECTIVES

Patients with cancer are at higher risk for severe COVID-19 infection. COVID-19 surveillance of workers in oncological centres is crucial to assess infection burden and prevent transmission. We estimate the SARS-CoV-2 seroprevalence among healthcare workers (HCWs) of a comprehensive cancer centre in Catalonia, Spain, and analyse its association with sociodemographic characteristics, exposure factors and behaviours.

DESIGN

Cross-sectional study (21 May 2020-26 June 2020).

SETTING

A comprehensive cancer centre (Institut Català d'Oncologia) in Catalonia, Spain.

PARTICIPANTS

All HCWs (N=1969) were invited to complete an online self-administered epidemiological survey and provide a blood sample for SARS-CoV-2 antibodies detection.

PRIMARY OUTCOME MEASURE

Prevalence (%) and 95% CIs of seropositivity together with adjusted prevalence ratios (aPR) and 95% CI were estimated.

RESULTS

A total of 1266 HCWs filled the survey (participation rate: 64.0%) and 1238 underwent serological testing (97.8%). The median age was 43.7 years (p25-p75: 34.8-51.0 years), 76.0% were female, 52.0% were nursing or medical staff and 79.0% worked on-site during the pandemic period. SARS-CoV-2 seroprevalence was 8.9% (95% CI 7.44% to 10.63%), with no differences by age and sex. No significant differences in terms of seroprevalence were observed between onsite workers and teleworkers. Seropositivity was associated with living with a person with COVID-19 (aPR 3.86, 95% CI 2.49 to 5.98). Among on-site workers, seropositive participants were twofold more likely to be nursing or medical staff. Nursing and medical staff working in a COVID-19 area showed a higher seroprevalence than other staff (aPR 2.45, 95% CI 1.08 to 5.52).

CONCLUSIONS

At the end of the first wave of the pandemic in Spain, SARS-CoV-2 seroprevalence among Institut Català d'Oncologia HCW was lower than the reported in other Spanish hospitals. The main risk factors were sharing household with infected people and contact with COVID-19 patients and colleagues. Strengthening preventive measures and health education among HCW is fundamental.

Organ dysfunction and death in patients admitted to hospital with COVID-19 in pandemic waves 1 to 3 in British Columbia, Ontario and Quebec, Canada: a cohort study

BACKGROUND

There have been multiple waves in the COVID-19 pandemic in many countries. We sought to compare mortality and respiratory, cardiovascular and renal dysfunction between waves in 3 Canadian provinces.

METHODS

We conducted a substudy of the ARBs CORONA I study, a multicentre Canadian pragmatic observational cohort study that examined the association of pre-existing use of angiotensin receptor blockers with outcomes in adults admitted to hospital with acute COVID-19 up to April 2021 from 9 community and teaching hospitals in 3 Canadian provinces (British Columbia, Ontario and Quebec). We excluded emergency department admissions without hospital admission, readmissions and admissions for another reason. We used logistic and 0-1-inflated β regression models to compare 28-day and in-hospital mortality, and the use of invasive mechanical ventilation, vasopressors and renal replacement therapy (RRT) between the first 3 waves of the COVID-19 pandemic in these provinces.

RESULTS

A total of 520, 572 and 245 patients in waves 1, 2 and 3, respectively, were included. Patients in wave 3 were on average younger and had fewer comorbidities than those in waves 1 and 2. The unadjusted 28-day mortality rate was significantly lower in wave 3 (7.8%) than in wave 1 (18.3%) (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.24-0.78) and wave 2 (16.3%) (OR 0.46, 95% CI 0.27-0.79). After adjustment for differences in baseline characteristics, the difference in 28-day mortality remained significant (adjusted OR wave 3 v. wave 1: 0.46, 95% CI 0.26-0.81; wave 3 v. wave 2: 0.52, 95% CI 0.29-0.91). In-hospital mortality findings were similar. Use of invasive mechanical ventilation or vasopressors was less common in waves 2 and 3 than in wave 1, and use of RRT was less common in wave 3 than in wave 1.

INTERPRETATION

Severity of illness decreased (lower mortality and less use of organ support) across waves among patients admitted to hospital with acute COVID-19, possibly owing to changes in patient demographic characteristics and management, such as increased use of dexamethasone. Continued application of proven therapies may further improve outcomes.

STUDY REGISTRATION

ClinicalTrials.gov, no. NCT04510623.

Seroprevalence of SARS-CoV-2 antibodies among primary healthcare workers in the Republic of Srpska, Bosnia & Herzegovina: A cross-sectional study

Healthcare workers (HCW) in primary healthcare centres in the Republic of Srpska, Bosnia and Herzegovina, are on the first combat line with COVID-19. This study aimed to assess the seroprevalence of SARS-CoV-2 among HCW at the primary healthcare centres and to analyse the risk exposure to COVID-19, clinical signs and vaccination status. A cross-sectional study was conducted among HCW at the selected primary healthcare centres between 19 March and 30 April 2021. Antibodies against the SARS-CoV-2 virus were detected by enzyme-linked immunosorbent assay (ELISA). A total of 1,023 HCW (mean age 45 years; 71% female) were included in the study. The anti-SARS-CoV-2 antibodies were detected in 69.5% of all participants. There was a significant difference in seropositivity among primary healthcare centres from different geographical regions. As many as 432 (42%) of all participants had confirmed COVID-19 symptoms before the study and, 84.8% of them were seropositive. This study showed that 702 primary HCW were vaccinated with any of these vaccines: Sputnik V, Sinopharm, Pfizer/Biontech. High titre of SARS-CoV-2 antibodies was found amongst those who received one (92.6%) or both (97.2%) doses of vaccines. In this study, we report high prevalence of SARS-CoV-2 antibody among HCW in primary healthcare in the Republic of Srpska, Bosnia and Herzegovina during the third pandemic wave.

Assessment of Diagnostic Specificity of Anti-SARS-CoV-2 Antibody Tests and Their Application for Monitoring of Seroconversion and Stability of Antiviral Antibody Response in Healthcare Workers in Moscow

Anti-SARS-CoV-2 antibody testing is an efficient tool to assess the proportion of seropositive population due to infection and/or vaccination. Numerous test systems utilizing various antigen composition(s) are routinely used for detection and quantitation of anti-SARS-CoV-2 antibodies. We determined their diagnostic specificity using archived true-negative samples collected before the onset of the COVID-19 pandemic. Using test systems demonstrating 98.5-100% specificity, we assessed the dynamics of SARS-CoV-2 seroconversion and durability of anti-spike (S) antibodies in healthcare professionals (n = 100) working in Moscow during the first two cycles of the pandemic (May 2020 to June 2021) outside of the "red zone". Analysis revealed a rapid increase in anti-SARS-CoV-2 seropositivity from 19 to 80% (19/100 and 80/100, respectively) due to virus exposition/infection; only 16.3% of seroconversion cases (13/80) were due to vaccination, but not the virus exposure, although massive COVID-19 vaccination of healthcare workers was performed beginning in December 2020. In total, 12.7% (8/63) remained positive for anti-SARS-CoV-2 IgM for >6 months, indicating unsuitability of IgM for identification of newly infected individuals. All except one remained seropositive for anti-S antibodies for >9 months on average. Significant (>15%) declines in anti-SARS-CoV-2 antibody concentrations were observed in only 18% of individuals (9/50). Our data on the high seropositivity rate and stability of anti-SARS-CoV-2 antibody levels in healthcare personnel working outside of the "red zone" indicate their regular exposition to SARS-CoV-2/an increased risk of infection, while a low frequency of vaccine-induced antibody response acquired after the start of vaccination points to vaccine hesitancy.

Seroprevalence of anti-SARS-CoV-2 antibodies among staff at primary healthcare institutions in Prishtina

BACKGROUND

Many studies examined the spread of SARS-CoV-2 within populations using seroprevalence. Healthcare workers are a high-risk population due to patient contact, and studies are needed to examine seroprevalence of SARS-CoV-2 antibodies among healthcare workers. Our study investigates the seroprevalence of anti-SARS-CoV-2 antibodies among staff at primary healthcare institutions in Prishtina, and factors associated with seroprevalence.

METHODS

We carried out a cross-sectional survey including SARS-CoV-2 serological testing and questionnaires with primary healthcare workers from primary healthcare facilities in the Prishtina, the capital city of Kosovo. We calculated prevalence of anti-SARS-CoV-2 antibodies, and of self-reported positive PCR test among primary healthcare workers, as well as crude and adjusted ORs for explanatory factors.

RESULTS

Eighty-three of the healthcare workers (17.47%) tested positive for SARS-CoV-2 antibodies IgG or IgM, while 231 (48.63%) either had antibodies or a previous positive PCR test. Odds of seropositivity were affected by male gender (OR 2.08, 95% CI 1.20, 3.61), and infected family members (OR 3.61, 95% CI 2.25, 5.79) of healthcare workers. Higher education, being part of larger families and having infected family members gave higher odds of positive PCR test and seropositivity. Other healthcare workers had lower odds of positive PCR test and seropositivity than physicians.

CONCLUSION

Over 17% of healthcare workers were seropositive for SARS-CoV-2 antibodies and close to half of them were either seropositive or PCR self-reported positive test. Several factors are associated with decreased and increased odds for such outcomes. These findings should be explored further and addressed to Kosovo policy makers, and assist them to intensify vaccination efforts, and maintain control measures until we achieve herd immunity.

Evaluation of a support system for health professionals confined by COVID-19

OBJECTIVE

To evaluate the implementation of a telephone system in a department of Primary Care in Barcelona, Spain, supporting health professionals confined by COVID-19.

METHODS

We conducted an observational, descriptive, cross-sectional study with confined professionals, between March 11 and May 31, 2020. We emailed a questionnaire with 18 closed-ended questions and one open-ended question and performed a descriptive analysis of the closed-ended answers and an analysis of the thematic content of the open-ended question.

RESULTS

Thirty-nine hundred and ninety-eight professionals evaluated the system overall with a score of 6.54 on a scale of 1 to 10. The evaluation of the format of calls made in the support system had higher scores, while the psychological support unit and the coordination of the different groups had lower scores. The content analysis of the open-ended question provides explanatory arguments for the quantitative results.

CONCLUSIONS

The study allowed a valid and reliable evaluation of the implementation of a support system for confined professionals, in addition to recognizing areas for improvement.

SARS-CoV-2 seroprevalence in health care workers from 10 hospitals in Quebec, Canada: a cross-sectional study

BACKGROUND

The COVID-19 pandemic has disproportionately affected health care workers. We sought to estimate SARS-CoV-2 seroprevalence among hospital health care workers in Quebec, Canada, after the first wave of the pandemic and to explore factors associated with SARS-CoV-2 seropositivity.

METHODS

Between July 6 and Sept. 24, 2020, we enrolled health care workers from 10 hospitals, including 8 from a region with a high incidence of COVID-19 (the Montréal area) and 2 from low-incidence regions of Quebec. Eligible health care workers were physicians, nurses, orderlies and cleaning staff working in 4 types of care units (emergency department, intensive care unit, COVID-19 inpatient unit and non-COVID-19 inpatient unit). Participants completed a questionnaire and underwent SARS-CoV-2 serology testing. We identified factors independently associated with higher seroprevalence.

RESULTS

Among 2056 enrolled health care workers, 241 (11.7%) had positive SARS-CoV-2 serology. Of these, 171 (71.0%) had been previously diagnosed with COVID-19. Seroprevalence varied among hospitals, from 2.4% to 3.7% in low-incidence regions to 17.9% to 32.0% in hospitals with outbreaks involving 5 or more health care workers. Higher seroprevalence was associated with working in a hospital where outbreaks occurred (adjusted prevalence ratio 4.16, 95% confidence interval [CI] 2.63-6.57), being a nurse or nursing assistant (adjusted prevalence ratio 1.34, 95% CI 1.03-1.74) or an orderly (adjusted prevalence ratio 1.49, 95% CI 1.12-1.97), and Black or Hispanic ethnicity (adjusted prevalence ratio 1.41, 95% CI 1.13-1.76). Lower seroprevalence was associated with working in the intensive care unit (adjusted prevalence ratio 0.47, 95% CI 0.30-0.71) or the emergency department (adjusted prevalence ratio 0.61, 95% CI 0.39-0.98).

INTERPRETATION

Health care workers in Quebec hospitals were at high risk of SARS-CoV-2 infection, particularly in outbreak settings. More work is needed to better understand SARS-CoV-2 transmission dynamics in health care settings.

SARS-CoV-2 seroprevalence in health care workers from 10 hospitals in Quebec, Canada: a cross-sectional study

BACKGROUND

The COVID-19 pandemic has disproportionately affected health care workers. We sought to estimate SARS-CoV-2 seroprevalence among hospital health care workers in Quebec, Canada, after the first wave of the pandemic and to explore factors associated with SARS-CoV-2 seropositivity.

METHODS

Between July 6 and Sept. 24, 2020, we enrolled health care workers from 10 hospitals, including 8 from a region with a high incidence of COVID-19 (the Montréal area) and 2 from low-incidence regions of Quebec. Eligible health care workers were physicians, nurses, orderlies and cleaning staff working in 4 types of care units (emergency department, intensive care unit, COVID-19 inpatient unit and non-COVID-19 inpatient unit). Participants completed a questionnaire and underwent SARS-CoV-2 serology testing. We identified factors independently associated with higher seroprevalence.

RESULTS

Among 2056 enrolled health care workers, 241 (11.7%) had positive SARS-CoV-2 serology. Of these, 171 (71.0%) had been previously diagnosed with COVID-19. Seroprevalence varied among hospitals, from 2.4% to 3.7% in low-incidence regions to 17.9% to 32.0% in hospitals with outbreaks involving 5 or more health care workers. Higher seroprevalence was associated with working in a hospital where outbreaks occurred (adjusted prevalence ratio 4.16, 95% confidence interval [CI] 2.63-6.57), being a nurse or nursing assistant (adjusted prevalence ratio 1.34, 95% CI 1.03-1.74) or an orderly (adjusted prevalence ratio 1.49, 95% CI 1.12-1.97), and Black or Hispanic ethnicity (adjusted prevalence ratio 1.41, 95% CI 1.13-1.76). Lower seroprevalence was associated with working in the intensive care unit (adjusted prevalence ratio 0.47, 95% CI 0.30-0.71) or the emergency department (adjusted prevalence ratio 0.61, 95% CI 0.39-0.98).

INTERPRETATION

Health care workers in Quebec hospitals were at high risk of SARS-CoV-2 infection, particularly in outbreak settings. More work is needed to better understand SARS-CoV-2 transmission dynamics in health care settings.

SARS-CoV-2 IgG seropositivity in a cohort of 449 non-hospitalized individuals during Spanish COVID-19 lockdown

The Coronavirus Disease of 2019 (COVID-19) pandemic caused by SARS-CoV-2 led the Spanish government to impose a national lockdown in an attempt to control the spread of the infection. Mobility restrictions and the requirement of a medical prescription for serological testing for COVID-19 were included among the control measures. Under this scenario, between April 15th and June 15th, 2020, we performed an observational study including 449 individuals allowed to be tested according to the governmental restrictions, i.e. fulfilling the following prescription requirements: manifestation of COVID-19-compatible symptoms, contact with a confirmed COVID-19 patient, or employment as an essential worker, including health care workers, firefighters and public safety personnel such as police. Importantly, a relevant feature of the studied cohort was that none of the participants had been hospitalized. We analyzed SARS-CoV-2 IgG seropositivity in this specific cohort, uncovering intrinsic features of great demographic interest. The overall rate of IgG seropositivity was 33.69% (95% CI: 29.27-38.21). This frequency was comparable among the different participant occupations. A RT-PCR positive test, contact with a household member previously tested positive and the presence of COVID-19-compatible symptoms were positively associated with IgG + results. Among these symptoms, ageusia/anosmia was positively and independently associated with SARS-CoV-2 IgG seropositivity, while odynophagia was inversely associated. However, fever, ageusia/anosmia and asthenia were the most frequent symptoms described by IgG + subjects. Therefore, our data illustrate how specific cohorts display particular characteristics that should be taken into account when studying population-wide SARS-CoV-2 seroprevalence and key defining symptoms of COVID-19.

The seroprevalence of SARS-CoV-2 during the first wave in Europe 2020: A systematic review

BACKGROUND

A year following the onset of the COVID-19 pandemic, new infections and deaths continue to increase in Europe. Serological studies, through providing evidence of past infection, can aid understanding of the population dynamics of SARS-CoV-2 infection.

OBJECTIVES

This systematic review of SARS-CoV-2 seroprevalence studies in Europe was undertaken to inform public health strategies including vaccination, that aim to accelerate population immunity.

METHODS

We searched the databases Web of Science, MEDLINE, EMBASE, SCOPUS, Cochrane Database of Systematic Reviews and grey literature sources for studies reporting seroprevalence of SARS-CoV-2 antibodies in Europe published between 01/12/2019-30/09/20. We provide a narrative synthesis of included studies. Studies were categorized into subgroups including healthcare workers (HCWs), community, outbreaks, pregnancy and children/school. Due to heterogeneity in other subgroups, we only performed a random effects meta-analysis of the seroprevalence amongst HCWs stratified by their country.

RESULTS

115 studies were included spanning 17 European countries, that estimated the seroprevalence of SARS-CoV-2 from samples obtained between November 2019 -August 2020. A total of 54/115 studies included HCWs with a reported seroprevalence among HCWs ranging from 0.7% to 45.3%, which did not differ significantly by country. In community studies significant heterogeneity was reported in the seroprevalence between different age groups and the majority of studies reported there was no significant difference by gender.

CONCLUSION

This review demonstrates a wide heterogeneity in reported seroprevalence of SARS-CoV-2 antibodies between populations. Continued evaluation of seroprevalence is required to understand the impact of public health measures and inform interventions including vaccination programmes.

High class filtering facepiece (FFP) are fundamental and effective in protection of emergency health care workers: an observational cohort study in a German community

Background

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a highly contagious airborne virus inducing pandemic coronavirus disease 2019 (COVID-19). This is most relevant for medical staff working under harmful conditions in emergencies often dealing with patients and an undefined SARS-CoV-2 status. We aimed to measure the effect of high-class filtering facepieces (FFP) in emergency medical service (EMS) staff by analyzing seroprevalence and history of positive polymerase chain reaction (PCR) for SARS-CoV-2.

Method

This observational cohort study included workers in EMS, who were compared with hospital staff (HS) and staff, which was not directly involved in patient care (NPC). All direct patient contacts of EMS workers were protected by FFP2/N95 (filtering face piece protection class 2/non-oil-based particulates filter efficiency 95%) masks, whereas HS was protected by FFP2/N95 exclusively when a patient had a proven or suspected SARS-CoV-2 infection. NPC was not protected by higher FFP. The seroprevalence of SARS-CoV-2 antibodies was analyzed by immunoassay by end of 12/2020 together with the history of a positive PCR. In addition, a self-assessment was performed regarding the quantity of SARS-CoV-2 positive contacts, about flu symptoms and personal belief of previous COVID-19 infections.

Results

The period in which contact to SARS-CoV-2 positive patients has been possible was 10 months (March to December 2020)—with 54,681 patient contacts documented for EMS—either emergencies (n = 33,241) or transportation services (n = 21,440). Seven hundred-thirty (n = 730) participants were included into the study (n = EMS: 325, HS: 322 and NPC: 83). The analysis of the survey showed that the exposure to patients with an unknown and consecutive positive SARS-CoV-2 result was significantly higher for EMS when compared to HS (EMS 55% vs. HS 30%, p = 0.01). The incidence of a SARS-CoV-2 infection in our cohort was 1.2% (EMS), 2.2% (HS) and 2.4% (NPC) within the three groups (ns) and lowest in EMS. Furthermore, the belief of previous COVID-19 was significant higher in EMS (19% vs. 10%),

Conclusion

The consistent use of FFP2/N95 in EMS is able to prevent work-related SARS-CoV-2 infections in emergency situations. The significance of physical airway protection in exposed medical staff is still relevant especially under the aspect of new viral variants and unclear effectiveness of new vaccines.

Graphical Abstract

Discrepancy between frequent occurrence of COVID-19-like symptoms and low seroconversion rates among healthcare workers

During the first wave of the pandemic, we compared the occurrence of subjectively experienced COVID‐19‐like symptoms and true severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) seroconversion rates among medical personnel in general practices. This cross‐sectional study determined the SARS‐CoV‐2‐specific immunoglobulin G (IgG) antibody status of medical staff from 100 outpatient practices in Germany. Study cohort characteristics and COVID‐19‐like symptoms were obtained by questionnaires. The initial screening for SARS‐CoV‐2‐recognizing antibodies was performed using a commercial chemiluminescence microparticle immunoassay. Positive results were controlled with another approved test. Samples with discrepant results were subjected to a third IgG‐binding assay and a neutralization test. A total of 861 participants were included, 1.7% (n = 15) of whom tested positive for SARS‐CoV‐specific IgG in the initial screening test. In 46.6% (n = 7) of positive cases, test results were confirmed by an independent test. In the eight samples with discrepant results, neither spike‐specific antibodies nor in vitro neutralizing capacity were detectable, resulting in a genuine seroprevalence rate of 0.8%. 794 participants completed the questionnaire. Intriguingly, a total of 53.7% (n = 426) of them stated episodes of COVID‐19‐like symptoms. Except for smell and taste dysfunction, there were no significant differences between the groups with and without laboratory‐confirmed SARS‐CoV‐2 seroconversion. Our results demonstrated that only 0.8% of participants acquired SARS‐CoV‐2 even though 53.7% of participants reportedly experienced COVID‐19‐like symptoms. Thus, even among medical staff, self‐diagnosis based on subjectively experienced symptoms does not have a relevant predictive value.

Prevalence of SARS-CoV-2 antibodies among nurses: A systematic review and meta-analysis

Aims and Objectives

This systematic review and meta‐analysis reports the seroprevalence of SARS‐CoV‐2 antibodies among nurses.

Background

With a growing body of literature reporting the positive serology for SARS‐CoV‐2 antibodies among healthcare workers, it remains unclear whether staff at the point of direct patient care are more prone to developing and transmitting the virus. Given nurses make up the majority of the global health workforce, outbreaks among these workers could severely undermine a health system’s capability to manage the pandemic. We aimed to summarise and report the seroprevalence of SARS‐CoV‐2 antibodies among nurses globally.

Design

Systematic review and meta‐analyses.

Methods

This systematic review was developed, undertaken and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guideline. We searched the electronic medical literature databases: MEDLINE; CINAHL; and EMBASE for studies reporting the seroprevalence of SARS‐CoV‐2 antibodies among nursing staff. Studies that reported nursing specific data were included in this review. Study quality was evaluated using the Joanna Briggs Institute checklist for studies reporting prevalence data. Studies were stratified according to the World Health Organisation region classifications, and results were presented using forest plots and summary prevalence and variance was estimated using a random effects model.

Results

Our electronic search identified 1687 potential studies, of which 1148 were screened for eligibility after duplicates were removed, and 51 of the studies were included in our meta‐analysis. The overall seroprevalence of SARS‐CoV‐2 antibodies among nurses was estimated to be 8.1% (95% CI 6.9%–9.4%) among the 60,571 participants included in the studies. Seropositivity was highest in the African region (48.2%, 95% CI 39.2%–57.3%), followed by the European region (10.3%, 95% CI 8.0%–12.5%), the Region of the Americas (8.4%, 95% CI 6.0%–10.7%), the South‐East Asia region (3.0%, 95% CI 0.00%–6.5%) and the Western Pacific region (0.5%, 95% CI 0.0%–1.0%). Pooled estimates were unable to be calculated in the Eastern Mediterranean region due to insufficient studies.

Conclusion

The seroprevalence of SARS‐CoV‐2 antibodies among nurses is comparable to other healthcare workers, and possibly similar to the general population. Early adoption and adherence to personal protective equipment and social distancing measures could explain these similarities, meaning the majority of staff contracted the virus through community transmission and not in a healthcare setting.

Relevance to clinical practice

Fear and uncertainty have been features of this pandemic, including among nurses. This meta‐analysis should provide some comfort to nurses that risks are similar to community exposure when adequate PPE is available and there is an adherence to infection control measures.

Seven-month kinetics of SARS-CoV-2 antibodies and role of pre-existing antibodies to human coronaviruses

Unraveling the long-term kinetics of antibodies to SARS-CoV-2 and the individual characteristics influencing it, including the impact of pre-existing antibodies to human coronaviruses causing common cold (HCoVs), is essential to understand protective immunity to COVID-19 and devise effective surveillance strategies. IgM, IgA and IgG levels against six SARS-CoV-2 antigens and the nucleocapsid antigen of the four HCoV (229E, NL63, OC43 and HKU1) were quantified by Luminex, and antibody neutralization capacity was assessed by flow cytometry, in a cohort of health care workers followed up to 7 months (N = 578). Seroprevalence increases over time from 13.5% (month 0) and 15.6% (month 1) to 16.4% (month 6). Levels of antibodies, including those with neutralizing capacity, are stable over time, except IgG to nucleocapsid antigen and IgM levels that wane. After the peak response, anti-spike antibody levels increase from ~150 days post-symptom onset in all individuals (73% for IgG), in the absence of any evidence of re-exposure. IgG and IgA to HCoV are significantly higher in asymptomatic than symptomatic seropositive individuals. Thus, pre-existing cross-reactive HCoVs antibodies could have a protective effect against SARS-CoV-2 infection and COVID-19 disease.

The front-line during the coronavirus disease 2019 pandemic: healthcare personnel

PURPOSE OF REVIEW

An estimated four to 11% of reported coronavirus disease 2019 (COVID-19) cases occurs in healthcare personnel (HCP). HCP are at high risk of acquiring and transmitting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) given their close contact with individuals with recognized and unrecognized COVID-19. We summarize the literature to date describing the epidemiology, identifying risk factors associated with COVID-19, and analyzing clinical characteristics and outcomes of SARS-CoV-2 infection in HCP.

RECENT FINDINGS

The prevalence of SARS-CoV-2 antibodies among HCP ranges from 0.7 to 45%. Although there is heterogeneity in the seroprevalence rate reported in the literature, HCP may be at increased risk of SARS-CoV-2 infection from exposure to patients with COVID-19. The literature supports that this can be minimized with adequate personal protective equipment (PPE) supply, proper hand hygiene, appropriate PPE use, and other infection prevention measures. In addition, infections in HCP are commonly acquired in the community as well as in nonclinical care settings including break rooms or work rooms.

SUMMARY

While much focus has been on minimizing patient-to-HCP transmission of SARS-CoV-2, additional efforts are needed to prevent exposures in nonclinical care settings and in the community.

Seroprevalence of SARS-CoV-2 IgG antibodies among health care workers prior to vaccine administration in Europe, the USA and East Asia: A systematic review and meta-analysis

BACKGROUND

Knowing the seroprevalence of SARS-CoV-2 IgG antibodies across geographic regions before vaccine administration is one key piece of knowledge to achieve herd immunity. While people of all ages, occupations, and communities are at risk of getting infected with SARS-CoV-2, the health care workers (HCWs) are possibly at the highest risk. Most seroprevalence surveys with HCWs conducted worldwide have been limited to Europe, North America, and East Asia. We aimed to understand how the seroprevalence of SARS-CoV-2 IgG antibodies varied across these geographic regions among HCWs based on the available evidences.

METHODS

By searching through PubMed, ScienceDirect, and Google Scholar databases, eligible studies published from January 1, 2020 to January 15, 2021 were included for the systematic review and meta-analysis. The random-effects model was used to estimate the pooled proportion of IgG seropositive HCWs. Publication bias was assessed by funnel plot and confirmed by Egger's test. Heterogeneity was quantified using I2 statistics. We performed sensitivity analyses based on sample size, diagnostic method and publication status. The study protocol was registered with PROSPERO (CRD42020219086).

FINDINGS

A total of 53 peer-reviewed articles were selected, including 173,353 HCWs (32.7% male) from the United States, ten European, and three East Asian countries. The overall seropositive prevalence rate of IgG antibodies was 8.6% in these regions (95% CI= 7.2-9.9%). Pooled seroprevalence of IgG antibodies was higher in studies conducted in the USA (12.4%, 95% CI= 7.8-17%) than in Europe (7.7%, 95% CI=6.3-9.2%) and East Asia (4.8%, 95% CI=2.9-6.7%). The subgroup study also estimated that male HCWs had 9.4% (95% CI= 7.2-11.6%) IgG seroconversion, and female HCWs had 7.8% (95% CI=5.9-9.7%). The study exhibits a high prevalence of IgG antibodies among HCWs under 40 years in the USA, conversely, it was high in older HCWs (≥40 years of age) in Europe and East Asia. In the months February-April 2020, the estimated pooled seroprevalence was 5.7% (4.0-7.4%) that increased to 8·2% (6.2-10%) in April-May and further to 9.9% (6.9-12.9%) in the May-September time-period.

INTERPRETATION

In the view of all evidence to date, a significant variation in the prevalence of SARS-CoV-2 antibodies in HCWs is observed in regions of Europe, the United States, and East Asia. The patterns of IgG antibodies by time, age, and gender suggest noticeable regional differences in transmission of the virus. Based on the insights driven from the analysis, priority is required for effective vaccination for older HCWs from Europe and East Asia. A considerable high seroprevalence of IgG among HCWs from the USA suggests a high rate of past infection that indicates the need to take adequate measures to prevent hospital spread. Moreover, the seroprevalence trend was not substantially changed after May 2020, suggesting a slow progression of long-term SARS-CoV-2 immunity. Routine testing of HCWs for SARS-CoV-2 should be considered even after the rollout of vaccination to identify the areas of increased transmission.

FUNDING

None.

Seroprevalence of antibodies against SARS-CoV-2 among health care workers in a pediatric monographic hospital in Madrid (Spain)

INTRODUCTION

As of 30 April 2020, 203.715 SARS-CoV-2 infections had been reported in Spain, 54.486 in Madrid, 21.4% were health care workers. Our objective is to determine seroprevalence of COVID-19 among workers in a monographic pediatric hospital.

METHODS

Between April13th and 30th, 1.523 health workers were recruited to be tested for SARS-CoV-2 serology screening (All Test®) and they answered a questionnaire with demographic, epidemiological and clinical information and previous exposure to COVID-19.

FINDINGS

One thousand two hundred ninety two (84.8%) were tested. Positive serology (IgM and/or IgG) to SARS-CoV-2 was found in 17.2% (222/1.292), in 15.5% (201/1.292) if only IgG was considered. Median age was 44±13 years, 73% were female. The 33.8% (75/222) were asymptomatic. Eighty one had a previous positive rRT-PCR. The 14% (32/222) referred a family contact.

CONCLUSION

Serology prevalence for SARS-CoV-2 in workers of a pediatric hospital was higher than in general population. Many of them had an unnoticed infection.