Seroprevalence of SARS-CoV-2 Among Frontline Healthcare Personnel During the First Month of Caring for Patients With COVID-19-Nashville, Tennessee

Serosurveillance of COVID-19 amongst health care workers in a teaching institution - A prospective cohort study in Puducherry district

Introduction

The rapid spread and mutation rate of severe acute respiratory syndrome corona virus (SARS-CoV2) demands continuous monitoring in terms of genomic and serosurvival. The current study is designed to track the seroprevalence of health care workers (HCWs) postvaccination, as they may be more susceptible to contracting the SARS-CoV-2 infection compared to the general population.

Objective

The objective was to identify the seroprevalence rate for SARS-CoV-2 immunoglobulin G (IgG) antibody (N, S1, S2) amongst HCWs of various levels of exposure working in a tertiary care teaching hospital in Puducherry.

Materials and Methods

The present study followed a nonprobability consecutive sampling technique, which involved 216 study participants HCWs from the hospital. IgG antibody levels were measured using EUROIMMUNE Anti SARS-COV-2 ELISA KIT (IG g) ELISA at two points: firstly, 2 weeks after the second dose of vaccination, followed by 2 weeks after the booster dose.

Results

Out of the total 216 participants enrolled in the survey, there were 140 males and 76 females, and the maximum number of candidates studied were in the 41-50 age group. Almost 46.7% of the HCWs who participated in the study were seropositive for SARS-CoV-2 in the case of those who were high-risk exposed, while only 30.4% were amongst those who were low-risk exposed. The proportion of study participants who became seropositive increased considerably after the booster dose (65.7%), from 38.0% when tested three months after infection.

Conclusion

A significant increase in antibody titres amongst high-risk HCWs postboost vaccination demands continuous monitoring of soluble IgG levels for recommendations of vaccination schedules.

Seroprevalence of SARS-CoV-2 in Niger State: Pilot Cross-Sectional Study

Background

The COVID-19 pandemic caused by SARS-CoV-2 is causing ongoing human and socioeconomic losses.

Objective

To know how far the virus has spread in Niger State, Nigeria, a pilot study was carried out to determine the SARS-CoV-2 seroprevalence, patterns, dynamics, and risk factors in the state.

Methods

A cross-sectional study design and clustered, stratified random sampling strategy were used to select 185 test participants across the state. SARS-CoV-2 IgG and IgM rapid test kits (colloidal gold immunochromatography lateral flow system) were used to determine the presence or absence of antibodies to the virus in the blood of sampled participants across Niger State from June 26 to 30, 2020. The test kits were validated using the blood samples of some of the Nigeria Center for Disease Control-confirmed positive and negative COVID-19 cases in the state. SARS-CoV-2 IgG and IgM test results were entered into the Epi Info questionnaire administered simultaneously with each test. Epi Info was then used to calculate the arithmetic mean and percentage, odds ratio, χ2 statistic, and regression at a 95% CI of the data generated.

Results

The seroprevalence of SARS-CoV-2 in Niger State was found to be 25.4% (47/185) and 2.2% (4/185) for the positive IgG and IgM results, respectively. Seroprevalence among age groups, genders, and occupations varied widely. The COVID-19 asymptomatic rate in the state was found to be 46.8% (22/47). The risk analyses showed that the chances of infection are almost the same for both urban and rural dwellers in the state. However, health care workers, those who experienced flulike symptoms, and those who had contact with a person who traveled out of Nigeria in the last 6 months (February to June 2020) were at double the risk of being infected with the virus. More than half (101/185, 54.6%) of the participants in this study did not practice social distancing at any time since the pandemic started. Participants' knowledge, attitudes, and practices regarding COVID-19 are also discussed.

Conclusions

The observed Niger State SARS-CoV-2 seroprevalence and infection patterns meansuggest that the virus has widely spread, far more SARS-CoV-2 infections have occurred than the reported cases, and there is a high asymptomatic COVID-19 rate across the state.

Risk factors for SARS-CoV-2 seropositivity in a health care worker population during the early pandemic

BACKGROUND

While others have reported severe acute respiratory syndrome-related coronavirus 2(SARS-CoV-2) seroprevalence studies in health care workers (HCWs), we leverage the use of a highly sensitive coronavirus antigen microarray to identify a group of seropositive health care workers who were missed by daily symptom screening that was instituted prior to any epidemiologically significant local outbreak. Given that most health care facilities rely on daily symptom screening as the primary method to identify SARS-CoV-2 among health care workers, here, we aim to determine how demographic, occupational, and clinical variables influence SARS-CoV-2 seropositivity among health care workers.

METHODS

We designed a cross-sectional survey of HCWs for SARS-CoV-2 seropositivity conducted from May 15th to June 30th 2020 at a 418-bed academic hospital in Orange County, California. From an eligible population of 5,349 HCWs, study participants were recruited in two ways: an open cohort, and a targeted cohort. The open cohort was open to anyone, whereas the targeted cohort that recruited HCWs previously screened for COVID-19 or work in high-risk units. A total of 1,557 HCWs completed the survey and provided specimens, including 1,044 in the open cohort and 513 in the targeted cohort. Demographic, occupational, and clinical variables were surveyed electronically. SARS-CoV-2 seropositivity was assessed using a coronavirus antigen microarray (CoVAM), which measures antibodies against eleven viral antigens to identify prior infection with 98% specificity and 93% sensitivity.

RESULTS

Among tested HCWs (n = 1,557), SARS-CoV-2 seropositivity was 10.8%, and risk factors included male gender (OR 1.48, 95% CI 1.05-2.06), exposure to COVID-19 outside of work (2.29, 1.14-4.29), working in food or environmental services (4.85, 1.51-14.85), and working in COVID-19 units (ICU: 2.28, 1.29-3.96; ward: 1.59, 1.01-2.48). Amongst 1,103 HCWs not previously screened, seropositivity was 8.0%, and additional risk factors included younger age (1.57, 1.00-2.45) and working in administration (2.69, 1.10-7.10).

CONCLUSION

SARS-CoV-2 seropositivity is significantly higher than reported case counts even among HCWs who are meticulously screened. Seropositive HCWs missed by screening were more likely to be younger, work outside direct patient care, or have exposure outside of work.

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.

Guidelines for Infection Control and Burnout Prevention in Healthcare Workers Responding to COVID-19

During the coronavirus disease 2019 (COVID-19) pandemic, frontline healthcare workers (HCWs) suffered more distress from the possibility of contracting the virus, quarantine, social stigma, and prejudice against their families. Many studies have investigated the impact of the pandemic on HCWs; however, studies or guidelines presenting strategies to overcome these challenges are lacking. As part of a 2020 research project supported by the Ministry of Health and Welfare, titled "Health impact assessment of healthcare workers undertaking coronavirus disease 2019 treatment and management in Korea: Identifying problems and researching effective solutions" (HC20C0003), we created guidelines to respond to serious problems posed by infection control. and burnout among HCWs during COVID-19 response measures throughout the extended pandemic period. We formulated the guidelines by means of a systematic review and collated them with the latest literature. The guidelines will highlight the gravity and impact of infection control and burnout among HCWs responding to COVID-19 and include potential prevention strategies, and they can be used as a reference in the event of another emerging infectious disease outbreak in the future.

Missing science: A scoping study of COVID-19 epidemiological data in the United States

Systematic approaches to epidemiologic data collection are critical for informing pandemic responses, providing information for the targeting and timing of mitigations, for judging the efficacy and efficiency of alternative response strategies, and for conducting real-world impact assessments. Here, we report on a scoping study to assess the completeness of epidemiological data available for COVID-19 pandemic management in the United States, enumerating authoritative US government estimates of parameters of infectious transmission, infection severity, and disease burden and characterizing the extent and scope of US public health affiliated epidemiological investigations published through November 2021. While we found authoritative estimates for most expected transmission and disease severity parameters, some were lacking, and others had significant uncertainties. Moreover, most transmission parameters were not validated domestically or re-assessed over the course of the pandemic. Publicly available disease surveillance measures did grow appreciably in scope and resolution over time; however, their resolution with regards to specific populations and exposure settings remained limited. We identified 283 published epidemiological reports authored by investigators affiliated with U.S. governmental public health entities. Most reported on descriptive studies. Published analytic studies did not appear to fully respond to knowledge gaps or to provide systematic evidence to support, evaluate or tailor community mitigation strategies. The existence of epidemiological data gaps 18 months after the declaration of the COVID-19 pandemic underscores the need for more timely standardization of data collection practices and for anticipatory research priorities and protocols for emerging infectious disease epidemics.

Prevalence and Clinical Presentation of COVID 19 in Health Care Workers in Two Main Hospitals During the Pandemic in Shiraz, Iran

Background: Given that immunocompromised patients are more at risk for the infection of SARS-CoV-2, epidemiological data are critical for assessing the corresponding prevalence among health care workers (HCWs) and patients at health centers. Objectives: This study aims to investigate the prevalence of SARS-CoV-2 infection among the staff of two hospitals that take care of immunocompromised patients, including pediatrics and adults with special medical conditions. Methods: This cross-sectional study includes all HCWs of the two hospitals; Abu Ali Sina Transplant Hospital (AASTH) and Amir al-Momenin Burn Injury Hospital (AABIH) in Shiraz, southern Iran, conducted from April 11, 2020, to June 16, 2021. The TaqMan real-time PCR assay was used to assess the SARS-CoV-2 infection rate in the suspected HCWs. Results: Out of 1232 sampled HCWs, 694 (56%) were female. Two hundred sixty-five samples (21.5%) and 967 samples (78.5%) were prepared from AABIH, and AASTH, respectively. The results showed that 30% (373) of the clinically suspected employees had positive test results. There was a significant correlation between the risk of exposure to COVID-19 patients and the PCR positivity rate, which could be explained by the fact that 58% of the infected HCWs were in a high-risk group, 20% medium-risk, and the remaining 22% were low-risk (P < 0.0001). The rates of positive cases in females were higher than that among male counterparts (P < 0.05). Conclusions: In order to protect health care workers and reduce the prevalence and transmission of diseases, deficiencies must be identified and eliminated.

Real-world impact of vaccination on coronavirus disease 2019 (COVID-19) incidence in healthcare personnel at an academic medical center

OBJECTIVE

Coronavirus disease 2019 (COVID-19) vaccination effectiveness in healthcare personnel (HCP) has been established. However, questions remain regarding its performance in high-risk healthcare occupations and work locations. We describe the effect of a COVID-19 HCP vaccination campaign on SARS-CoV-2 infection by timing of vaccination, job type, and work location.

METHODS

We conducted a retrospective review of COVID-19 vaccination acceptance, incidence of postvaccination COVID-19, hospitalization, and mortality among 16,156 faculty, students, and staff at a large academic medical center. Data were collected 8 weeks prior to the start of phase 1a vaccination of frontline employees and ended 11 weeks after campaign onset.

RESULTS

The COVID-19 incidence rate among HCP at our institution decreased from 3.2% during the 8 weeks prior to the start of vaccinations to 0.38% by 4 weeks after campaign initiation. COVID-19 risk was reduced among individuals who received a single vaccination (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.40-0.68; P < .0001) and was further reduced with 2 doses of vaccine (HR, 0.17; 95% CI, 0.09-0.32; P < .0001). By 2 weeks after the second dose, the observed case positivity rate was 0.04%. Among phase 1a HCP, we observed a lower risk of COVID-19 among physicians and a trend toward higher risk for respiratory therapists independent of vaccination status. Rates of infection were similar in a subgroup of nurses when examined by work location.

CONCLUSIONS

Our findings show the real-world effectiveness of COVID-19 vaccination in HCP. Despite these encouraging results, unvaccinated HCP remain at an elevated risk of infection, highlighting the need for targeted outreach to combat vaccine hesitancy.

Seroprevalence of Anti-SARS-CoV-2 Antibodies in High-Risk Occupational and Low-Risk Groups in Southwestern Iran

Background: Monitoring the spread of SARS-CoV-2 has been considered by the World Health Organization (WHO). We examined the prevalence of anti-SARS-CoV-2 immunoglobulin antibodies in southwestern Iran in spring 2020. The circulation of SARS-CoV-2 is high in the general population, especially among health care workers (HCWs) who are in close contact with patients. Objectives: The aim of this study was to determine the prevalence of anti-SARS-CoV-2 antigen in high-risk occupational and low-risk groups to investigate risk factors for serum positivity in Shiraz, southwestern Iran. Methods: A cross-sectional survey was performed on 366 participants (204 from high-risk and 162 from low-risk subjects). IgG and IgM antibodies were detected using Pishtaz Teb COVID-19 ELISA Kits to evaluate SARS-CoV-2-antigen in serum samples. After enzyme-linked immunosorbent assay (ELISA), serum prevalence, as well as IgG/IgM positive factors, was determined using logistic regression. Results: From July to September 2020 (a few months after reporting the first case of COVID-19 cases in Iran), out of 366 survived people, 72 (40.9%) were IgG positive, and 50 (27.5%) were IgM positive. The frequency of positive serology for IgG and IgM antibodies in individuals aged < 30 years was higher in the low-risk group than in the high-risk group. Multivariate logistic regression showed that headache (OR 0.312 [95% CI: 0.136 - 0.717]) and cough (OR 0.427 [95% CI: 0.182 - 1.004]) factors were associated with IgG or IgM positive serology. Conclusions: Between July and September 2020, the prevalence of anti-SARS-CoV-2 antigen was high in Shiraz. The prevalence of SARS-CoV-2 IgG/IgM antibodies in the high-risk group and their family as low risk was shown to increase viral infection due to close contact with COVID 19 patients than in the general population. Several factors were found to be related to the prevalence of anti-SARS-CoV-2 antigen that needs to be considered by policymakers to determine what to do about the SARS-CoV-2 pandemic.

Antibody Seroprevalence, Infection and Surveillance for SARS-CoV-2 in Residents and Staff of New Jersey Long-Term Care Facilities

Early in the pandemic, New Jersey (NJ) long-term care facilities (LTCFs) witnessed severe COVID-19 illness. With limited surveillance to characterize the scope of infection, we estimated the prevalence of antibody to the SARS-CoV-2 nucleocapsid protein among residents and staff, to describe the epidemiology, and to measure antibody distribution by prior PCR/antigen status and symptomatology. 10 NJ LTCFs of 20 solicited with diverse geography and bed-capacities were visited between October 2020 and March 2021. A single serum was tested for total N-antibody (ELISA) by the state laboratory. Residents' demographics and clinical history were transcribed from the patient record. For staff, this information was solicited directly from employees, supplemented by prior PCR/antigen results from facilities. 62% of 332 residents and 46% of 661 staff tested N-antibody positive. In a multivariable logistic regression in residents, odds ratios for older age and admission prior before March 1, 2020 were significant. Among the staff, odds ratios for older age, ethnic-racial group, nursing-related job, and COVID-19 symptoms were significantly associated with N-antibody positivity. In a sub-analysis in five better record-keeping LTCFs, 90% of residents and 85% of staff with positive PCR/antigen results were seropositive for N-antibody, yet 25% of residents and 22% of staff were N-antibody positive but PCR/antigen and symptoms negative. The high rate of clinically unsuspected infections likely contributed to the spread. These findings argue for robust surveillance, regular screening of asymptomatic individuals, and vaccinating both residents and staff to abate the pandemic. The data also provide guidance to prevent future outbreaks.

Short-Term Drop in Antibody Titer after the Third Dose of SARS-CoV-2 BNT162b2 Vaccine in Adults

Little is known about the longevity of antibodies after a third dose of the mRNA-based SARS-CoV-2 vaccine BNT162b2 (BioNTech/Pfizer, Mainz, Germany). Therefore, serum antibody levels were evaluated after a third dose of BNT162b2 in healthy adult healthcare workers in Germany. These antibody levels dropped significantly within a short period of 11 weeks from 4155.59 ± 2373.65 BAU/mL to 2389.10 ± 1433.90 BAU/mL, p-value < 0.001 but remained higher than after the second dose (611.92 ± 450.31 BAU/mL). To evaluate the quality of the humoral immune response, we additionally measured neutralizing antibodies, which also showed a small but significant decrease within this short period. These data underline the positive effect of a third dose of BNT162b2 concerning antibody re-induction but also shows a drop of Anti-SARS-CoV-2-IgG within a short span of time.

Cumulative incidence of SARS-CoV-2 infection and associated risk factors among frontline health care workers in Paris: the SEROCOV cohort study

With the COVID-19 pandemic, documenting whether health care workers (HCWs) are at increased risk of SARS-CoV-2 contamination and identifying risk factors is of major concern. In this multicenter prospective cohort study, HCWs from frontline departments were included in March and April 2020 and followed for 3 months. SARS-CoV-2 serology was performed at month 0 (M0), M1, and M3 and RT-PCR in case of symptoms. The primary outcome was laboratory-confirmed SARS-CoV-2 infection at M3. Risk factors of laboratory-confirmed SARS-CoV-2 infection at M3 were identified by multivariate logistic regression. Among 1062 HCWs (median [interquartile range] age, 33 [28–42] years; 758 [71.4%] women; 321 [30.2%] physicians), the cumulative incidence of SARS-CoV-2 infection at M3 was 14.6% (95% confidence interval [CI] [12.5; 16.9]). Risk factors were the working department specialty, with increased risk for intensive care units (odds ratio 1.80, 95% CI [0.38; 8.58]), emergency departments (3.91 [0.83; 18.43]) and infectious diseases departments (4.22 [0.92; 18.28]); current smoking was associated with reduced risk (0.36 [0.21; 0.63]). Age, sex, professional category, number of years of experience in the job or department, and public transportation use were not significantly associated with laboratory-confirmed SARS-CoV-2 infection at M3. The rate of SARS-CoV-2 infection in frontline HCWs was 14.6% at the end of the first COVID-19 wave in Paris and occurred mainly early. The study argues for an origin of professional in addition to private life contamination and therefore including HCWs in the first-line vaccination target population. It also highlights that smokers were at lower risk.

Trial registration The study has been registered on ClinicalTrials.gov: NCT04304690 first registered on 11/03/2020.

SARS-CoV-2 seroprevalence among healthcare personnel at a large health system in Atlanta

Background

Estimates of the prevalence of SARS-CoV-2 antibodies and factors associated with infection among healthcare personnel (HCP) vary widely. We conducted a serosurvey of HCP at a large public healthcare system in the Atlanta area.

Materials and methods

All employees of Grady Health System were invited to participate in mid-2020; a volunteer sample of those completing testing was included. Asymptomatic HCP were offered testing for IgG antibody and for SARS-CoV-2 RNA using polymerase chain reaction (PCR). Symptomatic HCP were offered PCR testing. Antibody index values for IgG and cycle threshold values for PCR were evaluated for those with a positive result. An online survey was distributed at the time of testing.

Results

624 of 1677 distributed surveys (37.2%) were completed by 608 unique HCP. The majority were female (76.4%) and provided clinical care (70.9%). The most common occupations were clinician (24.8%) and nurse (23.5%). 37 of 608 (6.1%) HCP had detectable IgG. Exposure to a confirmed case of COVID-19 outside of the hospital was associated with detectable IgG (12.8% vs 4.4%, p = 0.02), but exposure to a patient with COVID-19 was not.

Conclusions

Among HCP in a large healthcare system, 6.1% had detectable SARS-CoV-2 IgG. Seropositivity was associated with exposures outside of the healthcare setting.

COVID-19 Seroprevalence in Emergency Department Healthcare Professionals Study (COV-ED): A Cross-sectional study

Introduction

ED health care professionals are at the frontline of evaluation and management of patients with acute, and often undifferentiated, illness. During the initial phase of the SARS-CoV-2 outbreak, there were concerns that ED health care professionals may have been at increased risk of exposure to SARS-CoV-2 due to difficulty in early identification of patients. This study assessed the seroprevalence of SARS-CoV-2 antibodies among ED health care professionals without confirmed history of COVID-19 infection at a quaternary academic medical center.

Methods

This study used a cross-sectional design. An ED health care professional was deemed eligible if they had worked at least 4 shifts in the adult emergency department from April 1, 2020, through May 31, 2020, were asymptomatic on the day of blood draw, and were not known to have had prior documented COVID-19 infection. The study period was December 17, 2020, to January 27, 2021. Eligible participants completed a questionnaire and had a blood sample drawn. Samples were run on the Roche Cobas Elecsys Anti-SARS-CoV-2 antibody assay.

Results

Of 103 health care professionals (16 attending physicians, 4 emergency residents, 16 advanced practice professionals, and 67 full-time emergency nurses), only 3 (2.9%; exact 95% CI, 0.6%-8.3%) were seropositive for SARS-CoV-2 antibodies.

Discussion

At this quaternary academic medical center, among those who volunteered to take an antibody test, there was a low seroprevalence of SARS-CoV-2 antibodies among ED clinicians who were asymptomatic at the time of blood draw and not known to have had prior COVID-19 infection.

A Prospective, Longitudinal Evaluation of SARS-CoV-2 COVID-19 Exposure, Use of Protective Equipment and Social Distancing in a Group of Community Physicians

Introduction: Healthcare workers experience a significant risk of exposure to and infection from SARS-CoV-2, COVID-19. Nonetheless, little research has focused on physicians’ use of personal protective equipment (PPE), their concerns about becoming infected and their social distancing maneuvers. Methods: All staff physicians at Advocate Lutheran General Hospital were invited to participate. Their COVID-19 IgG antibody level was measured and an online questionnaire was completed. The questionnaire assessed the risk of COVID-19 exposure, PPE usage, concern for contracting COVID-19, the performance of high-risk procedures, work in high-risk settings, and social distancing practices. Testing was performed in September (T0), and December 2020 (T1) at the height of the global pandemic. Results: A total of 481 (26.7%) of 1800 AGLH physicians were enrolled at T0 and 458 (95% of the original group) at T1. A total of 21 (4.3%) and 39 (8.5%) participants had antibodies at T0 and T1. A total of 63 (13.8%) worked in high-risk settings and 111 (24.2%) performed high-risk procedures. Participants working in high-risk settings had increased exposure to COVID-19 infected patients (OR = 4.464 (CI = 2.522–8.459, p < 0.001). Participants were highly adherent to the use of PPE and social distancing practices including mask-wearing in public (86%, 82.1%), avoiding crowds (85.1%, 85.6%), six feet distancing (83.8%, 83.4%), and avoiding public transportation (78%, 83.8%). A total of 251 (55.4%) participants expressed moderate to extreme concern about becoming infected with COVID-19. Conclusions and Relevance: Among a group of community physicians, consistent PPE use and social distancing practices were common. These practices were associated with a low level of initial acquisition of COVID-19 infections and a relatively low longitudinal risk of infection.

Immunoglobulin-G Antibodies against Severe Acute Respiratory Syndrome - Coronavirus-2 among Health-Care Workers: A Serosurveillance Study from India

Background:

Seropositivity among health-care workers (HCWs) may help in better understanding of the immune response after COVID-19 infection.

Objectives:

To estimate seropositivity among HCWs and to compare available variables with seropositivity to understand the factors affecting seropositivity.

Materials and Methods:

A serosurveillance among HCWs was carried out using population proportion sampling during the second half of October 2020 in the city of Ahmedabad using the Covid-Kavach (immunoglobulin G [IgG] ELISA Antibody testing kit). Simple proportions and appropriate statistical tests were used as needed.

Results:

As on October' 2020, HCWs in Ahmedabad demonstrated a seropositivity of 20.84% (95% confidence interval [CI] 19.00–22.81%). Seropositivity among HCWs was lower than that of the general population (24.20%) which was estimated as part of the same study. Female HCWs had higher seropositivity 22.14% (95% CI 19.74–24.74%) as compared to 18.82% (95% CI 16.06–21.93%) among male HCWs and the difference was statistically not significant (Z = 1.66, P = 0.097). Age groups with increasing age show increasing trend in the seropositivity among HCWs.

Conclusion:

As on October 2020, with 20.84% seropositivity among HCWs in Ahmedabad, one in every five HCW already demonstrate IgG antibodies against severe acute respiratory syndrome– coronavirus-2. Further scientific studies on seropositivity and the factors affecting the seropositivity may be carried out to uncover more details of immune reaction after COVID-19 infection.

Prevalence of SARS-CoV-2 Infection in a Sample of Health Workers in Two Health Departments of the Valencian Community in Spain

Health care personnel constitutes the most vulnerable group of professionals, as they are employed in a work context with higher exposure to SARS-CoV-2 infection. This study aims to estimate the prevalence of SARS-CoV-2 infection in health personnel (n = 2858) of two health departments in the Valencian community between March 2020 and April 2021, as well as the sociodemographic and work variables predicting higher infection prevalence in this group. A cross-sectional descriptive study was performed on health workers from the health departments of Torrevieja and Elche-Crevillente of the Valencian Community (Spain). After obtaining the samples, the cases were identified through an active infection diagnostic test (AIDT). The analyzed variables were: sex, age (18-34/35-49/>50 years), professional category, health care, risk service, and AIDT. A total of 2858 staff members were studied. Of them, 55.4% (1582) underwent an AIDT, with 9.7% (277) of positive cases. Infection predominated in the age group of 18 to 34 years, 12.6% (OR = 1.98, 95% CI [1.26, 3.11]); nurses, 12.1% (OR = 1.5, 95% CI [1.00, 2.23]); and at-risk services, 11.4% (OR = 1.3, 95% CI [1.06, 1.81]). A very low positivity rate was identified in the health personnel linked to the health departments analyzed during the 14 months of the study period. Based on our results, prevention strategies could focus more intensively on the most at-risk groups, specifically young nurses who work in at-risk services, mainly in emergency and internal medicine.

SARS-CoV-2-antibody response in health care workers after vaccination or natural infection in a longitudinal observational study

Background

Following a year of development, several vaccines have been approved to contain the global COVID-19 pandemic. Real world comparative data on immune response following vaccination or natural infection are rare.

Methods

We conducted a longitudinal observational study in employees at a secondary care hospital affected by the COVID-19 pandemic. Comparisons were made about the presence of anti-SARS-CoV-2 immunglobulin G (IgG) antibody ratio after natural infection, or vaccination with one or two doses of BioNTech/Pfizer (BNT162b2), or one dose of AstraZenca (Vaxzevria) vaccine.

Results

We found a 100% humoral response rate in participants after 2 doses of BNT162b2 vaccine. The antibody ratio in participants with one dose BNT162b2 and Vaxzevria did not differ significantly to those with previous PCR-confirmed infection, whereas this was significantly lower in comparison to two doses of BioNTech/Pfizer. We could not identify a correlation with previous comorbidities, obesity or age within this study. Smoking showed a negative effect on the antibody response (p = 0.006)

Conclusion

Our data provide an overview about humoral immune response after natural SARS-CoV-2 infection or following vaccination, and supports the usage of booster vaccinations, especially in patients after a natural SARS-CoV-2 infection.

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.

Longitudinal Follow Up of Immune Responses to SARS-CoV-2 in Health Care Workers in Sweden With Several Different Commercial IgG-Assays, Measurement of Neutralizing Antibodies and CD4+ T-Cell Responses

Background

The risk of SARS-CoV-2 infection among health care workers (HCWs) is a concern, but studies that conclusively determine whether HCWs are over-represented remain limited. Furthermore, methods used to confirm past infection vary and the immunological response after mild COVID-19 is still not well defined.

Method

314 HCWs were recruited from a Swedish Infectious Diseases clinic caring for COVID-19 patients. IgG antibodies were measured using two commercial assays (Abbot Architect nucleocapsid (N)-assay and YHLO iFlash-1800 N and spike (S)-assays) at five time-points, from March 2020 to January 2021, covering two pandemic waves. Seroprevalence was assessed in matched blood donors at three time-points. More extensive analyses were performed in 190 HCWs in September/October 2020, including two additional IgG-assays (DiaSorin LiaisonXL S1/S2 and Abbot Architect receptor-binding domain (RBD)-assays), neutralizing antibodies (NAbs), and CD4+ T-cell reactivity using an in-house developed in vitro whole-blood assay based on flow cytometric detection of activated cells after stimulation with Spike S1-subunit or Spike, Membrane and Nucleocapsid (SMN) overlapping peptide pools.

Findings

Seroprevalence was higher among HCWs compared to sex and age-matched blood donors at all time-points. Seropositivity increased from 6.4% to 16.3% among HCWs between May 2020 and January 2021, compared to 3.6% to 11.9% among blood donors. We found significant correlations and high levels of agreement between NAbs and all four commercial IgG-assays. At 200-300 days post PCR-verified infection, there was a wide variation in sensitivity between the commercial IgG-assays, ranging from <30% in the N-assay to >90% in the RBD-assay. There was only moderate agreement between NAbs and CD4+ T-cell reactivity to S1 or SMN. Pre-existing CD4+ T-cell reactivity was present in similar proportions among HCW who subsequently became infected and those that did not.

Conclusions

HCWs in COVID-19 patient care in Sweden have been infected with SARS-CoV-2 at a higher rate compared to blood donors. We demonstrate substantial variation between different IgG-assays and propose that multiple serological targets should be used to verify past infection. Our data suggest that CD4+ T-cell reactivity is not a suitable measure of past infection and does not reliably indicate protection from infection in naive individuals.

Prevalence of anti-SARS-CoV-2 IgG antibodies in a group of patients, a control group, and healthcare workers of Thrace area in Greece, by the use of two distinct methods

Introduction

The aim of this study was to assess the clinical performance of different automated immunoassays available in Europe to detect anti-SARS-CoV-2 antibodies; an ELISA assay and a CLIA. The second goal was to estimate the seroprevalence of SARS-CoV-2 antibodies among healthcare workers in Evros area during the first pandemic wave of COVID-19.

Methods

The study included serum samples from 101 patients with confirmed COVID-19 by RT-PCR and 208 negative patients. Furthermore, it included 1036 healthcare workers (HWs) of the Evros Region, Northern Greece. The measurement of anti-SARS-CoV-2 antibodies was performed using the Abbott SARS-CoV-2 IgG and anti-SARS-CoV-2 ELISA IgG assay (Epitope Diagnostics, USA).

Results

Of 101 confirmed COVID-19 patients, 82 were hospitalized and 19 were outpatients. Hospitalized patients had higher IgG levels in comparison to outpatients (6.46±2.2 vs. 3.52±1.52, p<0.001). Of 208 non-COVID-19 patients only 1 was positive in both ELISA and CLIA assay. SARS-CoV-2-IgG antibodies were detected in 6 HWs out of 1036 (0.58%) with mean S/CO-value of anti-SARS-CoV-2 IgG 3.12±1.3 (confidence interval 0.95), which was lower than in COVID-19 patients (3.12 vs. 5.9; p=0.016). The clinical evaluation of two immunoassays showed remarkably high true positivity rates in the confirmed COVID-19 patients. Sensitivities obtained with CLIA and ELISA methods were 99.02% vs. 97.09% and specificities 99.52% vs 99.05% respectively.

Conclusions

We found an acceptable accordance between CLIA and ELISA assays in the confirmed COVID-19 patients. In all subjects included in this study in the past medical history, the information that was obtained included details about the presence of autoimmune diseases.

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

AIM

We aimed to assess prevalence of IgG antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and factors associated with seropositivity in a large cohort of healthcare workers (HCWs).

METHODS

From 11 May until 11 June 2020, 3981 HCWs at a large Swedish emergency care hospital provided serum samples and questionnaire data. Presence of IgG antibodies to SARS-CoV-2 was measured as an indicator of SARS-CoV-2 exposure.

RESULTS

The total seroprevalence was 18% and increased during the study period. Among the seropositive HCWs, 11% had been entirely asymptomatic. Participants who worked with COVID-19 patients had higher odds for seropositivity: adjusted odds ratio 1.96 (95% confidence intervals 1.59-2.42). HCWs from three of the departments managing COVID-19 patients had significantly higher seroprevalences, whereas the prevalence among HCWs from the intensive care unit (also managing COVID-19 patients) was significantly lower.

CONCLUSIONS

HCWs in contact with SARS-CoV-2 infected patients had a variable, but on average higher, likelihood for SARS-CoV-2 infections.

A cross-sectional study of SARS-CoV-2 seroprevalence among asymptomatic healthcare workers in a tertiary healthcare centre: Assessing the impact of PPE guidelines

Purpose

The present study estimates the seroprevalence of SARS-COV-2 among asymptomatic HCWs and assess the impact of various categories of PPE.

Methods

A cross-sectional study of asymptomatic HCW using different levels of PPE as per their risk profile was undertaken between 18th and 24th September 2020. Participant demographics and other relevant details including the levels of PPE used were recorded using a customized questionnaire. IgG antibodies against SARS-COV-2 were detected by chemiluminescence method & used as a surrogate marker for incomplete protection.

Results

Out of 1033 HCWs tested, overall SARS-COV-2 sero-prevalence was 25.8%. Univariate and multivariate analysis both demonstrated that ancillary workers including security staff (OR 5.589, P ​< ​0.001) and sanitary workers (OR 3.946, P ​< ​0.001) were at significantly higher risk of seropositivity irrespective of the PPE used as per guidelines, whereas doctors were at significantly lower risk of seropositivity (OR 0.307, P ​= ​0.005). Staff working in office areas was associated with reduced risk of seropositivity (OR 0.21, P ​= ​0.045).

Conclusions

We document high seroprevalence of SARS-COV-2 antibodies in asymptomatic HCWs. Doctors who are at the highest risk had the lowest seropositivity and seroprevalence among office staff having a risk level comparable to the general community was lower than that reported in general population, supporting the efficacy of PPE practices as per guidelines in these groups. In contrast, much higher rates of seropositivity were seen among ancillary workers despite the availability of adequate PPE. Active screening, proper PPE use as per guidelines, and regular infection control trainings including Covid appropriate behaviour are therefore essential to contain COVID-19 spread among HCW & preventing them to transfer infection to the patients.

Half-Year Longitudinal Seroprevalence of SARS-CoV-2-Antibodies and Rule Compliance in German Hospital Employees

COVID-19, which is caused by SARS-CoV-2, is an occupational health risk, especially for healthcare employees due to their higher exposure and consequently higher risk of symptomatic and asymptomatic infections. This study was designed to determine the longitudinal seroprevalence of specific immunoglobulin-G (IgG) antibodies in employees in a hospital setting. All employees in a secondary care hospital, including healthcare and non-healthcare workers, were invited to participate in this single-center study. After an initial screening, a 6-month follow-up was carried out, which included serological examination for SARS-CoV-2 IgG antibodies and a questionnaire for self-reported symptoms, self-perception, and thoughts about local and national hygiene and pandemic plans. The seroprevalence of SARS-CoV-2 IgG antibodies was 0.74% among 406 hospital employees (0.75% in healthcare workers, 0.72% in non-healthcare workers), initially recruited in April 2020, in their follow-up blood specimens in October 2020. In this study, 30.54% of the participants reported using the official German coronavirus mobile application and the majority were content with the local and national rules in relation to coronavirus-related restrictions. At the 6-month follow-up, the 0.74% seroprevalence was below the reported seroprevalence of 1.35% in the general German population. The prevalence in healthcare workers in direct patient care compared with that in workers without direct patient contact did not differ significantly. Further follow-up to monitor the seroprevalence in the high-risk healthcare sector during the ongoing global pandemic is essential.

Systematic review of productivity loss among healthcare workers due to Covid-19

Objective

To assess existing evidence on the effects of COVID‐19 on healthcare workers (HCWs) using the health‐related productivity loss approach.

Methods

A systematic search of online databases including PubMed, Scopus, Ovid, Web of Science, and EMBASE was conducted up to 25 August 2020. Following two screening stages, studies related to the effects of COVID‐19 on healthcare workers were included in the study.

Results

82 studies were included in the analysis. The COVID‐19 related death rate among HCWs ranged from 0.00‐0.7%, while the positive test incidence varied between 0.00 and 24.4%. 39 evidences assessed psychological disorders. A wide range of psychological disorders observed among HCWs: 5.2 to 71.2% in anxiety, 1.00 to 88.3% in stress, 8.27 to 61.67% in insomnia, and 4.5 to 50.4% in depression.

Conclusions

The early evidence suggests that healthcare workers are one of the most vulnerable groups when it comes to positive COVID‐19 infection, mortality, and mental illness.

SARS-CoV-2 antibodies in Ontario health care workers during and after the first wave of the pandemic: a cohort study

BACKGROUND

Health care workers have a critical role in the pandemic response to COVID-19 and may be at increased risk of infection. The objective of this study was to assess the seroprevalence of SARS-CoV-2 immunoglobulin G (IgG) antibodies among health care workers during and after the first wave of the pandemic.

METHODS

We conducted a prospective multicentre cohort study involving health care workers in Ontario, Canada, to detect IgG antibodies against SARS-CoV-2. Blood samples and self-reported questionnaires were obtained at enrolment, at 6 weeks and at 12 weeks. A community hospital, tertiary care pediatric hospital and a combined adult-pediatric academic health centre enrolled participants from Apr. 1 to Nov. 13, 2020. Predictors of seropositivity were evaluated using a multivariable logistic regression, adjusted for clustering by hospital site.

RESULTS

Among the 1062 health care workers participating, the median age was 40 years, and 834 (78.5%) were female. Overall, 57 (5.4%) were seropositive at any time point (2.5% when participants with prior infection confirmed by polymerase chain reaction testing were excluded). Seroprevalence was higher among those who had a known unprotected exposure to a patient with COVID-19 (p < 0.001) and those who had been contacted by public health because of a nonhospital exposure (p = 0.003). Providing direct care to patients with COVID-19 or working on a unit with a COVID-19 outbreak was not associated with higher seroprevalence. In multivariable logistic regression, presence of symptomatic contacts in the household was the strongest predictor of seropositivity (adjusted odds ratio 7.15, 95% confidence interval 5.42-9.41).

INTERPRETATION

Health care workers exposed to household risk factors were more likely to be seropositive than those not exposed, highlighting the need to emphasize the importance of public health measures both inside and outside of the hospital.

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.

Sero-prevalence of anti-SARS-CoV-2 antibodies among healthcare workers: A multicenter study from Egypt

Background

Healthcare workers (HCWs) are at a high risk for disease exposure. Given the limited availability of nucleic acid testing by PCR in low resource settings, serological assays can provide useful data on the proportion of HCWs who have recently or previously been infected. Therefore, in this study, we conducted an immunologic study to determine the seroprevalence of anti-SARS-CoV-2 antibodies in two university hospitals in Egypt.

Methods

in this cross sectional study, HCWs who were working in SARS-CoV-2 Isolation Hospitals were interviewed. Estimating specific antibodies (IgM and IgG) against SARS-CoV-2 was carried out using an enzyme-linked immunosorbent assay targeting the Spike antigen of SARS-CoV-2 virus.

Results

Out of 111, 82 (74%) HCWs accepted to participate with a mean age of 31.5 ± 8.5 years. Anti-SARS-COV2 antibodies were detected in 38/82 (46.3%) of cases with a mean age of 31 years and female HCWs constituted 57.6% of cases. The highest rate of seropositivity was from the nurses (60.5%), and physicians (31.6%) with only (7.9%) technicians. Only 28/82 (34.1%) HCWs reported previous history of COVID19. We reported a statistically significant difference in the timing of exposure (p = 0.010) and the frequency of contact with COVID-19 cases (p = 0.040) between previously infected and on-infected HCWs. Longer time of recovery was reported from IgG positive HCWs (p = 0.036).

Conclusion

The high frequency of seropositive HCWs in investigated hospitals is alarming, especially among asymptomatic personnel. Confirmation of diseased HCWs (among seropositive ones) are warranted.

Seroprevalence of SARS-CoV-2 antibodies among homeless people living rough, in shelters and squats: A large population-based study in France

Background

Overcrowded housing, as well as inadequate sanitary conditions, contribute to making homeless people particularly vulnerable to the SARS-CoV-2 infection. We aimed to assess the seroprevalence of the SARS-CoV-2 infection among people experiencing homelessness on a large city-wide scale in Marseille, France, taking into account different types of accommodation.

Methods

A consortium of outreach teams in 48 different locations including streets, slums, squats, emergency or transitional shelters and drop-in centres participated in the inclusion process. All participants consented to have a validated rapid antibody assay for immunoglobulins M (IgM) and G (IgG) and to answer a questionnaire on medical health conditions, comorbidities, and previous COVID-19 symptoms. Information on their housing conditions since the COVID-19 crisis was also collected from the participants.

Results

From June 01 to August 05, 2020, 1,156 homeless participants were enrolled in the study and tested. The overall seroprevalence of SARS-CoV-2 IgG/IgM antibodies was 5.6% (95%CI 2.3–7.0), ranging from 2.2% in people living on the streets to 8.1% in people living in emergency shelters (P = 0.009). Around one third of the seropositive participants reported COVID-19 symptoms. Compared to the general population in Marseille (3.6%), the homeless population living in the same urban area experienced a significantly increased risk of SARS-CoV-2 infection (|z| = 3.65 > 1.96).

Conclusion

These findings highlight the need for regular screening among the homeless to prevent clustering in overcrowded or inadequate accommodations. It is also necessary to provide essential resources to keep homeless people healthy, the vast majority of whom have cumulative risk factors for SARS-CoV-2 infection.

Rapid and Laboratory SARS-CoV-2 Antibody Testing in High-Risk Hospital Associated Cohorts of Unknown COVID-19 Exposure, a Validation and Epidemiological Study After the First Wave of the Pandemic

Objective: We aimed to use SARS-CoV-2 antibody tests to assess the asymptomatic seroprevalence of individuals in high-risk hospital cohorts who's previous COVID-19 exposure is unknown; staff, and patients requiring haemodialysis or chemotherapy after the first wave.

Methods: In a single Center, study participants had five SARS-CoV-2 antibody tests done simultaneously; one rapid diagnostic test (RDT) (Superbio Colloidal Gold IgM/IgG), and four laboratory tests (Roche Elecsys® Anti-SARS-CoV-2 IgG [RE], Abbott Architect i2000SR IgG [AAr], Abbott Alinity IgG [AAl], and Abbott Architect IgM CMIA). To determine seroprevalence, only positive test results on laboratory assay were considered true positives.

Results: There were 157 participants, of whom 103 (65.6%) were female with a median age of 50 years (range 19–90). The IgG component of the RDT showed a high number of false positives (n = 18), was inferior to the laboratory assays (p < 0.001 RDT vs. AAl/AAr, p < 0.001 RDT vs. RE), and had reduced specificity (85.5% vs. AAl/AAr, 87.2% vs. RE). Sero-concordance was 97.5% between IgG laboratory assays (RE vs. AAl/AAr). Specificity of the IgM component of the RDT compared to Abbott IgM CMIA was 95.4%. Ten participants had positivity in at least one laboratory assay, seven (9.9%) of which were seen in HCWs. Two (4.1%) hematology/oncology (H/O) patients and a single (2.7%) haemodialysis (HD) were asymptomatically seropositive. Asymptomatic seroprevalence of HCWs compared to patients was not significant (p = 0.105).

Conclusion: HCWs (9.9%) had higher, although non-significant asymptomatic seroprevalence of SARS-CoV-2 antibodies compared to high-risk patients (H/O 4.1%, HD 2.7%). An IgM/IgG rapid diagnostic test was inferior to laboratory assays. Sero-concordance of 97.5% was found between IgG laboratory assays, RE vs. AAl/AAr.

Serological assessment of SARS-CoV-2 infection during the first wave of the pandemic in Louisville Kentucky

Serological assays intended for diagnosis, sero-epidemiologic assessment, and measurement of protective antibody titers upon infection or vaccination are essential for managing the SARS-CoV-2 pandemic. Serological assays measuring the antibody responses against SARS-CoV-2 antigens are readily available. However, some lack appropriate characteristics to accurately measure SARS-CoV-2 antibodies titers and neutralization. We developed an Enzyme-linked Immunosorbent Assay (ELISA) methods for measuring IgG, IgA, and IgM responses to SARS-CoV-2, Spike (S), receptor binding domain (RBD), and nucleocapsid (N) proteins. Performance characteristics of sensitivity and specificity have been defined. ELISA results show positive correlation with microneutralization and Plaque Reduction Neutralization assays with infectious SARS-CoV-2. Our ELISA was used to screen healthcare workers in Louisville, KY during the first wave of the local pandemic in the months of May and July 2020. We found a seropositive rate of approximately 1.4% and 2.3%, respectively. Our analyses demonstrate a broad immune response among individuals and suggest some non-RBD specific S IgG and IgA antibodies neutralize SARS-CoV-2.

Health Care Workers' Attitudes Toward Patients With COVID-19

BACKGROUND

Early in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, before the routine availability and/or use of personal protective equipment, health care workers were understandably concerned. Our aim was to explore health care workers' attitudes toward patients infected with SARS-CoV-2 at the time of the nation's first surge in 2 highly affected hospitals in New York.

METHODS

We performed a cross-sectional, self-administered survey study of health care workers. The survey consisted of 17 multiple-choice questions including demographic information, ethics, and willingness to care for patients with SARS-CoV-2 infection. Subgroup analyses were performed using the Fisher exact test.

RESULTS

Of 340 health care workers approached, 338 (99.4%) consented to the survey; 163 (48.7%) were registered nurses and 160 (48.3%) lived with children. While 326 (97.3%) workers were concerned about putting their family/coworkers at risk of infection after caring for a patient with SARS-CoV-2, only 30 (8.9%) were unwilling to treat a patient with SARS-CoV-2 infection. Registered nurses were more likely than other health care workers to think it was ethical to refuse care for SARS-CoV-2-infected patients, worried more often about contracting infection, and felt that SARS-CoV-2 added to their stress level (P = .009, P = .018, P < .001, respectively). A similar contrast was seen when comparing workers who live with children with those who did not.

CONCLUSIONS

Levels of stress and concern were extremely high. In spite of that, the overwhelming majority of workers were willing to treat patients with SARS-CoV-2 infection. Registered nurses and health care workers who live with children were more likely to think it is ethical to refuse care for SARS-CoV-2-infected patients.

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.

Ocrelizumab for the Treatment of Multiple Sclerosis: Safety, Efficacy, and Pharmacology

The success of selective B-cells depleting therapies, as the anti-CD20 antibodies, in patients with multiple sclerosis (MS) has confirmed that B-cells are critical in the immune pathogenesis of the disease. Ocrelizumab, a humanized monoclonal antibody that selectively targets CD20+ B-cells, profoundly suppresses acute inflammatory disease activity, representing a highly effective therapy for relapsing-remitting multiple sclerosis (RRMS). It is also the first proven therapy able to slow disability progression in primary progressive multiple sclerosis (PPMS), particularly in patients with signs of acute radiological activity before being enrolled. Effectiveness has widely been demonstrated in randomized clinical trials (RCTs), and recently confirmed in open-label extension trials. Here, we review the role of B-cells in MS, the mechanism of action of ocrelizumab, its pharmacokinetics and pharmacodynamics, and the clinical data supporting its use, as well as safety data. We focus on issues related to the maintenance of immunocompetence, essential to ensure an immune response to either a primary infection or a vaccination. Lastly, we discuss about the possible role of ocrelizumab as an exit strategy from natalizumab-treated patients at risk of developing multifocal progressive leukoencephalopathy. In view of using ocrelizumab chronically, collecting long-term safety data and finding strategies to minimize adverse events will be extremely relevant.

Seropositivity of severe acute respiratory syndrome coronavirus 2 infection among healthcare workers of the Armed Forces medical services, India: A multicentric study

Background

Serosurveys provide the prevalence of infection and over time will reveal the trends. The present study was conducted to estimate the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers (HCWs) and to analyse various characteristics (risk factors) associated with SARS CoV-2 infection.

Methods

Eight government designated Corona virus disease -19 (COVID-19) hospitals were selected based on the hospital admission of patients with COVID-19 and the local epidemiological situation in the region. Multistage population proportion to size sampling was performed for the selection of HCWs. Serosurvey was conducted using the enzyme-linked immunosorbent assay-based IgG antibody test (COVID KAVACH). Bivariate and multiple logistic regression was performed to find out the factor/factors associated with the positive antibody test.

Results

Out of 3255 HCWs that participated in the study, data of 3253 were analysed. The seroprevalence was 19.7% (95% confidence interval: 18.5-21.3%). Factors associated were location, category of HCWs, male sex, previously tested positive by the molecular test, training on infection prevention and control, personal protective measures, handwashing technique, close contact with a patient confirmed with COVID-19, use of personal protective equipment and symptoms in the last 30 days. However, in multiple logistic regression, only location, category, previously tested positive by the molecular test and symptoms in the last 30 days were statistically significant.

Conclusion

HCWs are vulnerable to SARS-CoV-2 infection. One in five HCWs had detectable antibodies. The presence of antibodies among HCWs may help in their placement and triage. HCWs may be advised to report early in case of any symptoms of COVID-19. Preventive measures may be targeted based on the location, with particular emphasis on ancillary workers and nurses.

SARS-CoV-2 seroprevalence in healthcare workers of a Swiss tertiary care centre at the end of the first wave: a cross-sectional study

OBJECTIVE

To assess the SARS-CoV-2 transmission in healthcare workers (HCWs) using seroprevalence as a surrogate marker of infection in our tertiary care centre according to exposure.

DESIGN

Seroprevalence cross-sectional study.

SETTING

Single centre at the end of the first COVID-19 wave in Lausanne, Switzerland.

PARTICIPANTS

1874 of 4074 responders randomly selected (46% response rate), stratified by work category among the 13 474 (13.9%) HCWs.

MAIN OUTCOME MEASURES

Evaluation of SARS-CoV-2 serostatus paired with a questionnaire of SARS-CoV-2 acquisition risk factors internal and external to the workplace.

RESULTS

The overall SARS-CoV-2 seroprevalence rate among HCWs was 10.0% (95% CI 8.7% to 11.5%). HCWs with daily patient contact did not experience increased rates of seropositivity relative to those without (10.3% vs 9.6%, respectively, p=0.64). HCWs with direct contact with patients with COVID-19 or working in COVID-19 units did not experience increased seropositivity rates relative to their counterparts (10.4% vs 9.8%, p=0.69 and 10.6% vs 9.9%, p=0.69, respectively). However, specific locations of contact with patients irrespective of COVID-19 status-in patient rooms or reception areas-did correlate with increased rates of seropositivity (11.9% vs 7.5%, p=0.019 and 14.3% vs 9.2%, p=0.025, respectively). In contrast, HCWs with a suspected or proven SARS-CoV-2-infected household contact had significantly higher seropositivity rates than those without such contacts (19.0% vs 8.7%, p<0.001 and 42.1% vs 9.4%, p<0.001, respectively). Finally, consistent use of a mask on public transportation correlated with decreased seroprevalence (5.3% for mask users vs 11.2% for intermittent or no mask use, p=0.030).

CONCLUSIONS

The overall seroprevalence was 10% without significant differences in seroprevalence between HCWs exposed to patients with COVID-19 and HCWs not exposed. This suggests that, once fully in place, protective measures limited SARS-CoV-2 occupational acquisition within the hospital environment. SARS-CoV-2 seroconversion among HCWs was associated primarily with community risk factors, particularly household transmission.

Sero-Prevalence of SARS-CoV-2 Antibodies in High-Risk Populations in Vietnam

As a response to the coronavirus disease 2019 (COVID-19) pandemic, Vietnam enforced strict quarantine, contact tracing and physical distancing policies resulting in one of the lowest numbers of individuals infected with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) globally. This study aimed to determine the prevalence of SARS-CoV-2 antibody positivity among high-risk populations in Vietnam. A prevalence survey was undertaken within four communities in Vietnam, where at least two COVID-19 cases had been confirmed. Participants were classified according to the location of exposure: household contacts, close contacts, community members, and healthcare workers (HCWs) responsible for treating COVID-19 cases. Participants completed a baseline questionnaire and SARS-CoV-2 IgG antibodies were quantified using a commercial assay. A total of 3049 community members and 149 health care workers consented to the study. Among 13 individuals who were seropositive (0.4%), five household contacts (5/27, 18.5%), one close contact (1/53, 1.9%), and seven community members (7/2954, 0.2%) had detectable SARS-CoV-2 antibodies. All HCWs were negative for SARS-CoV-2 antibodies. Participants were tested a median of 15.1 (interquartile range from 14.9 to 15.2) weeks after exposure. Our study found a low prevalence of SARS-CoV-2 antibodies in high-risk communities and healthcare workers in communities in Vietnam with known COVID-19 cases.

Seroprevalence study of SARS-CoV-2 antibodies in healthcare workers following the first wave of the COVID-19 pandemic in a tertiary-level hospital in the south of Ireland

OBJECTIVE

This study investigated seroprevalence of SARS-CoV-2-specific IgG antibodies, using the Abbott antinucleocapsid IgG chemiluminescent microparticle immunoassay (CMIA) assay, in five prespecified healthcare worker (HCW) subgroups following the first wave of the COVID-19 pandemic.

SETTING

An 800-bed tertiary-level teaching hospital in the south of Ireland.

PARTICIPANTS

Serum was collected for anti-SARS-CoV-2 nucleocapsid IgG using the Abbott ARCHITECT SARS-CoV-2 IgG CMIA qualitative assay, as per the manufacturer's specifications.The groups were as follows: (1) HCWs who had real-time PCR (RT-PCR) confirmed COVID-19 infection (>1-month postpositive RT-PCR); (2) HCWs identified as close contacts of persons with COVID-19 infection and who subsequently developed symptoms (virus not detected by RT-PCR on oropharyngeal/nasopharyngeal swab); (3) HCWs identified as close contacts of COVID-19 cases and who remained asymptomatic (not screened by RT-PCR); (4) HCWs not included in the aforementioned groups working in areas determined as high-risk clinical areas; and (5) HCWs not included in the aforementioned groups working in areas determined as low-risk clinical areas.

RESULTS

Six of 404 (1.49%) HCWs not previously diagnosed with SARS-CoV-2 infection (groups 2-5) were seropositive for SARS-CoV-2 at the time of recruitment into the study.Out of the 99 participants in group 1, 72 had detectable IgG to SARS-CoV-2 on laboratory testing (73%). Antibody positivity correlated with shorter length of time between RT-PCR positivity and antibody testing.Quantification cycle value on RT-PCR was not found to be correlated with antibody positivity.

CONCLUSIONS

Seroprevalence of SARS-CoV-2 antibodies in HCWs who had not previously tested RT-PCR positive for COVID-19 was low compared with similar studies.

SARS-CoV-2 Seroprevalence Among Healthcare Workers by Job Function and Work Location in a New York Inner-City Hospital

OBJECTIVE

To describe the seroprevalence and risk for SARS-CoV-2 among healthcare workers (HCWs) by job function and work location following the pandemic's first wave in New York City (NYC).

METHODS

A cross-sectional study conducted between May 18 and June 26, 2020, during which HCWs at a large inner-city teaching hospital in NYC received voluntary antibody testing. The main outcome was presence of SARS-CoV-2 antibodies indicating previous infection. Seroprevalence and adjusted odds ratios (aORs) for seropositivity by type and location of work were calculated using logistic regression analyses.

RESULTS

Of 2,749 HCWs tested, 831 tested positive, yielding a crude seroprevalence of 30.2% (95% CI, 29%-32%). Seroprevalence ranged from 11.1% for pharmacy staff to 44.0% for nonclinical HCWs comprised of patient transporters and housekeeping and security staff, with 37.5% for nurses and 20.9% for administrative staff. Compared to administrative staff, aORs (95% CIs) for seropositivity were 2.54 (1.64-3.94) for nurses; 2.51 (1.42-4.43) for nonclinical HCWs; between 1.70 and 1.83 for allied HCWs such as patient care technicians, social workers, registration clerks and therapists; and 0.80 (0.50-1.29) for physicians. Compared to office locations, aORs for the emergency department and inpatient units were 2.27 (1.53-3.37) and 1.48 (1.14-1.92), respectively.

CONCLUSION

One-third of hospital-based HCWs were seropositive for SARS-CoV-2 by the end of the first wave in NYC. Seroprevalence differed by job function and work location, with the highest estimated risk for nurses and the emergency department, respectively. These findings support current nationwide policy prioritizing HCWs for receipt of newly authorized COVID-19 vaccines.

Screening and Confirmatory Testing for SARS-CoV-2 Antibodies: Comparison of Health and Non-Health Workers in a Nationwide Healthcare Organization in Central Europe

Despite being located close to the European epicenter of the COVID-19 pandemic in Italy, Austria has managed to control the first wave. In Austria, the largest health insurance fund covers 7 million people and has 12,000 employees, including 3700 healthcare workers (HCW). For patient and staff safety, transmission control measures were implemented and mass testing of employees for SARS-CoV-2 antibodies was conducted. An IgG SARS-CoV-2 rapid test on fingerstick blood was used as a screening test (ST), followed by serologic studies with 3 different immunoassays and confirmatory testing by a neutralization test (NT). Among 7858 employees, 144 had a positive ST and 88 were confirmed by a NT (1.12%, CI: 0.9–1.38%). The positive predictive value (PPV) of the ST was 69.3% (CI: 60.5–77.2). Interestingly, 40% of the NT positive serum samples were tested negative in all 3 immunoassays. Of the total sample, 2242 HCW (28.5%) were identified. Unexpectedly, there was no difference in the prevalence of NT positives in HCW compared to non-HCW (23/2242 vs. 65/5301, p = 0.53). SARS-CoV-2 antibody prevalence was not increased among HCW. Although HCW are at potentially increased risk for SARS-CoV-2 infection, transmission control measures in healthcare facilities appear sufficient to limit transmission of infection.

The role of supporting services in driving SARS-CoV-2 transmission within healthcare settings: A multicenter seroprevalence study

Objective

To determine the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in healthcare workers (HCWs) based on risk of exposure to COVID-19 patients.

Method

This was a SARS-CoV-2 seroprevalence cross-sectional study in risk-stratified HCWs randomly selected from three main district hospitals in Oman.

Results

1078 HCWs were included, with an overall SARS-CoV-2 seroprevalence of 21%. The seropositivity rates in low-, variable-, and high-risk groups were 29%, 18%, and 17%, respectively (p-value < 0.001). The study found higher positivity in males (crude odds ratio [COR] 1.71, 95% confidence interval [CI] 1.28–2.3), and workers residing in high-prevalence areas (COR 2.09, 95% CI 1.42–3.07). Compared with doctors, workers from supporting services, administration staff, and nurses were more likely to test positive for SARS-CoV-2 antibodies (COR 9.81, 95% CI 5.26–18.27; 2.37, 95% CI 1.23–4.58; 2.08 95% CI 1.14–3.81). The overall rate of previously undetected infection was 12%, with higher values in low-risk HCWs. High district prevalence was a driving factor for seropositivity in the low-risk group (adjusted odds ratio [AOR] 2.36, 95% CI 1.0–5.59).

Conclusion

Low-risk supporting services workers can drive SARS-CoV-2 transmission in hospitals. More attention and innovation within this area will enhance the safety of health care during epidemics/pandemics.

Seroprevalence of SARS-CoV-2 antibodies, associated epidemiological factors and antibody kinetics among healthcare workers in Connecticut

BACKGROUND

Healthcare workers (HCWs) are at the front line of the ongoing coronavirus 2019 (COVID-19) pandemic. Comprehensive evaluation of the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) among HCWs in a large healthcare system could help to identify the impact of epidemiological factors and the presence of symptoms on the immune response to the infection over time.

AIM

To determine the seroprevalence of SARS-CoV-2-specific antibodies among HCWs, identify associated epidemiological factors and study antibody kinetics.

METHODS

A longitudinal evaluation of the seroprevalence and epidemiology of SARS-CoV-2-specific antibodies was undertaken in approximately 30,000 HCWs in the largest healthcare system in Connecticut, USA.

FINDINGS

At baseline, the prevalence of SARS-CoV-2 antibody among 6863 HCWs was 6.3% [95% confidence interval (CI) 5.7-6.9%], and was highest among patient care support (16.7%), medical assistants (9.1%) and nurses (8.2%), and lower for physicians (3.8%) and advanced practice providers (4.5%). Seroprevalence was significantly higher among African Americans [odds ratio (OR) 3.26 compared with Caucasians, 95% CI 1.77-5.99], in participants with at least one symptom of COVID-19 (OR 3.00, 95% CI 1.92-4.68), and in those reporting prior quarantine (OR 3.83, 95% CI 2.57-5.70). No symptoms were reported in 24% of seropositive participants. Among the 47% of participants who returned for a follow-up serological test, the seroreversion rate was 39.5% and the seroconversion rate was 2.2%. The incidence of re-infection in the seropositive group was zero.

CONCLUSION

Although there is a decline in the immunoglobulin G antibody signal over time, 60.5% of seropositive HCWs had maintained their seroconversion status after a median of 5.5 months.

A majority of uninfected adults show preexisting antibody reactivity against SARS-CoV-2

Preexisting cross-reactivity to SARS-CoV-2 occurs in the absence of prior viral exposure. However, this has been difficult to quantify at the population level due to a lack of reliably defined seroreactivity thresholds. Using an orthogonal antibody testing approach, we estimated that about 0.6% of nontriaged adults from the greater Vancouver, Canada, area between May 17 and June 19, 2020, showed clear evidence of a prior SARS-CoV-2 infection, after adjusting for false-positive and false-negative test results. Using a highly sensitive multiplex assay and positive/negative thresholds established in infants in whom maternal antibodies have waned, we determined that more than 90% of uninfected adults showed antibody reactivity against the spike protein, receptor-binding domain (RBD), N-terminal domain (NTD), or the nucleocapsid (N) protein from SARS-CoV-2. This seroreactivity was evenly distributed across age and sex, correlated with circulating coronaviruses' reactivity, and was partially outcompeted by soluble circulating coronaviruses' spike. Using a custom SARS-CoV-2 peptide mapping array, we found that this antibody reactivity broadly mapped to spike and to conserved nonstructural viral proteins. We conclude that most adults display preexisting antibody cross-reactivity against SARS-CoV-2, which further supports investigation of how this may impact the clinical severity of COVID-19 or SARS-CoV-2 vaccine responses.

Antibody Responses in COVID-19: A Review

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread worldwide as a severe pandemic. Although its seroprevalence is highly variable among territories, it has been reported at around 10%, but higher in health workers. Evidence regarding cross-neutralizing response between SARS-CoV and SARS-CoV-2 is still controversial. However, other previous coronaviruses may interfere with SARS-CoV-2 infection, since they are phylogenetically related and share the same target receptor. Further, the seroconversion of IgM and IgG occurs at around 12 days post onset of symptoms and most patients have neutralizing titers on days 14-20, with great titer variability. Neutralizing antibodies correlate positively with age, male sex, and severity of the disease. Moreover, the use of convalescent plasma has shown controversial results in terms of safety and efficacy, and due to the variable immune response among individuals, measuring antibody titers before transfusion is mostly required. Similarly, cellular immunity seems to be crucial in the resolution of the infection, as SARS-CoV-2-specific CD4+ and CD8+ T cells circulate to some extent in recovered patients. Of note, the duration of the antibody response has not been well established yet.

Provider Antibody Serology Study of Virus in the Emergency Room (PASSOVER) Study: Special Population COVID-19 Seroprevalence

Introduction

Limited data on the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers (HCW) are publicly available. In this study we sought to determine the seroprevalence of SARS-CoV-2 in a population of HCWs in a pediatric emergency department (ED).

Methods

We conducted this observational cohort study from April 14–May 13, 2020 in a pediatric ED in Orange County, CA. Asymptomatic HCW ≥18 years of age were included in the study. Blood samples were obtained by fingerstick at the start of each shift. The inter-sampling interval was ≤96 hours. The primary outcome was positive seroprevalence of SARS-CoV-2 as determined with an antibody fast detection kit (Colloidal Gold, Superbio, Timisoara, Romania) for the SARS-CoV-2 immunoglobulin M/immunoglobulin G (IgM/IgG) antibody.

Results

A total of 143 HCWs participated in the study. Overall SARS-CoV-2 seroprevalence was 10.5% (n = 15). Positive seroprevalence was classified as IgG only (4.9%), IgM+IgG (3.5%), or IgM only (2.1%). SARS-CoV-2 was detected by reverse transcription polymerase chain reaction RT-PCR in 0.7% of the overall study population (n = 1). Samples obtained on Day 1 indicated seropositivity in 4.2% of the study population (n = 6). Subsequent seroconversion occurred in 6.3% of participants (n = 9). The rate of seroconversion was linear with a rate of approximately one new case every two days, starting at Day 9 of the study.

Conclusion

We observed a linear rate of seroconversion to SARS-CoV-2–positive status among asymptomatic HCWs who underwent daily symptom surveys and temperature screens in an environment with universal source control. Rapid antibody testing may be useful for screening for SARS-CoV-2 seropositivity in high-risk populations, such as HCWs in the ED.

Prevalence of SARS-COV-2 positivity in 516 German intensive care and emergency physicians studied by seroprevalence of antibodies National Covid Survey Germany (NAT-COV-SURV)

Healthcare personnel are at risk to aquire the corona virus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated the prevalence of SARS-CoV-2 antibodies and positive nasopharyngeal reverse transcriptase polymerase-chain reaction (RT-PCR) tests in German intensive care and emergency physicians. Physicians attending intensive care and emergency medicine training courses between June 16^th and July 2^nd 2020 answered a questionnaire and were screened for SARS-CoV-2 antibodies via automated electrochemiluminiscence immunoassay. We recruited 516 physicans from all parts of Germany, 445/516 (86%) worked in high risk areas, and 379/516 (73%) had treated patients with COVID-19. The overall positive rate was 18/516 (3.5%), 16/18 (89%) had antibodies against SARS-COV-2, another 2 reported previous positive RT-PCR results although antibody testing was negative. Of those positive, 7/18 (39%) were unaware of their infection. A stay abroad was stated by 173/498 (35%), mostly in Europe. 87/516 (17%) reported a febrile respiratory infection after January 1^st 2020 which was related to SARS-CoV-2 in 4/87 (4.6%). Contact to COVID-19 positive relatives at home was stated by 22/502 (4.4%). This was the only significant risk factor for Covid-19 infection (Fisher´s exact test, p = 0.0005). N95 masks and eye protection devices were available for 87% and 73%, respectively. A total of 254/502 (51%) had been vaccinated against seasonal influenza. The overall SARS-CoV-2 infection rate of german physicians from intensive care and emergency medicine was low compared to reports from other countries and settings. This finding may be explained by the fact that the German health care system was not overwhelmed by the first wave of the SARS-CoV-2 pandemic.

Screening for SARS-CoV-2 via PCR and serological testing in asymptomatic healthcare workers

The prevalence and seroconversion rate of SARS-CoV-2 infection among asymptomatic health care workers in the US is unclear. Our study utilized real-time polymerase chain reaction (RT-PCR) SARS-CoV-2 testing and serological evaluation to detect IgG antibodies specific to SARS-CoV-2 antigens in asymptomatic health care workers. A total of 197 subjects with a mean age of 35 years were recruited into the study. While most (67%) reported prolonged contact with known COVID-19 patients, only 8 (4.2%) tested positive on RT-PCR and 23 (11.7%) had detectable levels of IgG antibody to SARS-CoV-2. Out of 19 subjects with detectable IgG antibody at week 1, 11 (57.9%) lost their antibody response by week 3. No statistically significant difference was found in baseline characteristics or exposure status between subjects with positive and negative results on RT-PCR or antibody positivity. In conclusion, we found a low incidence of PCR positivity for SARS-CoV-2 in a high-risk group. This likely demonstrates the effectiveness of proper personal protective equipment use and low transmission risk in health care settings. The detectable IgG antibody titer was low, and a significant portion of subjects lost their antibody response on repeat testing. This may mean that antibody response in asymptomatic patients is categorically different than in symptomatic hospitalized patients with COVID-19.

High Seroprevalence of SARS-CoV-2 among Healthcare Workers in a North Italy Hospital

Background: Healthcare workers (HCWs) have been the key players in the fight against the coronavirus disease 2019 (COVID-19) pandemic. The aim of our study was to evaluate the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG anti-bodies. Methods: We conducted a cross-sectional study among workers of two hospitals and Territorial Medical and Administrative services in Northern Italy. From 8 May to 3 June 2020, 2252 subjects were tested. Seroprevalence and 95% confidence interval (CI) were calculated for all individuals who were stratified by job title, COVID-19 risk of exposure, direct contact with patients, unit ward, and intensity of care. Results: Median age was 50 years, and 72% of subjects were female. The overall seroprevalence was 17.11% [95% CI 15.55–18.67]. Around 20% of healthcare assistants were seropositive, followed by physicians and nurses (16.89% and 15.84%, respectively). HCWs with high risk of exposure to COVID-19 were more frequently seropositive (28.52%) with respect to those with medium and low risks (16.71% and 12.76%, respectively). Moreover, personnel in direct contact had higher prevalence (18.32%) compared to those who did not (10.66%). Furthermore, the IgG were more frequently detected among personnel of one hospital (19.43%). Conclusion: The high seroprevalence observed can be partially explained by the timing and the population seroprevalence; the study was conducted in an area with huge spread of the infection.