Asymptomatic Healthcare Workers Research Articles

Anti-SARS-COV-2 antibodies Amongst Asymptomatic Healthcare Workers and students of Tertiary Care hospital and Medical School in Pakistan

Introduction: Coronavirus emerged as a pandemic in 2019 with the SARS COV 2 virus infecting people worldwide. Although PCR successfully detected symptomatic patients, asymptomatic patients remained undetected due to limitation of resources. The objective of the study was to determine the prevalence of IgM and IgG antibodies in the faculty, staff, and MBBS students in Medical school and tertiary care hospital, Pakistan.
 Material and Methods: A cross-sectional study was conducted on 500 asymptomatic healthy subjects, from September to December 2020 in Biochemistry department Shalamar Medical and Dental College (SMDC). Rapid antibody test was used to determine the presence of IgM and IgG antibodies in the subjects. Those found IgM positive were validated by COVID 19 detection by Polymerase Chain Reaction.
 Results: Anti-SARS-COV 2 antibodies was observed in 19.6 % of 500 asymptomatic subjects. Significant reactive cases were identified in hospital staff (27.5%) compared to hospital faculty (23.4%), medical students (21.4%), college faculty (6.12%) followed by college staff (3.06%). Significant reactive cases (47.9%) were identified in middle age group i.e. between 31 to 45 years. IgG was more prevalent than IgM and 2% of the subjects showed coagulation disorders who were both IgG and IgM positive.
 Conclusion: Prevalence of 19.6% of Anti-SARS-COV 2 antibodies was observed in asymptomatic subjects. Prevalence was more in males, people in the middle age group i.e. 31 to 45 years and in hospital staff and faculty.
 Recommendations: Based on the study it is recommended that Rapid COVID 19- SRAC-2 antibody test, which is cost effective and rapid method may be used to detect the COVID 19 in developing countries with limited resources.

Central Serous Retinopathy in a Post COVID-19 Asymptomatic Healthcare Worker at a Tertiary Care Hospital: A Unique Case Report

Aim: Early detection and management of stress-related Central Serous Retinopathy caused due to COVID-19.
 Background: CSR has been associated with stress and is usually self-resolving. COVID-19 is known to induce psychological stress and its effects are many, one of them may be CSR. The importance of understanding the psychological impact of the disease, its consequences, and the counseling of even asymptomatic patients to ensure stress reduction needs to be understood by the treating physician.
 Case Report and Discussion: We report the first case of CSR associated with COVID-19 related stress in an asymptomatic health care worker and the follow-up and treatment plan for this case. It has been shown that unfavourable psychic factors influence endogenous hormonal secretion which in turn increases the levels of corticosteroids and catecholamines which have been found to induce CSR.
 Conclusion: This study highlights the importance of understanding the psychological effect of the pandemic and recognising this and early treatment will reduce the ill effects of the stress induced by COVID-19.

Coronavirus disease 2019 (COVID-19) mRNA vaccine effectiveness in asymptomatic healthcare workers.

Coronavirus disease 2019 (COVID-19) mRNA vaccine effectiveness in asymptomatic healthcare workers.

The Effect of Test Timing on the Probability of Positive SARS-CoV-2 Swab Test Results: Mixed Model Approach.

BackgroundDuring the COVID-19 pandemic, swab tests proved to be effective in containing the infection and served as a means for early diagnosis and contact tracing. However, little evidence exists regarding the correct timing for the execution of the swab test, especially for asymptomatic individuals and health care workers.ObjectiveThe objective of this study was to analyze changes in the positive findings over time in individual SARS-CoV-2 swab tests during a health surveillance program.MethodsThe study was conducted with 2071 health care workers at the University Hospital of Verona, with a known date of close contact with a patient with COVID-19, between February 29 and April 17, 2020. The health care workers underwent a health surveillance program with repeated swab tests to track their virological status. A generalized additive mixed model was used to investigate how the probability of a positive test result changes over time since the last known date of close contact, in an overall sample of individuals who tested positive for COVID-19 and in a subset of individuals with an initial negative swab test finding before being proven positive, to assess different surveillance time intervals.ResultsAmong the 2071 health care workers in this study, 191 (9.2%) tested positive for COVID-19, and 103 (54%) were asymptomatic with no differences based on sex or age. Among 49 (25.7%) cases, the initial swab test yielded negative findings after close contact with a patient with COVID-19. Sex, age, symptoms, and the time of sampling were not different between individuals with an initial negative swab test finding and those who initially tested positive after close contact. In the overall sample, the estimated probability of testing positive was 0.74 on day 1 after close contact, which increased to 0.77 between days 5 and 8. In the 3 different scenarios for scheduled repeated testing intervals (3, 5, and 7 days) in the subgroup of individuals with an initially negative swab test finding, the probability peaked on the sixth, ninth and tenth, and 13th and 14th days, respectively.ConclusionsSwab tests can initially yield false-negative outcomes. The probability of testing positive increases from day 1, peaking between days 5 and 8 after close contact with a patient with COVID-19. Early testing, especially in this final time window, is recommended together with a health surveillance program scheduled in close intervals.

Prospective Observational COVID-19 Screening and Monitoring of Asymptomatic Cancer Center Health-Care Workers with a Rapid Serological Test.

Health-care workers (HCW) are at high risk for SARS-CoV-2 infection and, if asymptomatic, for transmitting the virus to fragile cancer patients. We monitored all asymptomatic HCWs of a cancer institute (94% of all employees agreed to enter the study) with the rapid serological test, VivaDiagTM, identifying SARS-CoV-2 associated-IgM/IgG. The tests were performed at time 0 (n = 606) and after 14 days (n = 393). Overall, the VivaDiagTM results of nine HCWs (1.5%) were positive, with one confirmed to be SARS-CoV-2-positive after oropharyngeal swab testing by RT-PCR. At time 0, all nine cases showed IgM expression while IgG was detected in only one. After 14 days, IgM persisted in all the cases, while IgG became evident in four. A chemiluminescence immunoassay (CLIA) confirmed IgM positivity in 5/13 VivaDiagTM positive cases and IgG positivity in 4/5 VivaDiagTM positive cases. Our study suggests that the VivaDiagTM test can be of help in identifying SARS-CoV-2 infected people in cohorts of subjects with a high prevalence.

Hydroxychloroquine as prophylaxis when treating patients with coronavirus disease 2019 – Perception of frontline health care workers in South India

Objectives: In March 2020, the Indian Council of Medical Research (ICMR) recommended the use of hydroxychloroquine (HCQ) for prophylaxis in asymptomatic health care workers who care for suspected or confirmed patients and household contacts of confirmed patients with coronavirus disease 2019 (COVID-19). This recommendation was received by health-care practitioners with mixed opinions. The objectives of the study were to explore the views of frontline health-care practitioners (physicians, nurses, and physician assistants) in South India related to the ICMR recommendation of HCQ prophylaxis. Material and Methods: The survey research design was used to conduct this study. A ten-item electronic survey was developed based on the research question. The survey link was shared with frontline health-care practitioners in South India through email and WhatsApp messages identified through convenience sampling. Furthermore, the recipients were requested to forward the link to other frontline health-care professionals in their network (snowball sampling). Data were collected from April 16, 2020, to May 7, 2020. Results: The number of responses received was 132. Of 80 respondents who treated or anticipate treating patients with COVID-19, only 29 respondents reported that they complied with the ICMR’s HCQ chemoprophylaxis recommendation. Participants expressed concerns about the side effects and lack of conclusive evidence. Conclusion: Frontline health care workers in South India have mixed opinions with regard to the safety of HCQ prophylaxis. To promote the acceptance of and successful implementation of prophylaxis recommendations, it is essential that health authorities consider research evidence and seek stakeholder input before finalizing recommendations.

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

IntroductionLimited 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).MethodsWe 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.ResultsA 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.ConclusionWe 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.

SARS-CoV-2 Transmission Risk to Household and Family Contacts by Vaccinated Healthcare Workers.

SARS-CoV-2 Transmission Risk to Household and Family Contacts by Vaccinated Healthcare Workers.

SARS-CoV-2 Antibody Screening in Healthcare Workers in Non-Infectious Hospitals in Two Different Regions of Southern Poland (Upper Silesia and Opole Voivodeships): A Prospective Cohort Study.

(1) Background: Detection of asymptomatic or subclinical human coronavirus SARS-CoV-2 infection in healthcare workers (HCWs) is crucial for understanding the overall prevalence of the new coronavirus and its infection potential in public (non-infectious) healthcare units with emergency wards. (2) Methods: We evaluated the host serologic responses, measured with semi-quantitative ELISA tests (IgA, IgG, IgM abs) in sera of 90 individuals in Hospital no. 4 in Bytom, 84 HCWs in the University Hospital in Opole and 25 in a Miasteczko Śląskie local surgery. All volunteers had negative RT-PCR test results or had not had the RT-PCR test performed within 30 days before sampling. The ELISA test was made at two different time points (July/August 2020) with a 2-weeks gap between blood collections to avoid the “serological window” period. (3) Results: The IgG seropositivity of asymptomatic HCWs varied between 1.2% to 10% (Opole vs. Bytom, p < 0.05; all without any symptoms). IgA seropositivity in HCWs was 8.8% in Opole and 7.14% in Bytom. IgM positive levels in HCWs in Opole and Bytom was 1.11% vs. 2.38%, respectively. Individuals with IgA and IgM seropositivity results were observed only in Opole (1.19%). More studies are needed to determine whether these results are generalizable to other populations and geographic as well as socio-demographic locations. (4) Conclusions: 100% of IgG(+) volunteers were free from any symptoms of infection in the 30 days before first or second blood collection and they had no awareness of SARS-CoV-2 infection. Asymptomatic HCWs could spread SARS-CoV-2 infection to other employees and patients. Only regular HCWs RT-PCR testing can reduce the risk of SARS-CoV-2 spreading in a hospital environment. The benefit of combining the detection of specific IgA with that of combined specific IgM/IgG is still uncertain.

Seroprevalence of hospital staff in a province with zero COVID-19 cases

COVID-19 seroprevalence data, particularly in less developed countries with a relatively low incidence, has been scant. We aimed to explore the seroprevalence of hospital staff in the area with zero confirmed COVID-19 case to shed light on the situation of COVID-19 infection in zero or low infection rate countries where mass screening was not readily available. A locally developed rapid immunoglobulin M (IgM)/immunoglobulin G (IgG) test kit was used for hospital staff screening of Ranong hospital which is located in a province with zero COVID-19 prevalence in Thailand from 17th April to 17th May 2020. All staff was tested, 100 of which were randomly invited to have a repeating antibody test in one month. (Thai Clinical Trials Registry: TCTR20200426002). Of 844 hospital staff, 82 were tested twice one month apart (response rate for repeating antibody test 82%). Overall, 0.8% of the participants (7 of 844) had positive IgM, none had positive IgG. Female staff had 1.0% positive IgM (95% CI: 0.5-2.1%) while male had 0.5% positive IgM (95% CI: 0.1-2.6%). No participants with a history of travel to the high-risk area or close contact with PCR-confirmed COVID-19 case developed SARS-CoV-2 antibodies. Among 844 staff, 811 had no symptoms and six of them developed IgM seropositive (0.7%) while 33 had minor symptoms and only one of them developed IgM seropositive (3.0%). No association between SARS-CoV-2 IgM status and gender, history of travel to a high-risk area, close contact with PCR-confirmed or suspected COVID-19 case, presence of symptoms within 14 days, or previous PCR status was found. None of the hospital staff developed SARS-CoV-2 IgG. COVID-19 antibody test could detect a considerable number of hospital staff who could be potential silent spreaders in a province with zero COVID-19 cases. Accurate antibody testing is a valuable screening tool, particularly in asymptomatic healthcare workers. Trial registration: This study was approved by the Institutional Review Board of Chulalongkorn University (IRB No.236/63) and the Institutional Review Board of Ranong Hospital. (Thai Clinical Trials Registry: TCTR20200426002).

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.

Factors Associated with COVID-19 and Asymptomatic Carriage in Healthcare Workers of a COVID-19 Hospital.

Risk factors for coronavirus disease (COVID-19) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) asymptomatic carriage (AC) in healthcare workers (HCWs) have been scarcely characterized. The objective of the study was to study factors associated with COVID-19 and AC in HCWs of a COVID-19 academic medical center. This is a case-control study. Cases were either symptomatic or asymptomatic HCWs with a positive SARS-CoV-2 polymerase chain reaction (PCR) test result between March 16 and May 21 of 2020. Adjusted odds ratios (aOR) were calculated by means of multivariable logistic regression. In addition, each subject was followed for 14 days to inform outcomes. One hundred thirty of 249 (52.2%) symptomatic HCWs had COVID-19; 10 were hospitalized but none died. Of 987 asymptomatic HCWs,37 (3.7%) were AC; 6 of the remaining 950 asymptomatic HCWs with a negative PCR test result were found to be presymptomatic COVID-19 cases the following 14 days. Nurses were more frequently present in the COVID-19 group (51.5% vs. 37.0%), but multivariable analysis rendered non-significant results. After adjustment for age, comorbidities, and working place, factors found to be associated with AC were: working in wards as a nurse (aOR = 9.19, 95% confidence interval [CI] = 1.05-80.22, p = 0.045), kitchen personnel (aOR = 4.09, 95% CI = 1.55-10.83, p = 0.005), and being a physician (aOR = 0.12, 95% CI = 0.03-0.54, p = 0.006). HCW category was the predominant factor associated with AC of SARS-CoV-2 in this study.

Mitigating staff shortages: Risk of permitting healthcare workers to return to work after coronavirus disease 2019 (COVID-19) exposure.

Critical staffing shortages have compelled hospitals to allow healthcare workers (HCWs) with low-risk COVID-19 exposures to continue to work. We performed SARS-CoV-2 PCR surveillance of asymptomatic HCWs allowed to work with masks after a low-risk COVID-19 exposure. A total of 66 HCWs participated and 5 (7.6%) were found to be PCR positive. Asymptomatic HCWs with low-risk exposures may represent a significant transmission risk.

SARS-CoV-2 RT-PCR positivity and antibody prevalence among asymptomatic hospital-based health care workers.

BackgroundThe level of asymptomatic infection with SARS-CoV-2 could be substantial and among health care workers (HCWs) a source of continuing transmission of the virus to patients and co-workers.ObjectivesMeasure the period prevalence of SARS-CoV-2 PCR positivity and seroprevalence of SARS-CoV-2 IgG antibodies among a random sample of asymptomatic health system hospital-based health care workers (HCWs) 6½ -15½ weeks after 4/5/2020, the peak of the first surge of COVID-19 admissions.ResultsOf 524 eligible and consented participants from four metropolitan hospitals, nasopharyngeal swabs were obtained from 439 (83.8 %) and blood from 374 (71.4 %). Using PCR nucleic acid-based amplification (NAAT) methods, the period prevalence of SARS-CoV-2 infection was 0.23 % (95 % confidence interval (CI) 0.01 %–1.28 %; 1/439) from 5/21/20−7/16/20. The seroprevalence of SARS-CoV-2 IgG antibodies from June 17-July 24, 2020 was 2.41 % (95 % CI 1.27 %–4.51 %; 9/374). Those who were reactive were younger (median age 36 versus 44 years; p = 0.050), and those with self-reported Hispanic/Latino ethnicity had a higher seroprevalence (2/12 = 16.7 % versus 7/352 = 2.0 %; p = 0.051). There were no significant differences by sex, race, residence, hospital, unit or job type. The one employee who was found to be PCR test positive in this study was also reactive for IgG antibodies, tested 27 days later.ConclusionsThe period prevalence of PCR positivity to SARS-CoV-2 and IgG seroprevalence was unexpectedly low in asymptomatic HCWs after a peak in COVID-19 admissions and the establishment of state and institutional infection control policies, suggesting that routine screening tests while community prevalence is relatively low would produce a minimal yield.

Durability of Viral Neutralization in Asymptomatic Coronavirus Disease 2019 for at Least 60 Days.

A cohort consisting of asymptomatic healthcare workers donated temporal serum samples after infection with severe acute respiratory syndrome coronavirus 2. Analysis shows that all asymptomatic healthcare workers had neutralizing antibodies, that these antibodies persist for ≥60 days, and that anti-spike receptor-binding domain immunoglobulin G levels were correspondingly durable over the same time period.

Olfactory Dysfunction is Associated with More Severe Clinical Course in COVID-19.

To perform a quantitative olfactory test in positive COVID19 RT-PCR admitted patients and asymptomatic ones, to evaluate the association between hyposmia and disease severity. This is a Cross sectional study. Ninety-one patients including 68 inpatients and 23 asymptomatic healthcare workers with positive COVID-19 RT-PCRs. Methods: Demographics and clinical characteristics were collected. Iran Smell Identification Test (IR-SIT), a highly accurate 6-odorant test was used to evaluate the reliability of self-reported hyposmia and determine the correlation of the measured olfactory dysfunction with disease severity. Twenty-two of 91 patients (24%) reported hyposmia, while 41/91 (45%) patients had measurable olfactory dysfunction (IR-SIT score 1–4, p < 0.05). Mean age of the 68 inpatients and 23 asymptomatic patients were 43.97 ± 16.13 years; M:F 43:25, and 43.87 ± 12.76 years; M:F 8:15 respectively. Of 68 patients, 20 were graded as severe, and 48/68 had mild course of disease. IR-SIT detected hyposmia in 80% of patients with severe disease, and 50% with mild disease, respectively. The risk of disease severity was significantly increased for patients with olfactory dysfunction and was detected 4 times higher when compared to patients with mild disease (OR 4, 95% CI: 1.166–13.728, p = 0.028). Olfactory Dysfunction was present in 80% of patients with severe course. The risk of disease severity is significantly increased with olfactory dysfunction in admitted patients.

Effectiveness of Preventive Measures in Keeping Low Prevalence of SARS-CoV-2 Infection in Health Care Workers in a Referral Children’s Hospital in Southern Italy

The coronavirus disease 2019 (COVID-19) pandemic now represents a major threat to public health. Health care workers (HCW) are exposed to biological risk. Little is currently known about the risk of HCW operating in pediatric wards for SARS-CoV-2 infection. The aim is to assess the prevalence of SARS-CoV-2 infection in HCW in a third-level children’s hospital in Southern Italy. An observational cohort study of all asymptomatic HCW (physician, technicians, nurses, and logistic and support operators) was conducted. HCW were screened, on a voluntary basis, for SARS-CoV-2 by RT-PCR on nasopharyngeal swab performed during the first wave of COVID-19. The study was then repeated, with the same modalities, at a 7-month interval, during the “second wave” of the COVID-19 pandemic. At the initial screening between 7 and 24 April 2020, 525 HCW were tested. None of them tested positive. At the repeated screening, conducted between 9 and 20 November 2020, 627 HCW were tested, including 61 additional ones resulting from COVID-emergency recruitment. At this second screening, eight subjects (1.3%) tested positive, thus being diagnosed as asymptomatic carriers of SARS-CoV-2. They were one physician, five nurses, and two HCW from the logistic/support services. They were employed in eight different wards/services. In all cases, the epidemiological investigation showed convincing evidence that the infection was acquired through social contacts. The study revealed a very low circulation of SARS-CoV-2 infection in HCW tested with RT-PCR. All the infections documented in the second wave of epidemic of SARS-CoV-2 were acquired outside of the workplace, confirming that in a pediatric hospital setting, HCW education, correct use of personal protective equipment, and separation of the COVID-patient pathway and staff flow may minimize the risk derived from occupational exposure.

Reverse transcription loop-mediated isothermal amplification (RT-LAMP) for point-of-care detection of SARS-CoV-2: a clinical study to evaluate agreement with RT-qPCR

BackgroundThe global COVID-19 pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the need for rapid, accurate, and accessible diagnostics to enable timely treatment and outbreak control. However, current diagnostic tests based on RT-qPCR are insufficient to meet the global testing demand because of their high cost and complexity and supply chain shortages. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is a promising alternative to RT-qPCR because of its sensitivity, speed, and robustness to sample inhibitors. Here, we describe the development and optimisation of a sample-to-answer workflow, including a simple lysis and inactivation protocol that provides results in <1h, using inexpensive and readily available reagents. Further, we assess the sensitivity and specificity of the developed RT-LAMP assay against a RT-qPCR. MethodsWe collected samples from asymptomatic healthcare workers at The University of Texas MD Anderson Cancer Center and inpatients at Lyndon B Johnson Hospital in Houston, TX, USA. Nasopharyngeal swabs were collected by medical providers and were placed directly into 300 μL of an optimised lysis buffer. Samples were heat inactivated at 95°C for 5 mins before direct amplification in a RT-LAMP assay using previously published primer sets. Heating and real-time monitoring was performed using a Bio-Rad CFX96 thermocycler and an Axxin T8-ISO, a benchtop fluorimeter designed for point-of-care settings. We compared results from the RT-LAMP test with standard-of-care RT-qPCR results on paired nasopharyngeal swabs collected into Universal Viral Transport Media. FindingsThe developed RT-LAMP assay demonstrated a limit of detection of 4–5 virions/μL. The test requires a swab, two tubes, prepared lysis buffer, a heat block, pipettes, RT-LAMP reagents, and the real-time fluorimeter. Samples were collected between April 14, 2020 and Aug 12, 2020, and results from 74 enrolled participants were analysed in the optimised workflow. Thirty nine participants tested positive for SARS-CoV-2 and 35 participants tested negative in the hospital-administered RT-qPCR test. All 74 nasopharyngeal swab eluates were tested with our assay on the Bio-Rad CFX96; 72 nasopharyngeal swab eluates were also tested on the Axxin T8-ISO. The developed assay showed sensitivity of 92·31% and 91·89% when tested on the CFX96 and T8, respectively, and specificity of 91·43% and 97·89%, respectively. InterpretationRT-LAMP could be used for SARS-CoV-2 testing and overcomes the challenges of adapting an assay to a point-of-care instrument. Further, the reduced instrumentation cost and complexity, along with the simple workflow, highlight the potential for implementation of RT-LAMP for SARS-CoV-2 testing in resource-limited settings. FundingUSAID, IAVI, and Rice University.

Comparison of SARS-CoV-2 infections in healthcare workers with high and low exposures to Covid-19 patients in a Norwegian University Hospital

Introduction A year into the pandemic, the knowledge of SARS-CoV-2 infection risks among healthcare workers remains limited. In this cross-sectional study, we examined whether healthcare workers with high exposure to Covid-19 patients had a higher risk of SARS-CoV-2 infection than other healthcare workers in a Norwegian University Hospital. We also investigated the prevalence of asymptomatic healthcare workers in a ward with a SARS-CoV-2 outbreak. Methods Healthcare workers from five wards at Akershus University Hospital were included between May 11 and June 11, 2020. Blood samples were analyzed for SARS-CoV-2 antibodies and seroprevalences compared between participants with high and low exposure to Covid-19 patients. Demographic data and SARS-CoV-2 infection risk factors were recorded in a questionnaire. Naso-/oropharyngeal swabs from participants from the outbreak ward were analyzed by reverse transcriptase-polymerase chain reaction. Results 360/436 (82.6%) healthcare workers participated. 9/262 (3.4%) participants from wards with high exposure to Covid-19 patients were SARS-CoV-2 seropositive versus 3/98 (3.1%) from wards with low exposure (OR 1.13; 95%CI 0.3–4.26, p = .861). SARS-CoV-2 antibodies were found in 11/263 (4.2%) participants who had worked one or more shifts caring for Covid-19 patients versus in 1/85 (1.2%) without any known occupational Covid-19 exposure (OR 3.67; 95%CI 0.46–29.06, p = .187). SARS-CoV-2 was detected in naso-/oropharyngeal swabs from 2/78 (2.6%) participants. Conclusion We found no significantly increased risk of SARS-CoV-2 infection in healthcare workers with high exposure to COVID-19 patients. Five healthcare workers had either serologic or molecular evidence of past or present unrecognized SARS-CoV-2 infection.

Prospective observational study and serosurvey of SARS-CoV-2 infection in asymptomatic healthcare workers at a Canadian tertiary care center.

Health care workers (HCWs) are at higher risk for SARS-CoV-2 infection and may play a role in transmitting the infection to vulnerable patients and members of the community. This is particularly worrisome in the context of asymptomatic infection. We performed a cross-sectional study looking at asymptomatic SARS-CoV-2 infection in HCWs. We screened asymptomatic HCWs for SARS-CoV-2 via PCR. Complementary viral genome sequencing was performed on positive swab specimens. A seroprevalence analysis was also performed using multiple assays. Asymptomatic health care worker cohorts had a combined swab positivity rate of 29/5776 (0.50%, 95%CI 0.32-0.75) relative to a comparative cohort of symptomatic HCWs, where 54/1597 (3.4%) tested positive for SARS-CoV-2 (ratio of symptomatic to asymptomatic 6.8:1). SARS-CoV-2 seroprevalence among 996 asymptomatic HCWs with no prior known exposure to SARS-CoV-2 was 1.4-3.4%, depending on assay. A novel in-house Coronavirus protein microarray showed differing SARS-CoV-2 protein reactivities and helped define likely true positives vs. suspected false positives. Our study demonstrates the utility of routine screening of asymptomatic HCWs, which may help to identify a significant proportion of infections.