Testing of Healthcare Workers Exposed to COVID19 with Rapid Antigen Detection

There is a need to develop safe and cost-effective ways to test healthcare workers for COVID19. Here we describe a rapid antigen testing strategy in a cohort of 497 Healthcare workers exposed to SARS-CoV-2 that can be applied by systems facing a surge of COVID19 cases, increased exposures in their workforce and limited RT-PCR availability. Our findings support an expanded use for antigen testing beyond its current indication and highlights the importance of further studying this modality for the diagnosis of COVID19 on asymptomatic individuals.

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Assessment of the National Test Strategy on the Development of the COVID-19 Pandemic in Denmark

Epidemiologia ◽

10.3390/epidemiologia2040037 ◽

2021 ◽

Vol 2 (4) ◽

pp. 540-552

Author(s):

Peter Kamp Busk ◽

Thomas Birk Kristiansen ◽

Allan Engsig-Karup

Keyword(s):

Educational Institutions ◽

Free Access ◽

Testing Strategy ◽

Rt Pcr ◽

Test Strategy ◽

Testing Frequency ◽

National Test ◽

The Relationship ◽

Antigen Testing

During the COVID-19 pandemic, Denmark has pursued a mass testing strategy culminating in the testing of 12.167 individuals per 100,000 inhabitants per day during the spring of 2021. The strategy included free access to COVID-19 testing, and since 2021, compulsory documentation for negative tests or vaccination has been required for access to workplace, educational institutions, restaurants, and many other places. Testing and subsequent isolation if testing was positive were voluntary. The present study provides an analysis of whether testing frequency in Denmark showed any correlation to hospitalizations throughout the relevant stages of the pandemic. Mass testing was found not to correlate significantly with the number of hospitalizations during the pandemic. Interestingly, during the highest level of testing in spring 2021 the fraction of positive tests increased slightly; thus, the Danish mass testing strategy, at its best, failed to reduce the prevalence of COVID-19. Furthermore, the relationship between positives in antigen testing and in rt-PCR testing indicated that many patients were not tested early in their infection when the risk of transmission was at the highest. In conclusion, the Danish mass testing strategy for COVID-19 does not appear to have a detectable correlation to the number of hospitalizations due to COVID-19.

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Evaluating the Relationship between Cycle Threshold Values and Reported COVID-19 Symptoms among Healthcare Workers

Antimicrobial Stewardship & Healthcare Epidemiology ◽

10.1017/ash.2021.35 ◽

2021 ◽

Vol 1 (S1) ◽

pp. s19-s20

Author(s):

Mindy Sampson ◽

Catherine Passaretti ◽

Jennifer Priem ◽

Shelley Kester ◽

Kristin Fischer ◽

...

Keyword(s):

Symptom Onset ◽

Healthcare Workers ◽

Current Understanding ◽

Linear Regression Models ◽

Rt Pcr ◽

Cycle Threshold ◽

E Gene ◽

Asymptomatic Individuals ◽

Number Of Cycles ◽

The Relationship

Background: SARS-CoV-2 detected by reverse transcription polymerase chain reaction (RT-PCR) can persist for weeks to months in some individuals. Cycle threshold (Ct) values represent the number of cycles needed to amplify viral ribonucleic acid (RNA) to reach a detectable level. As such, Ct values are inversely related to the amount of virus in a sample. As knowledge of SARS-CoV-2 viral dynamics continues to evolve, understanding the relationship between Ct values, type of symptoms, and timing of symptom onset can help determine when infected individuals are most likely to be infectious. Methods: We conducted a retrospective cohort study of 1,027 healthcare workers (HCWs) who tested positive for SARS-CoV-2 by RT-PCR from nasopharyngeal specimens between June 27, 2020, and September 21, 2020. All HCWs were interviewed within 72 hours of their diagnosis for symptom history. Due to multiple PCR platforms being in use in our facility, only 360 HCWs (35%) had Ct values available for analysis. Multivariate linear regression models examined the effect of COVID-19–related symptoms and timing of symptom onset to test on Ct values. Results: The most frequently reported symptoms were congestion (55.6%), cough (50.3%), and headache (46.7%). Other symptoms less commonly reported were fatigue (36.7%), loss of taste or smell (36.4%), fever (35.4%), muscle aches (33.3%), sore throat (27.4%), and diarrhea (26.7%). Symptomatic HCWs (88.3% of sample) had lower Ct values (ORF-1 M = 22.66, SD = 5.17; E-Gene M = 24.34, SD = 6.60) than asymptomatic individuals (ORF-1 M = 25.46, SD = 6.06; E-Gene M = 29.34, SD = 7.96). Of all symptoms measured, only presence of fever, congestion, and muscle aches predicted significantly lower Ct values. Mean Ct values decreased 2 days prior to symptom onset, were lowest the day of symptom onset, then increased in a curvilinear fashion. There were no significant 2-way interactions between symptoms and time of symptom onset to testing. Conclusions: The curvilinear pattern of Ct values over time from symptom onset are consistent with disease progression patterns and support current understanding of infectivity being highest 2 days prior to symptom onset through day 8. Presence of fever, congestion, and muscle aches are significantly correlated with lower Ct values, suggesting that these symptoms are associated with higher viral load. Although Ct values are not without limitations, our findings support the current understanding that presymptomatic and symptomatic individuals, particularly those with fever, congestion, and muscle aches, may pose higher risk of transmission to others.Funding: NoDisclosures: None

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Comparative analysis of three point-of-care lateral flow immunoassays for detection of anti-SARS-CoV-2 antibodies in COVID-19 confirmed healthcare workers

10.1101/2020.11.11.20229914 ◽

2020 ◽

Author(s):

Danielle Dias Conte ◽

Joseane Mayara Almeida Carvalho ◽

Luciano Kleber de Souza Luna ◽

Klinger Soares Faíco-Filho ◽

Ana Helena Perosa ◽

...

Keyword(s):

Healthcare Workers ◽

Large Scale ◽

Point Of Care ◽

Antibody Test ◽

Cost Effective ◽

Lateral Flow ◽

Rt Pcr ◽

Serum Samples ◽

Igg Antibody ◽

Serological Tests

AbstractSince the Coronavirus Disease 2019 (COVID-19) pandemic, Brazil has the third-highest number of confirmed cases and the second-highest number of recovered patients. SARS-CoV-2 detection by real-time RT-PCR is the gold standard in certified infrastructured laboratories. However, for large-scale testing, diagnostics should be fast, cost-effective, widely available, and deployed for the community, such as serological tests based on lateral flow immunoassay (LFIA) for IgM/IgG detection. We evaluated three different commercial point-of-care (POC) LFIAs for anti-SARS-CoV-2 IgM and IgG detection in capillary whole blood of 100 healthcare workers (HCW) previously tested by RT-PCR: 1) COVID-19 IgG/IgM BIO (Bioclin, Brazil), 2) Diagnostic kit for IgM/IgG Antibody to Coronavirus (SARS-CoV-2) (Livzon, China); and 3) SARS-CoV-2 Antibody Test (Wondfo, China). A total of 84 positives and 16 negatives HCW were tested. The data was also analyzed by the number of days post symptoms (DPS) in three groups: <30 (n=26), 30-59 (n=42), and >59 (n=16). Overall detection was 85.71%, 47.62%, and 44.05% for Bioclin, Livzon, and Wondfo, respectively, with a specificity of 100%, and 98.75% for Livzon on storage serum samples. Bioclin was more sensitive (p<0.01), regardless of the DPS. Thus, the Bioclin can be used as a POC test to monitor SARS-CoV-2 seroconversion in HCW.

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EXPRESS: Performance characteristics of five SARS-CoV-2 serological assays: clinical utility in healthcare workers

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/00045632211012728 ◽

2021 ◽

pp. 000456322110127

Author(s):

Emma Heffernan ◽

Lisa Kennedy ◽

Margaret Hannan ◽

Navneet Ramlaul ◽

Stephanie Denieffe ◽

...

Keyword(s):

Sensitivity And Specificity ◽

Acute Infection ◽

Elisa Assay ◽

Testing Strategy ◽

Rt Pcr ◽

Important Indicator ◽

Study Objective ◽

Previous Infection ◽

Asymptomatic Individuals ◽

Prior Infection

Study Objective: SARS-CoV-2 which causes Coronavirus disease (COVID-19) continues to cause significant morbidity and mortality. The diagnosis of acute infection relies on RT-PCR based viral detection. The objective of this study was to evaluate the optimal serological testing strategy for anti-SARS-CoV-2 antibodies which provides an important indicator of prior infection and potential short-term immunity. Methods: The sensitivity and specificity of four different ELISA assays (Euroimmun IgG, Euroimmun NCP-IgG, Fortress and DIAsource) and one CLIA assay (Roche ELECSYS) were evaluated in 423 samples; 137 patients with confirmed RT-PCR COVID-19 infection (true positives), and 100 pre-pandemic samples collected prior to October 2019 (true negatives). A further 186 samples were collected from healthcare staff and analysed by all five assays. Results: The Fortress ELISA assay demonstrated the highest sensitivity and specificity followed by the Roche ECLIA assay. The highest overall sensitivity came from the assays that measured total antibody (IgM-IgG combined) and the three assays that performed the best (Fortress, Roche, Euroimmun IgG) all have different antigens as their target proteins which suggests that antigen target does not affect assay performance. In mildly symptomatic participants with either a negative RT-PCR or no RT-PCR performed, 16.76% had detectable antibodies suggesting previous infection. Conclusions: We recommend a combined testing strategy utilising assays with different antigenic targets using the fully automated Roche ECLIA assay and confirming discordant samples with the Fortress Total Antibody ELISA assay. This study provides an important indicator of prior infection in symptomatic and asymptomatic individuals.

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SARS-CoV-2 Antigen Detection to Expand Testing Capacity for COVID-19: Results from a Hospital Emergency Department Testing Site

Diagnostics ◽

10.3390/diagnostics11071211 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1211

Author(s):

Giulia Menchinelli ◽

Giulia De Angelis ◽

Margherita Cacaci ◽

Flora Marzia Liotti ◽

Marcello Candelli ◽

...

Keyword(s):

Emergency Department ◽

Predictive Value ◽

Tertiary Care ◽

Antigen Detection ◽

Care Hospital ◽

Hospital Emergency Department ◽

Rt Pcr ◽

Hospital Emergency ◽

Asymptomatic Patients ◽

Antigen Testing

Background: SARS-CoV-2 antigen detection has currently expanded the testing capacity for COVID-19, which yet relies on the SARS-CoV-2 RNA RT-PCR amplification. Objectives: To report on a COVID-19 testing algorithm from a tertiary care hospital emergency department (ED) that combines both antigen (performed on the ED) and RT-PCR (performed outside the ED) testing. Methods: Between December 2020 and January 2021, in a priori designated, spatially separated COVID-19 or non-COVID-19 ED areas, respectively, symptomatic or asymptomatic patients received SARS-CoV-2 antigen testing on nasopharyngeal swab samples. Antigen results were promptly accessible to guide subsequent, outside performed confirmatory (RT-PCR) testing. Results: Overall, 1083 (100%) of 1083 samples in the COVID-19 area and 1815 (49.4%) of 3670 samples in the non-COVID-19 area had antigen results that required confirmation by RT-PCR. Antigen positivity rates were 12.4% (134/1083) and 3.7% (66/1815), respectively. Compared to RT-PCR testing results, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of antigen testing were, respectively, 68.0%, 98.3%, 88.8%, and 94.1% in the COVID-19 area, and 41.9%, 97.3%, 27.3%, and 98.6% in non-COVID-19 area. Practically, RT-PCR tests were avoided in 50.6% (1855/3670) of non-COVID-19 area samples (all antigen negative) from patients who, otherwise, would have needed antigen result confirmation. Conclusions: Our algorithm had value to preserve RT-PCR from avoidable usage and, importantly, to save time, which translated into a timely RT-PCR result availability in the COVID-19 area.

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Detection of enteroviruses in marine waters by direct RT-PCR and cell culture

Water Science & Technology ◽

10.2166/wst.1995.0635 ◽

1995 ◽

Vol 31 (5-6) ◽

pp. 323-328 ◽

Cited By ~ 8

Author(s):

K. A. Reynolds ◽

C. P. Gerba ◽

I. L. Pepper

Keyword(s):

Cell Culture ◽

Polymerase Chain Reaction Amplification ◽

Cost Effective ◽

The United States ◽

Water Runoff ◽

Rt Pcr ◽

Marine Waters ◽

Storm Water Runoff ◽

Routine Monitoring ◽

Reaction Amplification

Sewage outfalls and storm water runoff introduces pathogenic human enteric viruses into marine coastal waters, which may pose a potential public health risk. Although members of the enterovirus group have been suggested as possible indicators of sewage pollution in marine waters, the lack of rapid, sensitive and cost effective methods have prevented routine monitoring in the United States. This study compared traditional cell culture and direct RT-PCR (reverse transcriptase-polymerase chain reaction) amplification for detection of an enterovirus. Poliovirus could be recovered from 100 L of artificial seawater with an average efficiency of 77%, using adsorption and elution from electronegative filters. Viruses were eluted from the filters with 1.5% beef extract for viruses (BEV) adjusted to pH 9.5 and reconcentrated by organic flocculation to a volume of 30 mL. Substances which interfered with detection by RT-PCR were removed by treatment of the concentrates with sephadex and chelex resins. Direct RT-PCR could detect 2.5 and 0.025 PFU (plaque forming units) for single (25 cycles) and double PCR (2 × 25 cycles) in 10 μL of pure culture poliovirus samples, respectively. These methods are currently being applied to assess the occurrence of enteroviruses at marine bathing beaches influenced by sewage discharges.

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Investigations, actions and learning from an outbreak of SARS-CoV-2 infection among healthcare workers in the United Kingdom

Journal of Infection Prevention ◽

10.1177/1757177420976798 ◽

2020 ◽

pp. 175717742097679

Author(s):

Kordo Saeed ◽

Emanuela Pelosi ◽

Nitin Mahobia ◽

Nicola White ◽

Christopher Labdon ◽

...

Keyword(s):

Real Time ◽

Healthcare Workers ◽

Healthcare Facility ◽

Rt Pcr ◽

Serum Samples ◽

The United Kingdom ◽

Key Issues ◽

Current Infection ◽

Polymerase Chain ◽

A Current

Background: We report an outbreak of SARS coronavirus-2 (SARS-CoV-2) infection among healthcare workers (HCW) in an NHS elective healthcare facility. Methodology: A narrative chronological account of events after declaring an outbreak of SARS-CoV-2 among HCWs. As part of the investigations, HCWs were offered testing during the outbreak. These were: (1) screening by real-time reverse transcriptase polymerase chain reaction (RT- PCR) to detect a current infection; and (2) serum samples to determine seroprevalence. Results: Over 180 HCWs were tested by real-time RT-PCR for SARS-CoV-2 infection. The rate of infection was 15.2% (23.7% for clinical or directly patient-facing HCWs vs. 4.8% in non-clinical non-patient-facing HCWs). Of the infected HCWs, 57% were asymptomatic. Seroprevalence (SARS-CoV-2 IgG) among HCWs was 13%. It was challenging to establish an exact source for the outbreak. The importance of education, training, social distancing and infection prevention practices were emphasised. Additionally, avoidance of unnecessary transfer of patients and minimising cross-site working for staff and early escalation were highlighted. Establishing mass and regular screening for HCWs are also crucial to enabling the best care for patients while maintaining the wellbeing of staff. Conclusion: To our knowledge, this is the first UK outbreak report among HCWs and we hope to have highlighted some key issues and learnings that can be considered by other NHS staff and HCWs globally when dealing with such a task in future.

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The management of surgical patients in the emergency setting during COVID-19 pandemic: the WSES position paper

World Journal of Emergency Surgery ◽

10.1186/s13017-021-00349-0 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Belinda De Simone ◽

Elie Chouillard ◽

Massimo Sartelli ◽

Walter L. Biffl ◽

Salomone Di Saverio ◽

...

Keyword(s):

Systematic Review ◽

Emergency Surgery ◽

Healthcare Workers ◽

Mass Casualty ◽

Position Paper ◽

Surgical Patients ◽

Nasopharyngeal Swab ◽

Emergency Setting ◽

Open Approach ◽

Rt Pcr

Abstract Background Since the COVID-19 pandemic has occurred, nations showed their unpreparedness to deal with a mass casualty incident of this proportion and severity, which resulted in a tremendous number of deaths even among healthcare workers. The World Society of Emergency Surgery conceived this position paper with the purpose of providing evidence-based recommendations for the management of emergency surgical patients under COVID-19 pandemic for the safety of the patient and healthcare workers. Method A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) through the MEDLINE (PubMed), Embase and SCOPUS databases. Synthesis of evidence, statements and recommendations were developed in accordance with the GRADE methodology. Results Given the limitation of the evidence, the current document represents an effort to join selected high-quality articles and experts’ opinion. Conclusions The aim of this position paper is to provide an exhaustive guidelines to perform emergency surgery in a safe and protected environment for surgical patients and for healthcare workers under COVID-19 and to offer the best management of COVID-19 patients needing for an emergency surgical treatment. We recommend screening for COVID-19 infection at the emergency department all acute surgical patients who are waiting for hospital admission and urgent surgery. The screening work-up provides a RT-PCR nasopharyngeal swab test and a baseline (non-contrast) chest CT or a chest X-ray or a lungs US, depending on skills and availability. If the COVID-19 screening is not completed we recommend keeping the patient in isolation until RT-PCR swab test result is not available, and to manage him/she such as an overt COVID patient. The management of COVID-19 surgical patients is multidisciplinary. If an immediate surgical procedure is mandatory, whether laparoscopic or via open approach, we recommend doing every effort to protect the operating room staff for the safety of the patient.

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Implementing SARS-CoV-2 Rapid Antigen Testing in the Emergency Ward of a Swiss University Hospital: The INCREASE Study

Microorganisms ◽

10.3390/microorganisms9040798 ◽

2021 ◽

Vol 9 (4) ◽

pp. 798

Author(s):

Giorgia Caruana ◽

Antony Croxatto ◽

Eleftheria Kampouri ◽

Antonios Kritikos ◽

Onya Opota ◽

...

Keyword(s):

Immunoglobulin A ◽

University Hospital ◽

Lower Sensitivity ◽

Clinical Settings ◽

Rt Pcr ◽

Emergency Ward ◽

Viral Loads ◽

Asymptomatic Patients ◽

Asymptomatic Subjects ◽

Antigen Testing

Following the Swiss Federal Office of Public Health (FOPH) authorization of the rapid antigen test (RAT), we implemented the use of the RAT in the emergency ward of our university hospital for patients’ cohorting. RAT triaging in association with RT-PCR allowed us to promptly isolate positive patients and save resources. Among 532 patients, overall sensitivities were 48.3% for Exdia and 41.2% for Standard Q®, PanbioTM and BD Veritor™. All RATs exhibited specificity above 99%. Sensitivity increased to 74.6%, 66.2%, 66.2% and 64.8% for Exdia, Standard Q®, PanbioTM and BD Veritor™, respectively, for viral loads above 105 copies/mL, to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/mL and 100% for viral loads above 107 copies/mL. Sensitivity was significantly higher for patients with symptoms onset within four days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with the evolution of symptoms longer than four days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Among COVID-19 asymptomatic patients, sensitivity was 33%. All Immunoglobulin-A-positive patients resulted negative for RAT. The RAT might represent a useful resource in selected clinical settings as a complementary tool in RT-PCR for rapid patient triaging, but the lower sensitivity, especially in late presenters and COVID-19 asymptomatic subjects, must be taken into account.

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Eastern Cape Healthcare Workers Acquisition of SARS-CoV-2 (ECHAS): Cross-Sectional (Nested Cohort) Study Protocol

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18010323 ◽

2021 ◽

Vol 18 (1) ◽

pp. 323

Author(s):

Oladele Vincent Adeniyi ◽

David Stead ◽

Mandisa Singata-Madliki ◽

Joanne Batting ◽

Leo Hyera ◽

...

Keyword(s):

Cohort Study ◽

Infection Rate ◽

Healthcare Workers ◽

Health Facilities ◽

Control Measures ◽

Infection Prevention And Control ◽

Eastern Cape ◽

Rt Pcr ◽

Cross Sectional ◽

Increased Risk

Healthcare workers (HCWs) are at increased risk of infection by the virulent severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Though data exist on the positivity rate of the SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) test as well as COVID-19-related deaths amongst HCWs in South Africa, the overall infection rate remains underestimated by these indicators. It is also unclear whether the humoral immune response after SARS-CoV-2 infection offers durable protection against reinfection. This study will assess the SARS-CoV-2 seroprevalence amongst HCWs in the Eastern Cape (EC) and examine the longitudinal changes (rate of decay) in the antibody levels after infection in this cohort. Using a multi-stage cluster sampling of healthcare workers in selected health facilities in the EC, a cross-sectional study of 2250 participants will be recruited. In order to assess the community infection rate, 750 antenatal women in the same settings will be recruited. Relevant demographic and clinical characteristics will be obtained by a self-administered questionnaire. A chemiluminescent microparticle immunoassay (CMIA) will be used for the qualitative detection of IgG antibodies against SARS-CoV-2 nucleocapsid protein. A nested cohort study will be conducted by performing eight-weekly antibody assays (X2) from 201 participants who tested positive for both SARS-CoV-2 RT-PCR and serology. Logistic regression models will be fitted to identify the independent risk factors for SARS-CoV-2 infection. The cumulative SARS-CoV-2 infection rate and infection fatality rate among the frontline HCWs will be estimated. In addition, the study will highlight the overall effectiveness of infection prevention and control measures (IPC) per exposure sites/wards at the selected health facilities. Findings will inform the South African Department of Health’s policies on how to protect HCWs better as the country prepares for the second wave of the SARS-CoV pandemic.

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