Evidence suggests that SARS-CoV-2 rapid antigen tests provide benefits for epidemic control - observations from Austrian schools

AbstractThe RT-qPCR in respiratory specimens is the gold standard for diagnosing acute COVID-19 infections. However, this test takes considerable time before test results become available, thereby delaying patients from being diagnosed, treated, and isolated immediately. Rapid antigen tests could overcome this problem. In the first study, clinical performances of five rapid antigen tests were compared to RT-qPCR in upper respiratory specimens from 40 patients with positive and 40 with negative RTq-PCR results. In the second study, the rapid antigen test with one of the best test characteristics (Romed) was evaluated in a large prospective collection of upper respiratory specimens from 900 different COVID-19-suspected patients (300 emergency room patients, 300 nursing home patients, and 300 health care workers). Test specificities ranged from 87.5 to 100.0%, and test sensitivities from 55.0 to 80.0%. The clinical specificity of the Romed test was 99.8% (95% CI 98.9–100). Overall clinical sensitivity in the study population was 73.3% (95% CI 67.9–78.2), whereas sensitivity in the different patient groups varied from 65.3 to 86.7%. Sensitivity was 83.0 to 86.7% in patients with short duration of symptoms. In a population with a COVID-19 prevalence of 1%, the negative predictive value in all patients was 99.7%. There is a large variability in diagnostic performance between rapid antigen tests. The Romed rapid antigen test showed a good clinical performance in patients with high viral loads (RT-qPCR cycle threshold ≤30), which makes this antigen test suitable for rapid identification of COVID-19-infected health care workers and patients.

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753. Performance Characteristics of Diagnostic Assays in Blastomycosis

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.943 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S424-S424

Author(s):

Timothy O’Dowd ◽

Jack McHugh ◽

Nancy Wengenack ◽

Elitza Theel ◽

Paschalis Vergidis

Keyword(s):

Granulomatous Inflammation ◽

Cross Reactivity ◽

Performance Characteristics ◽

Enzyme Linked Immunosorbent Assay ◽

Fungal Culture ◽

Noninvasive Test ◽

Serum Antigen ◽

Urine Antigen ◽

Antigen Tests ◽

Urine And Serum

Abstract Background Blastomycosis has historically been a difficult diagnosis to establish, often initially misdiagnosed as bacterial pneumonia. Serologic assays and polymerase chain reaction (PCR) tests are available, but their performance is not well defined. The objective of this study was to characterize their performance. Methods Subjects were identified via chart review of patients diagnosed with blastomycosis from 2005 to 2020. A definitive diagnosis was based on fungal culture, histopathology, or cytology. Performance characteristics of the Blastomyces antibody enzyme linked immunosorbent assay (ELISA), immunodiffusion (ID), complement fixation (CF), urine and serum antigen ELISAs, and PCR were evaluated in patients with confirmed blastomycosis. Data on patient demographics, location of disease, and mortality was also collected. Results We identified 193 patients with blastomycosis. The mean age was 51.8 years (range, 11-84) and 73.6% of patients were male. 42.5% resided in Minnesota, 18.1% in Wisconsin, and 12.9% in Iowa. Diagnosis was based on culture in 142 (73.2%) or histopathology/cytology in 67 (34.7%) patients. Granulomatous inflammation was present in 73.1% (38/52) while 21.2% (41/193) had evidence of extrapulmonary dissemination. The antibody, ID, and CF assays were positive in 43.5% (37/85), 35.1% (33/94) and 20.5% (8/39) of patients, respectively. Sensitivity of Blastomyces PCR was 40% (4/10) in sputum and 75% (21/28) in bronchoalveolar lavage (BAL) fluid. Blastomyces urine and serum antigen tests were positive in 68% (34/50) and 50% (9/18) of cases, respectively, while the urine antigen was positive in 63.6% (7/11) of disseminated cases. Patients had a positive Histoplasma urine antigen test in 54.1% (20/37) and Aspergillus galactomannan in BAL in 34.8% (8/23) of cases. Serum beta-D-glucan test was positive in 16.7% (2/12). 90-day mortality was 21/193 (10.9%) and median time from diagnosis to death was 18 days. Conclusion In this cohort, Blastomyces urine antigen was the most sensitive noninvasive test, with similar performance in pulmonary and disseminated disease. However, its utility is limited by poor specificity due to cross-reactivity. Blastomyces PCR from BAL fluid demonstrated the highest sensitivity. Blastomyces antibody, ID, and CF had poor sensitivity. Disclosures All Authors: No reported disclosures

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Need for Confirmatory Neutralization Tests for Hepatitis B Surface Antigen Tests in Populations with Intermediate Prevalence

Laboratory Medicine ◽

10.1093/labmed/lmab006 ◽

2021 ◽

Author(s):

Min Young Lee ◽

So Young Kang ◽

Woo In Lee ◽

Myeong Hee Kim

Keyword(s):

Hepatitis B ◽

Surface Antigen ◽

Neutralization Test ◽

Hepatitis B Surface Antigen ◽

False Negative ◽

Confirmatory Test ◽

Negative Group ◽

Positive Group ◽

Test Kit ◽

Antigen Tests

Abstract Objective Hepatitis B surface antigen (HBsAg) is known as the hallmark of hepatitis B virus (HBV) infection. This study aimed to determine whether an HBsAg neutralization test is necessary to accurately interpret HBsAg test results. Methods Initially reactive HBsAg specimens from a 5-year period, with cutoff index values between 1.0 and 2.0, were subjected to neutralization confirmatory testing using an Elecsys HBsAg Confirmatory test kit (Roche Diagnostics GmbH. Mannheim, Germany). Results The neutralization test showed 46.1% positive (confirmed positive group) and 53.9% negative (confirmed negative group) results from the total specimens. Among the confirmed negative group, 79.5% of patients were confirmed to be negative for the current infection, whereas 4 patients in the chronic hepatitis B subgroup showed a neutralization percentage close to 40%. More than half of patients in the confirmed positive group were considered to be in the hepatitis B e antigen-negative inactive HBsAg carrier phase. Conclusion In populations with intermediate HBV prevalence, a neutralization test is necessary to confirm an HBsAg result and reduce the false positive and false negative rates of initial HBsAg tests.

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Effectiveness of Epidemic Preventive Policies and Hospital Strategies in Combating COVID-19 Outbreak in Taiwan

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18073456 ◽

2021 ◽

Vol 18 (7) ◽

pp. 3456

Author(s):

Ting Wan Tan ◽

Han Ling Tan ◽

Man Na Chang ◽

Wen Shu Lin ◽

Chih Ming Chang

Keyword(s):

Mortality Rate ◽

Incidence Rate ◽

Risk Ratio ◽

Early Stage ◽

Control Measures ◽

Polymerase Chain Reaction Test ◽

Effective Control ◽

Nasopharyngeal Swab ◽

Preventive Strategies ◽

Epidemic Control

(1) Background: The implementation of effective control measures in a timely fashion is crucial to control the epidemic outbreak of COVID-19. In this study, we aimed to analyze the control measures implemented during the COVID-19 outbreak, as well as evaluating the responses and outcomes at different phases for epidemic control in Taiwan. (2) Methods: This case study reviewed responses to COVID-19 and the effectiveness of a range of control measures implemented for epidemic control in Taiwan and assessed all laboratory-confirmed cases between 11 January until 20 December 2020, inclusive of these dates. The confirmation of COVID-19 infection was defined as the positive result of a reverse-transcriptase–polymerase-chain-reaction test taken from a nasopharyngeal swab. Test results were reported by the Taiwan Centers for Disease Control. The incidence rate, mortality rate, and testing rate were compiled, and the risk ratio was provided to gain insights into the effectiveness of prevention measures. (3) Results and Discussion: This study presents retrospective data on the COVID-19 incidence rate in Taiwan, combined with the vital preventive control measures, in a timeline of the early stage of the epidemic that occurred in Taiwan. The implementation of multiple strategy control measures and the assistance of technologies to control the COVID-19 epidemic in Taiwan led to a relatively slower trend in the outbreak compared to the neighboring countries. In Taiwan, 766 confirmed patients were included, comprised of 88.1% imported cases and 7.2% local transmission cases, within the studied period. The incidence rate of COVID-19 in Taiwan during the studied period was 32 per million people, with a mortality rate of 0.3 per million people. Our analysis showed a significantly raised incidence risk ratio in the countries of interest in comparison to Taiwan during the study period; in the range of 1.9 to 947.5. The outbreak was brought under control through epidemic policies and hospital strategies implemented by the Taiwan Government. (4) Conclusion: Taiwan’s preventive strategies resulted in a drastically lower risk for Taiwan nationals of contracting COVID-19 when new pharmaceutical drug or vaccines were not yet available. The preventive strategies employed by Taiwan could serve as a guide and reference for future epidemic control strategies.

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