Lessons Learned from In-Person Conferences in the Times of COVID-19.

Scientific societies and conference secretariats have recently resumed in-person meetings after a long pause owing to the COVID-19 pandemic. Some safety measures continue to be implemented at these in-person events to limit the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With increased numbers of waves of infection, caused by the emergence of SARS-CoV-2 variants, additional information is needed to ensure maximal safety at in-person events. The MEX-DART case study was conducted at the in-person Hep-DART 2021 conference, which was held in Los Cabos, Mexico, in December 2021. Many COVID-19 safety measures were implemented, and incidence of SARS-CoV-2 infection during the conference was tested onsite. In this study, we highlight the specific conditions and safety measures set in place at the conference. In addition to vaccination requirements, social distancing, and mask wearing, daily rapid testing was implemented for the duration of the conference. At the end of the 4-day meeting, none of the 166 delegates (and family members attending the conference) had tested antigen positive for SARS-CoV-2. Two delegates tested positive in the week after the conference; the timing of their positive test result suggests that they contracted the virus during their travels home or during postconference vacationing. We believe that this model can serve as a helpful template for organizing future in-person meetings in the era of COVID-19 and any other respiratory virus pandemics of the future. While the outcomes of this case study are encouraging, seasonal surges in respiratory virus infections such as SARS-CoV-2, RSV, and influenza virus incidence suggest that continued caution is warranted.

Lessons From the Field: Rapid Antigen Testing Is Efficient and Practical for Mitigation of Coronavirus Disease 2019 Outbreaks in Long-Term Care Facilities.

Background: Mitigation of coronavirus disease 2019 (COVID-19) outbreaks in long-term care facilities (LTCFs) is facilitated by rapid identification and isolation of infectious individuals to interrupt viral transmission. Immunochromatographic (IC) tests, or rapid antigen tests, have high sensitivity and specificity during the contagious period for COVID-19. Mathematical modeling predicts frequent IC surveillance will be more efficient than polymerase chain reaction (PCR)-based strategies, especially during community surges when reporting of PCR results can be delayed. However, there are few published field studies evaluating IC testing strategies in this long-term care setting. Methods: In fall and winter of 2020, the Marin Health and Human Services Department implemented thrice-weekly IC mass testing by nonlaboratory workers in outbreaks that occurred in 2 LTCFs, in addition to then-standard semiweekly PCR testing. The IC test performance was characterized using same-day PCR specimens as reference standard. Cumulative incidence and duration of transmission for the 2 IC intervention facility outbreaks were compared with 6 reference LTCFs that used weekly to semiweekly PCR alone during an outbreak response. Results: Of 123 same-day test pairs, IC test sensitivity and specificity were 75% (95% confidence interval [CI], 48%-93%) and 100% (95% CI, 97%-100%), respectively. The median duration of outbreak transmission was 19.5 days in the 2 intervention sites and 28 days in the reference facilities (P = .40). Cumulative incidence for the outbreaks among LTCF residents was 41% in the intervention facilities versus 52% in the reference facilities (P = .04, Fisher 2-sided exact). Conclusions: Thrice-weekly mass IC testing as used by nonlaboratory personnel can be highly practical and effective for COVID-19 outbreak mitigation in the LTCF setting.

Hesitancy to Undergo SARS-CoV-2 Rapid Antigen Testing in China: Nationwide Cross-sectional Study.

BACKGROUND: SARS-CoV-2 rapid antigen testing (RAT) could be a useful supplementary test to diagnose larger numbers of acute asymptomatic infections and alleviate the limitations of polymerase chain reaction testing. However, hesitancy to undergo SARS-CoV-2 RAT may compromise its implementation. OBJECTIVE: We aimed to understand the prevalence and correlates of hesitancy to undergo RAT among adults not infected with SARS-CoV-2 in mainland China. METHODS: A nationwide cross-sectional survey on hesitancy to undergo SARS-CoV-2 RAT was conducted among adults not infected with SARS-CoV-2 in mainland China between April 29, 2022, and May 10, 2022. Participants completed an online questionnaire that covered the following COVID-19-related factors: sociodemographic characteristics, experiences of COVID-19 restrictions and knowledge of COVID-19, and attitude toward COVID-19 and its screening. This study was a secondary analysis of data from the survey. We compared the characteristics of participants by hesitancy to undergo SARS-CoV-2 RAT. Thereafter, logistic regression with a sparse group minimax concave penalty was used to identify correlates of hesitancy to undergo RAT. RESULTS: We recruited 8856 individuals with diverse demographic, socioeconomic, and geographic characteristics in China. Eventually, 5388 participants (valid response rate of 60.84%; 52.32% [2819/5388] women; median age 32 years) were included in the analysis. Among the 5388 participants, 687 (12.75%) expressed hesitancy to undergo RAT and 4701 (87.25%) were willing to undergo RAT. Notably, those who were from the central region (adjusted odds ratio [aOR] 1.815, 95% CI 1.441-2.278) and those who received COVID-19 information from traditional media (aOR 1.544, 95% CI 1.279-1.863) were significantly more likely to report hesitancy to undergo RAT (both P<.001). However, those who were women (aOR 0.720, 95% CI 0.599-0.864), were older (aOR 0.982, 95% CI 0.969-0.995), had postgraduate education (aOR 0.612, 95% CI 0.435-0.858), had children (<6 years old) and elders (>60 years old) in the family (aOR 0.685, 95% CI 0.510-0.911), had better knowledge about COVID-19 (aOR 0.942, 95% CI 0.916-0.970), and had mental health disorders (aOR 0.795, 95% CI 0.646-0.975) were less likely to report hesitancy to undergo RAT. CONCLUSIONS: Hesitancy to undergo SARS-CoV-2 RAT was low among individuals who were not yet infected with SARS-CoV-2. Efforts should be made to improve the awareness and acceptance of RAT among men, younger adults, individuals with a lower education or salary, families without children and elders, and individuals who access COVID-19 information via traditional media. In a reopening world, our study could inform the development of contextualized mass screening strategies in general and the scale-up of RAT in particular, which remains an indispensable option in emergency preparedness.

Comparison between the Sofia SARS Antigen FIA Test and the PCR Test in Detection of SARS-CoV-2 Infection.

OBJECTIVE: The purpose of this study was to compare Quidel's rapid antigen test Sofia SARS antigen Fluorescent Immunoassay (FIA) (Sofia) with the real-time reverse transcription-polymerase chain reaction (rRT-PCR) test. METHODS: Two samples were taken from each test subject-1 for testing with the Sofia test and 1 for testing with the rRT-PCR test. In total, swabs were taken from 146 subjects who presented symptoms of infection (group 1) and 672 subjects who were tested regardless of symptoms (group 2). RESULTS: In group 1, the sensitivity of the antigen test was 90.0% and its specificity 97.5%. In group 2, however, the sensitivity of the antigen test was 81.4% and the specificity 98.9%. In addition to asymptomatic patients, false-negative results of rapid antigen tests also occurred in subjects with high threshold values (cycle threshold > 30). CONCLUSION: Our results show that the Sofia test meets the standards for diagnostic tests according to the criteria of the World Health Organization, as they show high sensitivity and specificity, and perhaps most importantly, a high negative predictive value (> 95%).

Say Yes! COVID Test: A Health Communication Campaign to Encourage Use of Rapid, At-Home Antigen Testing in Underserved and Historically Marginalized Communities.

This paper describes a robust health communication campaign that supported Say Yes! COVID Test, the first National Institutes of Health (NIH)-sponsored initiative promoting community-wide, at-home, rapid antigen testing for severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), the cause of the COVID-19 pandemic. The primary goals of the health communication campaign were to promote awareness of the program among local residents, facilitate test kit distribution, and encourage frequent test kit use. To plan and implement the campaign, the team applied principles of social marketing. The populations of focus were adult residents of selected communities in North Carolina (Greenville, Pitt County) and Tennessee (Chattanooga, Hamilton County), with an emphasis on underserved and historically marginalized populations. Following an accelerated planning phase, the campaign included digital, out-of-home, television, and radio advertising, in addition to public relations and organic social media. Collectively, this campaign coupled with our grassroots community engagement efforts facilitated the distribution of 66 035 test kits across both communities, or more than 1.6 million at-home tests. Facebook ads were the most successful in driving online test kit orders (7.9% conversion rate in Pitt County; 8.1% conversion rate in Chattanooga), although employing a variety of marketing channels enabled reach across multiple subpopulations. Market research data indicated high program awareness but low uptake in testing. Lessons learned from campaign planning and implementation can inform future public health initiatives, including selecting the appropriate marketing mix to facilitate awareness, and collaborating with community partners and local health departments to ensure successful program execution.

Accuracy of an antigen-detecting SARS-CoV-2 assay with self- and provider-collected specimens interpreted visually and with BD Veritor™ Plus analyzer.

Background: SARS-CoV-2 rapid antigen tests (RATs) are in high demand for reducing the spread of SARS-CoV-2. Reduced involvement from health care professionals (HCPs) for collection and interpretation could significantly foster the wide-spread implementation of RATs, but data evaluating RATs, when used by lay people, is limited. Objective: To valuate agreement between BD Veritor test results for self- and HCP-collected specimens, and visually- and analyzer-interpreted results. Methods: Individuals with onset of COVID-19 symptoms within five days of enrollment had three nasal swabs collected; one self-collected and the other two HCP-collected. One HCP-collected swab was stored for future testing while the order of the other two (self and HCP) was randomized before testing. with the BD Veritor System for Rapid Detection of SARS-CoV-2. Results were first assessed visually, followed by interpretation with the analyzer. Results: When self-collection was compared to HCP collection for SARS-CoV-2 detection, interpretation by analyzer resulted in positive percent agreement (PPA) of 94.7% (95% CI 82.7, 98.5) and negative percent agreement (NPA) of 99.0% (95% CI 97.5, 99.6). When visual interpretation was compared to analyzer-read results, collection by HCPs had a PPA of 97.4% (95% CI 86.5, 99.5) and NPA of 99.8% (95% CI 98.6, 100.0) while self-collection resulted in PPA of 94.9% (95% CI 83.1, 98.6) and NPA of 99.8% (95% CI 98.6, 100). Conclusions: Similar PPA and NPA were observed for self- and HCP-collected specimens as well as visually- and analyzer-interpreted tests. The equivalence in performance supports the use of expanded collection and testing methods.

Rapid Antigen Assays for SARS-CoV-2: Promise and Peril.

Though rapid antigen tests have historically problematic performance characteristics for the diagnosis of respiratory viral infections such as influenza, they have attained an unprecedented level of use in the context of the COVID-19 pandemic. Ease of use and scalability of rapid antigen tests has facilitated a democratization and scale of testing beyond anything reasonably achievable by traditional laboratory-based testing. In this chapter, we discuss the performance characteristics of rapid antigen testing for SARS-CoV-2 detection and their application to non-traditional uses beyond clinical diagnostic testing.

Comparison of Nasopharyngeal and Saliva Swab Nucleic Acid Amplification and Rapid Antigen Testing To Detect Omicron SARS-CoV-2 Variant of Concern: a Prospective Clinical Trial (OMICRON).

In November 2021, the World Health Organization declared the Omicron variant (B.1.1.519) a variant of concern. Since then, worries have been expressed regarding the ability of usual diagnostic tests to detect the Omicron variant. In addition, some recently published data suggested that the salivary reverse transcription (RT)-PCR might perform better than the current gold standard, nasopharyngeal (NP) RT-PCR. In this study, we aimed to compare the sensitivities of nasopharyngeal and saliva RT-PCR and assess the diagnostic performances of rapid antigen testing (RAT) in nasopharyngeal and saliva samples. We conducted a prospective clinical study among symptomatic health care professionals consulting the occupational health service of our hospital for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) screening and hospitalized patients in internal medicine/intensive care wards screened for SARS-CoV-2 with COVID-19-compatible symptoms. A composite outcome considering NP PCR and/or saliva PCR was used as a reference standard to define COVID-19 cases. A total of 475 paired NP/saliva specimens have been collected with a positivity rate of 40% (n = 192). NP and salivary RT-PCR exhibited sensitivities of 98% (95% CI, 94 to 99%) and 87% (95% CI, 81 to 91%), respectively, for outpatients (n = 453) and 94% (95% CI, 72 to 99%) and 69% (95% CI, 44 to 86%), respectively, for hospitalized patients (n = 22). Nasopharyngeal rapid antigen testing exhibited much lower diagnostic performances (sensitivity of 66% and 31% for outpatients and inpatients, respectively), while saliva RAT showed a sensitivity of less than 5% in both groups. Nasopharyngeal RT-PCR testing remains the gold standard for SARS-CoV-2 Omicron variant screening. Salivary RT-PCR can be used as an alternative in case of contraindication to perform NP sampling. The use of RAT should be limited to settings where access to molecular diagnostic methods is lacking. IMPORTANCE The Omicron variant of concern spread rapidly since it was first reported in November 2021 and currently accounts for the vast majority of new infections worldwide. Recent reports suggest that saliva sampling might outweigh nasopharyngeal sampling for the diagnosis of the Omicron variant. Nevertheless, data investigating the best diagnostic strategy specifically for the Omicron variant of concern remain scarce. This study fills this gap in current knowledge and elucidates the question of which strategy to use in which patient. It provides a new basis for further improving COVID-19 screening programs and managing patients suspected to have COVID-19.

High Sensitivity and NPV for BinaxNOW Rapid Antigen Test in Children at a Mass Testing Site during Prevalent Delta Variant Period.

SARS-CoV-2 continues to develop new, increasingly infectious variants including delta and omicron. We evaluated the efficacy of the Abbott BinaxNOW Rapid Antigen Test against Reverse Transcription PCR (RT-PCR) in 1,054 pediatric participants presenting to a high-volume Coronavirus Disease 2019 (COVID-19) testing site while the delta variant was predominant. Both tests utilized anterior nares swabs. Participants were grouped by COVID-19 exposure and symptom status. 5.2% of samples tested positive by RT-PCR for SARS-CoV-2. For all participants, sensitivity of the BinaxNOW was 92.7% (95% CI 82.4%-98.0%), and specificity was 98.0% (95% CI 97.0%-98.8%). For symptomatic participants, positive predictive value (PPV) was 72.7% (95% CI 54.5%-86.7%) and negative predictive value (NPV) was 99.2% (95% CI 98.2%-100%). Among asymptomatic participants, PPV was 71.4% (95% CI 53.7%-85.4%) and NPV was 99.7% (95% CI 99.0%-100%). Our reported sensitivity and NPV are higher than other pediatric studies, potentially because of higher viral load from the delta variant, but specificity and PPV are lower. IMPORTANCE The BinaxNOW rapid antigen COVID-19 test had a sensitivity of nearly 92% in both symptomatic and asymptomatic children when performed at a high-throughput setting during the more transmissible delta variant dominant period. The test may play an invaluable role in asymptomatic screening and keeping children safe in school.

Engaging nursing students in a COVID-19 Point-of-Care rapid screening clinic.

BACKGROUND: The COVID-19 pandemic has globally impacted nursing education, particularly clinical learning opportunities for undergraduate nursing students. PURPOSE: In this paper, we report on an educational activity wherein students participated in a COVID-19 Rapid Antigen Testing (RAT) clinic on a Canadian university campus. METHODS: Between February-April 2021, in the second term of a five-term accelerated program, nursing students (n = 60) participated in a nurse-led COVID-19 RAT clinic for students and staff living or working in congregate housing. Students participated in education activities which exposed nursing students to the full range of community health nursing roles in a pandemic. RESULTS: From clinical, research, policy, and public health, this educational activity acted as a microcosm of the critical roles that nurses employ in the health ecosystem. CONCLUSION: We offer lessons learned about implementing this activity, and how these lessons can be applied to routine and exceptional nursing curriculum.

Utility of SARS-CoV-2 rapid antigen testing for patient triage in the emergency department: A clinical implementation study in Melbourne, Australia.

Background: Early, rapid detection of SARS-CoV-2 is essential in healthcare settings in order to implement appropriate infection control precautions and rapidly assign patients to care pathways. Rapid testing methods, such as SARS-CoV-2 rapid antigen testing (RAT) may improve patient care, despite a lower sensitivity than real-time PCR (RT-PCR) testing. Methods: Patients presenting to an Emergency Department (ED) in Melbourne, Australia, were risk-stratified for their likelihood of active COVID-19 infection, and a non-randomised cohort of patients were tested by both Abbott Panbio™ COVID-19 Ag test (RAT) and SARS-CoV-2 RT-PCR. Patients with a positive RAT in the 'At or High Risk' COVID-19 group were moved immediately to a COVID-19 ward rather than waiting for a RT-PCR result. Clinical and laboratory data were assessed to determine test performance characteristics; and length of stay in the ED was compared for the different patient cohorts. Findings: Analysis of 1762 paired RAT/RT-PCR samples demonstrated an overall sensitivity of 75.5% (206/273; 95% CI: 69·9-80·4) for the Abbott Panbio™ COVID-12 Ag test, with specificity of 100% (1489/1489; 95% CI: 99·8-100). Sensitivity improved with increasing risk for COVID-19 infection, from 72·4% (95% CI: 52·8-87·3) in the 'No Risk' cohort to 100% (95% CI: 29·2-100) in the 'High Risk' group. Time in the ED for the 'At/High Risk' group decreased from 421 minutes (IQR: 281, 525) for those with a positive RAT result to 274 minutes (IQR:140, 425) for those with a negative RAT result, p = 0.02. Interpretation: The positive predictive value of a positive RAT in this setting was high, allowing more rapid instigation of COVID-19 care pathways and an improvement in patient flow within the ED. Funding: Royal Melbourne Hospital, Melbourne, Australia.

Large-Scale SARS-CoV-2 Antigen Testing With Real-World Specimens.

Real-world data are needed to establish SARS-CoV-2 rapid antigen testing (RAT) as an effective and reliable approach for SARS-CoV-2 screening. This study included 1,952,931 individuals who provided upper respiratory specimens during SARS-CoV-2 screening at CityMD urgent care locations in the New York metropolitan area from October 2020 to March 2021. Positive and negative results, as determined by the BD Veritor™ System for Rapid Detection of SARS-CoV-2 antigen (Veritor), were obtained for all individuals, with reflex reverse transcriptase-polymerase chain reaction (RT-PCR) testing performed on a case-by-case basis, per standard of care. Using verification bias adjustment, two alternative model assumptions were utilized for RAT results with missing reflex RT-PCR results. The worst antigen diagnostic performance estimates asserted that missing RT-PCR results would show a distribution similar to those RT-PCR results actually obtained, based on symptom category. The best antigen diagnostic performance estimates asserted that individuals without RT-PCR results had a clinical presentation consistent with RAT results, and, therefore, missing RT-PCR results would agree with RAT results. For patients with symptoms or high-risk exposure, 25.3% (n = 86,811/343,253) of RAT results were positive; vs. 3.4% (n = 53,046/1,559,733) positive for asymptomatic individuals without high-risk exposure. Reflex RT-PCR results were obtained from 46.3% (n = 158,836/343,253) and 13.8% (n = 215,708/1,559,733) of symptomatic and asymptomatic individuals, respectively. RT-PCR confirmed 94.4% (4,265/4,518) of positive and 90.6% (139,759/154,318) of negative RAT results in symptomatic individuals; and confirmed 83.4% (6,693/8,024) of positive and 95.3% (197,955/207,684) of negative RAT results in asymptomatic individuals. Applied assumptions for missing reflex RT-PCR results led to worst performance sensitivity estimates of 77.2 and 38.5% in the symptomatic and asymptomatic populations, respectively; assumptions for best performance estimates led to sensitivity values of 85.6 and 84.2%, respectively. Specificity values, regardless of assumptions or symptom category, ranged from 97.9-99.9%. At 10% SARS-CoV-2 prevalence, RAT positive predictive value was 86.9 and 99.0% for worst and best performance estimates across the total population, respectively; negative predictive values were >95% regardless of the applied assumption. Veritor test performance was consistent with that listed in the manufacturer instructions for use for symptomatic individuals. Real-world evidence should be gathered on RATs to support their efficacy as SARS-CoV-2 persists.

Evaluation of Five Commercial SARS-CoV-2 Antigen Tests in a Clinical Setting.

BACKGROUND: Point-of-care antigen tests (AgTs) for the detection of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) enable the rapid testing of infected individuals and are easy-to-use. However, there are few studies evaluating their clinical use. OBJECTIVE: The present study aimed to evaluate and compare the clinical performance characteristics of various commercial SARS-CoV-2 AgTs. DESIGN: The sensitivity of five AgTs, comprising four rapid antigen tests (RAT; AMP Rapid Test SARS-CoV-2 Ag, NADAL COVID-19 Antigen Rapid Test, CLINITEST Rapid COVID-19 Antigen Test, and Roche SARS-CoV-2 Rapid Antigen Test) and one sandwich chemiluminescence immunoassay (CLIA; LIAISON SARS-CoV-2 Assay), were evaluated in 300 nasopharyngeal (NP) swabs. Reverse transcriptase (RT) polymerase chain reaction (PCR) was used as a reference method. PARTICIPANTS: NP swabs were collected from patients admitted to hospital due to COVID-19. KEY RESULTS: Sensitivities of the AgTs ranged from 64.9 to 91.7% for samples with RT-PCR cycle threshold (Ct) values lower than 30 and were 100% for cycle threshold (Ct) values lower than 20. The highest sensitivity was observed for CLINITEST Rapid COVID-19 Antigen Test, and Roche SARS-CoV-2 rapid antigen test. Multivariate analysis using time from symptom onset and the Ct value for AgT sensitivity showed an inverse correlation. Further, the female sex was an independent factor of lower RAT sensitivity. CONCLUSIONS: Antigen tests from NP swab samples show high sensitivity in patients with a Ct value < 20. The best clinical sensitivity can be obtained using AgTs within the first 6 days after symptom onset.

From rapid antigen testing for COVID-19 to final outcome: An experience from industrial city of Ludhiana.

Context: The ongoing corona pandemic has created medical crises all over the world. An increased surge in the number of COVID-19 cases was observed in the month of August, September and October 2020. Punjab has around 10 Lakh migrant workers. Intensive rapid antigen testing was done during this surge among factory workers. With this background, the study aims to find out the positivity rate of rapid antigen testing and to find out the final outcome of the COVID positive cases in terms of morbidity. Materials and methods: Screening of factory workers working in various factories was done for COVID-19 by rapid antigen testing from 26th august to 31st October 2020. Those who tested positive were clinically examined, counseled, and followed up telephonically to get information regarding their course of illness. The collected information was entered in Microsoft excel sheet and analyzed using SPSS. Results: A total of 11045 factory workers were screened using the rapid antigen test. The mean age of subjects was 33.37 ± 10.97 years. The majority of them were males (88.3%) and migrants (who did not belong to Punjab) (97.3%). The majority of the subjects (97.3%) had no symptoms at the time of screening. COVID-19 positivity rate increased with age, was found to be higher in males (2.3%) as compared to females. Conclusion: The positivity rate was higher in asymptomatic males and local resident workers. Rapid antigen testing is an important public health measure to prevent the further spread of the disease during a pandemic due to its quick results and detection of asymptomatic patients.

Performance of the Sofia SARS-CoV-2 rapid antigen test as frontline test in a university hospital, Germany.

The rapid and reliable detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is of high importance for individual patient care and hospital infection prevention. We aimed to evaluate the performance of the Sofia SARS-CoV-2 antigen rapid diagnostic test (Ag-RDT) in comparison to real-time reverse-transcription polymerase chain reaction (RT-PCR). We conducted a prospective, monocentric cross-sectional study in an emergency department of a German university hospital from November 2020 to March 2021. We tested all samples using both Sofia SARS-CoV-2 Ag-RDT and real-time RT-PCR. A total of 7877 patients were included. Overall sensitivity of the Ag-RDT was 62.9% and specificity was 99.4%. Sensitivity varied across study months, whereas specificity remained high. Sensitivity increased to 94.2% in samples with a cycle threshold (Ct)-value ≤25. The Sofia Ag-RDT proved to be a rapid tool to detect samples with high viral loads (Ct-value ≤25) and might thus help to identify infectious patients.

Implementation and Accuracy of BinaxNOW Rapid Antigen COVID-19 Test in Asymptomatic and Symptomatic Populations in a High-Volume Self-Referred Testing Site.

Rapid antigen tests are simple to perform and provide results within 15 min. We describe our implementation and assess performance of the BinaxNOW COVID-19 Antigen Test (Abbott Laboratories) in 6,099 adults at a self-referred walk-up testing site. Participants were grouped by self-reported COVID-19 exposure and symptom status. Most (89%) were asymptomatic, of whom 17% reported potential exposure. Overall test sensitivity compared with reference laboratory reverse-transcription [RT] PCR testing was 81% (95% confidence interval [CI] 75%, 86%). It was higher in symptomatic (87%; 95% CI 80%, 91%) than asymptomatic (71%; 95% CI 61%, 80%) individuals. Sensitivity was 82% (95% CI 66%, 91%) for asymptomatic individuals with potential exposure and 64% (95% CI 51%, 76%) for those with no exposure. Specificity was greater than 99% for all groups. BinaxNOW has high accuracy among symptomatic individuals and is below the FDA threshold for emergency use authorization in asymptomatic individuals. Nonetheless, rapid antigen testing quickly identifies positive among those with symptoms and/or close contact exposure and could expedite isolation and treatment. IMPORTANCE The BinaxNOW rapid antigen COVID-19 test had a sensitivity of 87% in symptomatic and 71% asymptomatic individuals when performed by health care workers in a high-throughput setting. The performance may expedite isolation decisions or referrals for time-sensitive monoclonal antibody treatment in communities where timely COVID PCR tests are unavailable.

Factors that Influence the Reported Sensitivity of Rapid Antigen Testing for SARS-CoV-2.

Tests that detect the presence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigen in clinical specimens from the upper respiratory tract can provide a rapid means of coronavirus disease 2019 (COVID-19) diagnosis and help identify individuals who may be infectious and should isolate to prevent SARS-CoV-2 transmission. This systematic review assesses the diagnostic accuracy of SARS-CoV-2 antigen detection in COVID-19 symptomatic and asymptomatic individuals compared to quantitative reverse transcription polymerase chain reaction (RT-qPCR) and summarizes antigen test sensitivity using meta-regression. In total, 83 studies were included that compared SARS-CoV-2 rapid antigen-based lateral flow testing (RALFT) to RT-qPCR for SARS-CoV-2. Generally, the quality of the evaluated studies was inconsistent; nevertheless, the overall sensitivity for RALFT was determined to be 75.0% (95% confidence interval: 71.0-78.0). Additionally, RALFT sensitivity was found to be higher for symptomatic vs. asymptomatic individuals and was higher for a symptomatic population within 7 days from symptom onset compared to a population with extended days of symptoms. Viral load was found to be the most important factor for determining SARS-CoV-2 antigen test sensitivity. Other design factors, such as specimen storage and anatomical collection type, also affect the performance of RALFT. RALFT and RT-qPCR testing both achieve high sensitivity when compared to SARS-CoV-2 viral culture.

Optimal diagnostic test allocation strategy during the COVID-19 pandemic and beyond.

Timely diagnostic testing for active SARS-CoV-2 viral infections is key to controlling the spread of the virus and preventing severe disease. A central public health challenge is defining test allocation strategies with limited resources. In this paper, we provide a mathematical framework for defining an optimal strategy for allocating viral diagnostic tests. The framework accounts for imperfect test results, selective testing in certain high-risk patient populations, practical constraints in terms of budget and/or total number of available tests, and the purpose of testing. Our method is not only useful for detecting infections, but can also be used for long-time surveillance to detect new outbreaks. In our proposed approach, tests can be allocated across population strata defined by symptom severity and other patient characteristics, allowing the test allocation plan to prioritize higher risk patient populations. We illustrate our framework using historical data from the initial wave of the COVID-19 outbreak in New York City. We extend our proposed method to address the challenge of allocating two different types of diagnostic tests with different costs and accuracy, for example, the RT-PCR and the rapid antigen test (RAT), under budget constraints. We show how this latter framework can be useful to reopening of college campuses where university administrators are challenged with finite resources for community surveillance. We provide a R Shiny web application allowing users to explore test allocation strategies across a variety of pandemic scenarios. This work can serve as a useful tool for guiding public health decision-making at a community level and adapting testing plans to different stages of an epidemic. The conceptual framework has broader relevance beyond the current COVID-19 pandemic.

Sensitivity of Rapid Antigen Testing and RT-PCR Performed on Nasopharyngeal Swabs versus Saliva Samples in COVID-19 Hospitalized Patients: Results of a Prospective Comparative Trial (RESTART).

Saliva sampling could serve as an alternative non-invasive sample for SARS-CoV-2 diagnosis while rapid antigen tests (RATs) might help to mitigate the shortage of reagents sporadically encountered with RT-PCR. Thus, in the RESTART study we compared antigen and RT-PCR testing methods on nasopharyngeal (NP) swabs and salivary samples. We conducted a prospective observational study among COVID-19 hospitalized patients between 10 December 2020 and 1 February 2021. Paired saliva and NP samples were investigated by RT-PCR (Cobas 6800, Roche-Switzerland, Basel, Switzerland) and by two rapid antigen tests: One Step Immunoassay Exdia® COVID-19 Ag (Precision Biosensor, Daejeon, Korea) and Standard Q® COVID-19 Rapid Antigen Test (Roche-Switzerland). A total of 58 paired NP-saliva specimens were collected. A total of 32 of 58 (55%) patients were hospitalized in the intensive care unit, and the median duration of symptoms was 11 days (IQR 5-19). NP and salivary RT-PCR exhibited sensitivity of 98% and 69% respectively, whereas the specificity of these RT-PCRs assays was 100%. The NP RATs exhibited much lower diagnostic performance, with sensitivities of 35% and 41% for the Standard Q® and Exdia® assays, respectively, when a wet-swab approach was used (i.e., when the swab was diluted in the viral transport medium (VTM) before testing). The sensitivity of the dry-swab approach was slightly better (47%). These antigen tests exhibited very low sensitivity (4% and 8%) when applied to salivary swabs. Nasopharyngeal RT-PCR is the most accurate test for COVID-19 diagnosis in hospitalized patients. RT-PCR on salivary samples may be used when nasopharyngeal swabs are contraindicated. RATs are not appropriate for hospitalized patients.

Detection of SARS-CoV-2 at the point of care.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of COVID-19. Testing for SARS-CoV-2 infection is a critical element of the public health response to COVID-19. Point-of-care (POC) tests can drive patient management decisions for infectious diseases, including COVID-19. POC tests are available for the diagnosis of SARS-CoV-2 infections and include those that detect SARS-CoV-2 antigens as well as amplified RNA sequences. We provide a review of SARS-CoV-2 POC tests including their performance, settings for which they might be used, their impact and future directions. Further optimization and validation, new technologies as well as studies to determine clinical and epidemiological impact of SARS-CoV-2 POC tests are needed.