Correlation of patient symptoms with SARS-CoV-2 Omicron variant viral loads in nasopharyngeal and saliva samples and their influence on the performance of rapid antigen testing.

Evaluating SARS-CoV-2 viral loads in nasopharyngeal (NP) and saliva samples, factors affecting viral loads, and the performance of rapid antigen testing (RAT) have not been comprehensively conducted during SARS-CoV-2 Omicron epidemic. This prospective study included outpatients enrolled during Omicron variant period in Japan. Paired NP swab and saliva samples were collected to measure viral loads by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The correlation between viral loads and clinical symptoms was examined. The performance of an immunochromatography-based RAT kit was also assessed. A total of 153 patients tested within 3 days of symptom onset were included. The mean viral load was 5.60 log10 copies/test and 3.65 log10 copies/test in NP and saliva samples, respectively, resulting in a significant difference (P < 0.0001). Fever over 37°C (axillary temperature) and total number of symptoms other than fever were identified as independent factors positively correlated with the viral loads in both NP and saliva samples. RAT sensitivity using NP and saliva samples was 92% and 68%, respectively, using positive RT-qPCR results as the reference. The sensitivity of RAT using NP and saliva samples was significantly higher in patients with fever ≥37°C and/or at least one symptom than in those with fever <37°C and/or no symptoms (97% vs 83% in NP swabs; 80% vs 50% in saliva). Distinct symptoms, including fever ≥37°C, may reflect high Omicron variant viral loads. Rapid antigen testing, not only using nasopharyngeal swabs but also using saliva, would be useful for COVID-19 diagnosis as point-of-care testing, particularly for symptomatic patients. IMPORTANCE: We examined nasopharyngeal and salivary viral loads using samples collected from outpatients with SARS-CoV-2 infection during the Omicron epidemic in Japan and explored the outpatient factors correlated with viral loads. In addition, we evaluated the performance of an authorized rapid antigen testing (RAT) kit using nasopharyngeal and saliva samples with RT-PCR testing as the reference. Intriguingly, a correlation between fever and other symptoms and SARS-CoV-2 viral loads in nasopharyngeal and saliva samples was observed based on one COVID-19 outpatient visit. RAT sensitivity was influenced by viral loads. Nevertheless, nasopharyngeal RAT is considered useful for SARS-CoV-2 point-of-care diagnosis. In patients with distinct symptoms, including high-grade fever, salivary RAT could be a practical diagnostic tool because of the higher estimated viral loads. After the Omicron epidemic, outpatients with mild COVID-19 have become the main focus of diagnosis and treatment. Our study provides valuable information regarding the point-of-care diagnosis of these patients.

Assessment of DNA/RNA Defend Pro: An Inactivating Sample Collection Buffer for Enhanced Stability, Extraction-Free PCR, and Rapid Antigen Testing of Nasopharyngeal Swab Samples.

This study comprehensively evaluated the DNA/RNA Defend Pro (DRDP) sample collection buffer, designed to inactivate and stabilize patient samples. The primary objectives were to assess DRDP's efficacy in ensuring sample stability, facilitating extraction-free polymerase chain reaction (PCR), and ensuring compatibility with rapid antigen testing (RAT). Ninety-five diagnostic nasopharyngeal swab samples tested for influenza virus (influenza A), respiratory syncytial virus (RSV A), and/or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were 10-fold diluted with DRDP and anonymized. Initial characterization and retesting of these samples using cobas Liat confirmed 88 samples as positive, validating the presence of viral targets. Results from rapid antigen testing showed lower sensitivity compared to nucleic acid amplification testing (NAAT) but maintained perfect specificity, with 40 out of 88 positive samples by cobas Liat also testing positive for RAT. Direct RT-qPCR of DRDP-diluted samples demonstrated robust compatibility, with 72 out of 88 samples positive for cobas Liat also testing positive by direct RT-qPCR. Non-concordant results could be explained by the 200-fold lower input of extraction-free NAAT. Stability testing involved incubating 31 positive samples at 4 °C, 20 °C, and 37 °C for 7 days, with extraction-free NAAT. DRDP guaranteed viral RNA stability at all temperatures for influenza A, SARS-CoV-2, and RSV A, showing stability up to 7 days at 4 °C. In conclusion, DRDP is an effective stabilizing medium compatible with direct RT-qPCR and rapid antigen testing and shows great potential for optimizing diagnostic processes, particularly in resource-limited or time-sensitive scenarios.

Assessing the performance of LumiraDx™ SARS-CoV-2 Ag test in detecting Omicron lineages: 2022-2023 study.

Background: The introduction of rapid antigen tests revolutionized the approach to SARS-CoV-2 diagnosis, offering prompt and accurate results with high sensitivity and specificity. Although it is more cost- and time-saving than the gold standard, real-time polymerase chain reaction (RT-PCR), the efficacy in general population screening in both hospital- and community-based settings remains unknown. Moreover, rapid antigen testing is limited by qualitative results. This study aims to evaluate the diagnostic reliability of the LumiraDx™ rapid antigen test during the Omicron era and to investigate its quantitative (analogue-to-digital converter (ADC)) results in comparison with RT-PCR Ct values. Methods: This prospective study included all adult patients with mild-to-moderate SARS-CoV-2 symptoms who were not hospitalised and did not require oxygen supplementation, consented to participate, and attended the Infectious and Tropical Diseases Unit of Padua University Hospital from July 14th, 2022 to January 3rd, 2023. The patients underwent two different tests simultaneously: a nasal LumiraDx™ swab and a real-time RT-PCR assay performed on a nasopharyngeal swab. Sampling was repeated several times for a subset of subjects. Results: We enrolled 266 consecutive participants and collected 601 pairs of LumiraDx™ and RT-PCR samples. The most prevalent variant was BA.4/BA.5 Omicron (60.2 %). The sensitivity and specificity of LumiraDx™ test when compared to real-time RT-PCR results as the reference standard were 93.1 % and 79.75 %, respectively. No significant differences in diagnostic reliability were found based on the available characteristics, age, sex, symptom status, or COVID-19 variant, except for the days from symptom onset. According to the multilevel logistic regression analysis, the only independent variable significantly associated with test concordance was the Ct value (adjusted odds ratio (OR) = 0.56, p < 0.001). Significant differences in quantitative ADC values were found between false negative (FN) versus true negative (TN), and false positive (FP) and true positive (TP) tests. Conclusions: This study showed that LumiraDx™ test is reliable for SARS-CoV-2 diagnosis in patients with mild-to-moderate SARS-CoV-2 symptoms. This finding confirms the efficacy of rapid antigen tests in monitoring vulnerable individuals during the current post-vaccination era. When compared with the RT-PCR, LumiraDx™ test effectively quantitatively distinguishes between FN and TN cases, as well as FP and true TP tests, despite inaccuracies in qualitative results.

Real-world utilisation of SARS-CoV-2 rapid antigen testing to enable face-to-face learning in Australian schools, an ecological study.

OBJECTIVE: The objective of this study was to describe the use of SARS-CoV-2 rapid antigen testing of COVID-19 contacts in New South Wales schools to determine return to in-person school attendance instead of home quarantine, between 6 November and 21 December 2021. METHODS: COVID-19 school contacts were required to quarantine for two weeks postexposure to the case. Students who opted into daily rapid antigen testing logged their results in a database, prior to school attendance, and obtained SARS-CoV-2 nucleic amplification acid testing on day 12-16. Secondary attack rates (SARs) in schools utilising rapid antigen testing (Test-to-Stay schools) and those not utilising rapid antigen testing (non-Test-to-Stay school) were calculated. RESULTS: We identified 9,887 people in 293 schools who reported performing at least one rapid antigen test (RAT). The SAR in RAT schools was 3.4% (95% confidence interval: 2.7-4.1) and non-RAT schools was 2.8% (95% confidence interval: 2.4-3.3). A total of 30,535 school days were preserved through this program. CONCLUSIONS: The use of RATs preserved in-person learning without a significant increase to SAR. IMPLICATION FOR PUBLIC HEALTH: Disruptions in face-to-face learning have long-term detrimental impacts on children and adolescents. Rapid antigen testing has been shown to be beneficial to maintain face-to-face learning in Australian schools and may be a useful method to safeguard from school disruptions in future pandemics.

Development and application of a high-sensitivity immunochromatographic test strip for detecting pseudorabies virus.

Introduction: Pseudorabies (PR) is a multi-animal comorbid disease caused by pseudorabies virus (PRV), which are naturally found in pigs. At the end of 2011, the emergence of PRV variant strains in many provinces in China had caused huge economic losses to pig farms. Rapid detection diagnosis of pigs infected with the PRV variant helps prevent outbreaks of PR. The immunochromatography test strip with colloidal gold nanoparticles is often used in clinical testing due to its low cost and high throughput. Methods: This study was designed to produce monoclonal antibodies targeting PRV through immunization of mice using the eukaryotic system to express the gE glycoprotein. Subsequently, paired monoclonal antibodies were screened based on their sensitivity and specificity for use in the preparation of test strips. Results and discussion: The strip prepared in this study was highly specific, only PRV was detected, and there was no cross-reactivity with glycoprotein gB, glycoprotein gC, glycoprotein gD, and glycoprotein gE of herpes simplex virus and varicellazoster virus, porcine epidemic diarrhea virus, Senecavirus A, classical swine fever virus, porcine reproductive and respiratory syndrome virus, and porcine parvovirus. Moreover, it demonstrated high sensitivity with a detection limit of 1.336 × 103 copies/µL (the number of viral genome copies per microliter); the coincidence rate with the RT-PCR detection method was 96.4%. The strip developed by our laboratory provides an effective method for monitoring PRV infection and controlling of PR vaccine quality.

The blood routine test holds screening values for influenza A in 2023: a retrospective study.

Background: Influenza A is the most common viral pathogen isolated from pediatric clinics during influenza seasons. Some young patients with influenza manifest rapid progression with high fever and severe sequelae, such as pneumonia and meningitis. Therefore, early diagnosis and prompt treatment are highly important. Specific diagnostic tests currently include antigen detection, antibody detection, nucleic acid test and virus isolation. Rapid antigen testing is the most commonly adopted method in the outpatient setting, but false negative results are frequently observed, which causes delayed treatment and severe outcome. Routine blood test is the most commonly used detection for the outpatients. Incorporating specific blood cell counts into rapid antigen test may overcome some technical issues and enable accurate early diagnosis. Methods: We enrolled 537 children with influenza-like symptoms like fever or respiratory symptoms from pediatric outpatients and 110 children without infectious diseases for control. Routine blood tests detected by a routine analyzer and influenza A virus antigen detection were performed in the patients. Significant blood routine parameters between groups were examined by statistical tests. Parameters in routine blood test were assessed by the receiver operating characteristic curve to find the screening indicators of influenza A. Multivariate logistic regression were used to establish the optimal combinations of blood routine parameters in our screening model. Results: Two subgroups were set according to age: ≤6 years old group and >6 years old group. In each group, patients were further divided into three subgroups: the influenza A-positive-result group (A+ group) (n=259), influenza A-negative-result group (A- group) (n=277) and healthy control group (H group) (n=110). Most routine blood parameters showed significant differences among the three subgroups in each age group. Notably, lymphocyte (LYM) number, platelet (PLT) number, lymphocyte-to-monocyte ratio (LMR) and LYM multiplied by PLT (LYM*PLT) exhibited extremely significant differences. Using A- group as a reference based on the area under the curve (AUC), both age groups had a similar trend. For A- group, the optimal cutoff value of LYM*PLT was 221.6, the AUC, the sensitivity and specificity were 0.6830, 55.71% and 76.92% in the ≤6 years old group. Meanwhile, the cutoff value of LYM*PLT was 196.7, and the AUC, the sensitivity and specificity were 0.6448, 53.97% and 70.81%, respectively in the >6 years old group. Screening model based on multivariate logistic regression model revealed that LYM*PLT was the optimal parameter combinations in ≤6 years old group (AUC =0.7202), while LYM and PLT were the optimal parameter combinations in >6 years old group (AUC =0.6760). Conclusions: Several blood routine parameters in children with influenza A demonstrate differential levels in both age subgroups. The LYM*PLT exhibits the potential screening value of influenza infection.

Protecting mass-gathering events in a pandemic with testing tracks and transparent information: an experimental study with festival guests.

Objective. To enable future open-air festivals during a pandemic, model festivals tested restricted access and behavioural rules to prevent SARS-CoV-2 transmissions. However, the uptake of health-protective measures depends on informed acceptance, meaning people are more likely to follow measures if they understand their effectiveness and related disease risks. Design and main outcome measures. With a series of online surveys, we studied risk perceptions of 6,500 festival guests and the association of perceived effectiveness of protective behaviours with reported compliance. In a scenario-based online experiment (N = 1,958) among festival guests, we tested the effect of informing transparently about the risk-reducing potential of protective measures at festivals on the intention to attend hypothetical events. Results. We found that guests tended to overestimate infection risks while still perceiving them as low. Self-reported mask wearing and distancing at and around the festivals could not be associated with the understanding of the measures' effectiveness. However, in addition to protective measures themselves, providing transparent information about their absolute risk-reducing effect increased intentions to attend festivals that employ varying protective measures. Conclusion. Our findings suggest that the acceptance of protected festivals can be influenced by transparent information about the effectiveness of protective measures. This calls for further research on evidence-based public health communications to improve their impact.

Knowledge and willingness toward SARS-CoV-2 rapid antigen testing among older adults in China: a nationwide cross-sectional study.

BACKGROUND AND AIMS: The end of the zero-COVID-19 policy placed a large number of older adults in China at increased risk of COVID-19 infection. SARS-CoV-2 rapid antigen testing (RAT) is a promising tool for scaling up testing and ensuring that patient management and public health measures can be implemented without delay. We aimed to understand the knowledge and willingness of RAT, and its correlates among older adults in China. METHODS: A nationwide cross-sectional survey on knowledge and willingness about RAT among older adults in China was conducted between January 14 and 28, 2023, shortly after the end of the zero-COVID-19 policy. An online questionnaire was used to collect information on sociodemographic characteristics, health characteristics, sources to access RAT information, and attitudes toward COVID-19 and its RAT. Logistic regression was used to assess correlates of knowledge of RAT and willingness to take RAT among older adults. RESULTS: A total of 1030 older adults (494 women and 536 men, mean age 68.7 ± 7.0 years) were recruited. 49.4% of the participants had a high level of RAT knowledge. After adjusting for sociodemographic characteristics, chronic diseases (0.70, 0.49-0.99), learning RAT from new media (5.46, 3.48-8.68) and traditional media (3.35, 2.13-5.34), and perceiving RAT as convenient (4.03, 2.80-5.85) were associated with levels of RAT knowledge. 53.3% of the participants were willing to take RAT. After adjusting for sociodemographic characteristics, learning RAT from new media (8.46, 5.26-14.0) and traditional media (1.63, 1.04-2.55), perceiving RAT as convenient (2.97, 2.10-4.22), and worrying about (re)infection with COVID-19 (2.12, 1.55-2.92) were associated with willingness to take RAT. CONCLUSION: The levels of RAT knowledge and willingness to take RAT among older adults in China may hinder the scale-up of RAT. Health education about RAT should be strengthened among older adults. Special efforts should be made to integrate traditional and new media to promote RAT among older adults, specifically, for virus susceptibility and the convenience of RAT. Given the reopening of society, our study could inform our response to future novel infectious diseases and aid in the timely scale-up of RAT.

Comparison of Manual versus Automated SARS-CoV-2 Rapid Antigen Testing in Asymptomatic Individuals.

The SARS-CoV-2 pandemic has infected more than 770 M people and killed more than 6.9 M persons worldwide. In the USA, as of August 2023, it has infected more than 103 M people while causing more than 1.1 M deaths. During a pandemic, it is necessary to rapidly identify those individuals infected with the virus so that disease transmission can be stopped. We examined the sensitivity of the Quidel Rapid Antigen test on the manual Sofia 2 platform and the Beckman-Coulter antigen test on the automated DxI-800 system for use in screening asymptomatic individuals at the University of Arizona from March through May 2021. A total of 378 asymptomatic subjects along with 176 validation sets of samples in 23 independent experiments were assessed in side-by-side antigen testing using both assays. Nasal swabs and saliva were used as viral sources. Manual testing (Quidel) was compared with automated testing (Beckman) methods for cost and efficiency. Limit dilution of viral antigen spiked samples was performed to determine sensitivity to antigen load by the tests. The results between the two tests were found to be concordant. Both tests were comparable in terms of detecting low numbers of positive subjects in the asymptomatic population. A concordance of 98% was observed between the two tests. Experiments also demonstrated that saliva specimens were an acceptable viral source and produced comparable results for each test. Overall, the two methods were interchangeable.

Equitable access to COVID-19 diagnostics: factors associated with the uptake of rapid antigen testing in Victoria, Australia, January - February 2022.

BACKGROUND: Accessible and accurate diagnostics are critical to control communicable diseases. Uptake of COVID-19 rapid antigen (RA) testing requires physical and financial access to tests, knowledge about usage, motivation, and ability to report results. We sought to understand patterns of and factors associated with RA test uptake in Victoria during a period of high caseload, RA test promotion, and difficulty accessing RA and PCR testing. We hypothesise RA test uptake is indicated by the ratio of cases diagnosed by RA test (probable) to those diagnosed using PCR (confirmed) (p:c). METHODS: Analysing case records, trends in p:c were assessed, between regions, sex, age groups, socio-economic strata and cultural diversity. Logistic regression assessed associations between case classification, and median age, postcode-level socio-economic disadvantage, and proportion overseas-born. RESULTS: We included 591,789 cases. Mean p:c was lower in socio-economically disadvantaged areas (decile 1 + 2: 0.90 vs. decile 9 + 10: 1.10), and in postcodes where the overseas-born population was above the Victorian average (0.83 vs. 1.05). Conversely, p:c was higher in younger age groups; with no difference between sexes overall. In metropolitan Melbourne, odds of RA test usage increased as socio-economic disadvantage decreased (decile 9 + 10, aOR 1.40, 95%CI 1.37-1.43, vs. decile 1 + 2; p < .001), decreased for cases from areas with a higher overseas-born population (aOR 0.85, 0.83-0.86, p < .001), and with older age. CONCLUSIONS: Reduced uptake of RA tests in Victoria is associated with socio-economic disadvantage, cultural diversity, and older age. Equitable access to COVID-19 diagnostics requires elimination of financial barriers, and greater engagement with culturally diverse and older groups. Inequitable RA test uptake may lead to case under-ascertainment, affecting resource allocation, effective control strategy development, in turn impacting COVID-19 morbidity and mortality, and could indicate relative engagement with response initiatives.

The Implementation Experience of COVID-19 Rapid Antigen Testing in a Large-Scale Construction Project in Victoria, Australia.

The coronavirus (COVID-19) pandemic has caused major disruptions to industries and workplaces. Rapid Antigen Tests (RATs) for COVID-19, which allow individuals to self-administer tests and receive timely results without laboratory testing, provide the opportunity for surveillance testing of asymptomatic individuals in non-medical settings. However, the literature offers few lessons regarding how to create enabling conditions for effective and sustainable implementation in a workplace setting. Guided by the RE-AIM framework, we assessed factors associated with the adoption, implementation, and maintenance of mandatory RAT in a large-scale construction project in Victoria, Australia. We used a mixed methods approach involving site observation, worker surveys (n = 30), and interviews with 51 site workers and managers to understand the implementation experience. Factors which facilitated adoption included easy, non-invasive testing procedure; sense of workplace safety; and strong backing by management and acceptance by workers that RATs helped limit COVID-19-related lost days of work. Gaps in knowledge and adherence to testing protocols, logistical challenges (test kit supply, observation of test results), and low appetite for long-term, mandatory testing emerged as challenges for effective implementation and sustainability. As RAT becomes normalized in a range of workplace settings, strategies will be required to support the sustainability of implementation, including longer-term acceptability of surveillance testing and adherence to testing protocols. Supplementary Information: The online version contains supplementary material available at 10.1007/s43477-023-00085-4.

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.

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.

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.

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%).

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.

Point-of-care detection of SARS-CoV-2 antigen among symptomatic vs. asymptomatic persons: Testing for COVID-19 vs. infectivity.

Background: Management of the coronavirus disease 2019 (COVID-19) pandemic caused by a novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) requires rapid and simple methods to detect COVID-19 patients and identify potential infectors. This study aimed to evaluate the utility of a point-of-care (PoC) rapid antigen diagnostic test (Ag-RDT) in these settings. Patients and methods: Individuals who consecutively presented for SARS-CoV-2 testing at a tertiary care center in Buenos Aires, Argentina, underwent PoC Ag-RDT testing and real-time RT-PCR (qRT-PCR) on the same day during June 2021. Results: Of 584 included subjects, 108 (18.5%) were symptomatic for COVID-19 while the remaining presented for miscellaneous reasons unrelated to possible or confirmed contact with a SARS-CoV-2-infected individual. A positive Ag-RDT result was obtained in 26 (24.1%) symptomatic and 7 (1.5%) asymptomatic persons (p < 0.001), which was concordant with qRT-PCR in 105/108 [97.2%, Cohen's kappa coefficient (κ) = 0.927] symptomatic and 467/476 (98.1% κ = 0.563) asymptomatic participants, with a positive percentage agreement (PPA; 95% confidence interval) of 89.7% (71.5-97.3%) and 42.9% (18.8-70.4%), respectively. None of the 11 false-negative diagnoses showed a Ct-value ≤20. Considering only failures with a Ct-value below 31 as hypothetical infectivity threshold of 105 SARS-CoV-2 RNA copies/mL, concordance was observed in 98.1% (κ = 0.746) in the asymptomatic population, accounting for a PPA of 66.7% (30.9-91%). Conclusions: PoC Ag-RDT accurately detected active SARS-CoV-2 infection and showed acceptable diagnostic performance in asymptomatic persons potentially spreading infectious virus. Ag-RDT may therefore be useful to slow down or stop transmission by enabling adequate decisions on isolation at a public health level.

Diagnostic accuracy of SARS-CoV-2 Panbio™ rapid antigen diagnostic tests in a 4,440-case clinical follow-up.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Rapid Antigen Detection Testing (RADT) has been subjected to several evaluations in reference to diagnostic accuracy, ranging from small scale up to large population studies including nation-wide community-based studies. All confirmed the diagnostic accuracy of the tests which were strongly dependent upon the infection's population prevalence. In our retrospective study, parallel SARS-CoV-2 Panbio™ RADT assay, including real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) tests, were aimed to evaluate diagnostic performance regarding the rapid antigen diagnostic testing. Out of 4,440 paired tests, 609 samples tested positive using RT-qPCR, resulting in a prevalence of 13.7%. Panbio detected 251 (5.7%) positive tested samples. Overall sensitivity was 41.2% (95% CI 37.4-45.2%) and overall specificity was 99.7% (95% CI 99.4-99.8%). Positive predictive value (PPV) was 95.1% (95% CI 91.8-97.1%) and the negative predictive value (NPV) was 91.4% (95% CI 90.5-92.2%). RADT sensitivity increased with stratification in reference to the results according to PCR Cycle threshold (Ct) and presence of the symptoms considerably influenced PPV and NPV. Sensitivity in the group of Ct values ≤ 20 was 91.2%, 68.6% within the Ct range of 20-25, 47.9% in the group of Ct values between 25 and 30, and 12.6% in the group of Ct values between 30 and 35. A follow-up of the positive cases aligned with RT-qPCR testing and comparison of the general population enrolled in the testing in which the fatal cases occurred enabled us to estimate real clinical diagnostic performance regarding the SARS-CoV-2 Panbio RADT. Based upon our results, we recommend the SARS-CoV-2 Panbio RADT tests be carried out as the primary test, without parallel PCR testing, only among high population prevalence rates of the infection and to be used for symptomatic individuals with average or low severe disease developmental risk. In the case of high risk regarding the development of severe infection complications, a parallel SARS-CoV-2 RT-qPCR is needed to be carried out to attain proper diagnostic accuracy and avoid delaying appropriate medical care.