Effectiveness and cost-effectiveness of four different strategies for SARS-CoV-2 surveillance in the general population (CoV-Surv Study): a structured summary of a study protocol for a cluster-randomised, two-factorial controlled trial

Methods for determining clinical utility

Measuring the clinical utility of a diagnostic test involves evaluating its impact on patient outcomes, clinical decision-making, and healthcare resource utilization. Determining clinical utility requires accessing patient medical history and outcomes data. These studies involve enrolling patients undergoing diagnostic tests and tracking their clinical outcomes. Researchers can determine the test's clinical utility by comparing the outcomes of patients who receive the diagnostic test to those who do not. These outcomes include benefits and harm. The highest level of evidence to support clinical utility determinations may be obtained from clinical trials. However, clinical laboratories are often not involved in clinical trials, and laboratory specialists may not be experienced in conducting such trials. Many established laboratory tests have never had clinical utility determined. Prospective studies assessing a diagnostic test's impact on clinical outcomes may require long-term patient monitoring, which is problematic. This paper presents methods that may be used to assess clinical utility.

How are countries responding differently to COVID-19: a systematic review of guidelines on isolation measures

Introduction

Isolation strategies have been implemented in numerous countries worldwide during the ongoing community transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, various countries and organizations have implemented their isolation measures at varying intensities, even during the same period. Therefore, we systematically reviewed the key information contained in currently available guidelines regarding the isolation of the general population, aiming to better identify the heterogeneity of the current isolation strategies.

Methods

We conducted searches in four evidence-based medicine (EBM) databases and five guideline websites to identify guidelines, guidance, protocols, and policy documents published by authoritative advisory bodies or healthcare organizations, which provided information on the implementation of isolation for general populations with COVID-19. One author extracted data using a standardized data extraction checklist, and a second author double-checked all extractions for completeness and correctness. Discrepancies were resolved through discussion. The information extracted from the included articles was summarized both narratively and using tables.

Results

We included 15 articles that provided information on isolation measures recommended by nine different countries and organizations. The included articles consistently recommended isolating individuals with a positive COVID-19 test, regardless of the presence of symptoms. However, there were variations in the duration of isolation, and substantial differences also existed in the criteria for ending the isolation of COVID-19 patients.

Conclusion

Different countries and organizations have substantial differences in their isolation policies. This reminds us that scientifically sound guidelines on isolation that balance the risk of prematurely ending isolation with the burden of prolonged isolation are a crucial topic of discussion when faced with a pandemic.

Seroprevalence of SARS-CoV-2 and Vaccination Coverage among Residents of a Lower-Middle-Class Population in the Federal District, Brazil

Estimating seroprevalence and vaccination coverage against COVID-19 is crucial to the development of well-targeted public health policies at the local level. Here, we estimated seroprevalence and vaccination coverage in a lower-middle-class population in Brazil. We conducted an observational, cross-sectional, population-based survey from 24 September to 19 December 2021. CMIA tests were used to detect anti-SARS-CoV-2 IgG against the N-protein. The overall seroprevalence was 24.15% (177/733), and vaccination coverage was 91.40% (670/733); 72.09% (483/670) were fully vaccinated. Among vaccinated participants, seroprevalence was 24.77% (95% CI 21.50-28.04; 166/670), with a prevalence ratio (PR) of 1.03 (95% CI 0.98-1.08; p-value 0.131). Among participants who received an mRNA vaccine with S-based epitope (485), seroprevalence was 16.29% (95% CI 13.04-19.85; 79/485). Among unvaccinated participants, seroprevalence was 17.46% (95% CI 10.04-28.62; 11/63). Finally, in spite of the political climate and other possible causes for vaccine hesitancy, the positive Brazilian culture towards vaccination might have curbed hesitancy.

Time series analysis revealed prognostic value of continuous nasopharyngeal SARS-CoV-2 nucleic acid quantification for COVID-19: A retrospective study of >3000 COVID-19 patients from 2 centers

BACKGROUND

Early stratification of disease progression remains one of the major challenges towards the post-coronavirus disease 2019 (COVID-19) era. The clinical relevance of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid load is debated due to the heterogeneity in patients' underlying health conditions. We determined the prognostic value of nasopharyngeal viral load dynamic conversion for COVID-19.

METHODS

The cycling threshold (Ct) values of 28,937 nasopharyngeal SARS-CoV-2 RT-PCRs were retrospectively collected from 3,364 COVID-19 patients during hospitalization and coordinated to the onset of disease progression. The ROC curve was utilized to determine the predictive performance of the rate of Ct value alteration between two consecutive RT-PCR runs within 48 h (ΔCt%) for disease transformation across patients with different COVID-19 severity and immune backgrounds, and further validated with 1,860 SARS-CoV-2 RT-PCR results from an independent validation cohort of 262 patients. For the 67 patients with severe COVID-19, Kaplan-Meier analysis was performed to evaluate the difference in survival between patients stratified by the magnitude of Ct value alteration between the late and early stages of hospitalization.

RESULTS

The kinetics of viral nucleic acid conversion diversified across COVID-19 patients with different clinical characteristics and disease severities. The ΔCt% is a clinical characteristic- and host immune status-independent indicator for COVID-19 progression prediction (AUC = 0.79, 95 % CI = 0.76 to 0.81), which outperformed the canonical blood test markers, including c-reactive protein (AUC = 0.57, 95 % CI = 0.53 to 0.61), serum amyloid A (AUC = 0.61, 95 % CI = 0.54 to 0.68), lactate dehydrogenase (AUC = 0.61, 95 % CI = 0.56 to 0.67), d-dimer (AUC = 0.56, 95 % CI = 0.46 to 0.66), and lymphocyte count (AUC = 0.62, 95 % CI = 0.58 to 0.66). Patients with persistent high SARS-CoV-2 viral load (an increase of mean Ct value < 50 %) during the first 3 days of hospitalization demonstrated a significantly unfavorable survival (HR = 0.16, 95 % CI = 0.04 to 0.65, P = 2.41 × 10^-3).

CONCLUSIONS

Viral nucleic acid dynamics of SARS-CoV-2 eliminates the inter-patient variance of basic health conditions and therefore, can serve as a prognostic marker for COVID-19.

From disgusting and complicated to simple and brilliant: Implementation perspectives and lessons learned from users and rejectors of mail-in SARS-CoV-2 gargle tests

Background

Despite the important role of testing as a measure against the COVID-19 pandemic, user perspectives on SARS-CoV-2 tests remain scarce, inhibiting an improvement of testing approaches. As the world enters the third year of the pandemic, more nuanced perspectives of testing, and opportunities to expand testing in a feasible and affordable manner merit consideration.

Methods

Conducted amid the second pandemic wave (late 2020-early 2021) during and after a multi-arm trial evaluating SARS-CoV-2 surveillance strategies in the federal state Baden-Württemberg, Germany, this qualitative sub-study aimed to gain a deeper understanding of how test users and test rejectors perceived mail-in SARS-CoV-2 gargle tests. We conducted 67 semi-structured in-depth interviews (mean duration: 60 min) via telephone or video call. Interviews were audio-recorded, transcribed verbatim and analyzed inductively using thematic analysis. The Consolidated Framework for Implementation Research guided the findings' presentation.

Results

Respondents generally described gargle sampling as simple and comfortable. However, individual perceptions of the testing method and its feasibility varied widely from disgusting and complicated to simple and brilliant. Self-sampling was appreciated for lowering infection risks during testing, but also considered more complex. Gargle-sampling increased participants' self-efficacy to sample correctly. Communication (first contact, quantity and content of information, reminders, support system) and trust (in the study, its institutional affiliation and test method) decisively influenced the intervention's acceptability.

Conclusion

User-driven insights on how to streamline testing include: consider communication, first impressions of tests and information as key for successful mail-in testing; pay attention to the role of mutual trust between those taking and administering tests; implement gargle self-sampling as a pleasant alternative to swab testing; offer multiple test methods to increase test up-take.

Kopfkino: Phases of quarantine among asymptomatic SARS-COV-2 carriers in Germany

Although a majority of SARS-COV-2 diagnosis are asymptomatic, presymptimatic or minimally symptomatic, little has been described and understood about the illness careers of these individuals. This study explored the lived experience of a SARS-COV-2 diagnosis and subsequent quarantine among individuals in Germany who were diagnosed with SARS-COV-2 during the second wave of the pandemic (late 2020-early 2021), but whose diagnosis was unexpected due to a lack of a known contact, or the asymptomatic nature of their case at the time of diagnosis. In-depth interviews (n ​= ​22) were conducted by phone or video call, audio-recorded, and transcribed verbatim. Routine debriefings guided data collection and facilitated analysis, which followed a framework approach. Regardless of age, gender or socioeconomic status, data consistently demonstrated a diagnosis and quarantine career marked by five emotional phases: overconfidence, shock and denial, coming to grips and asking questions, enduring, and cautious optimism as quarantine ended. These experiences suggest that providing trustworthy, easily accessible information regarding certain key aspects of the post diagnosis and quarantine period could benefit patients in terms of reducing stress, understanding the consequences of a diagnosis and mitigating foreseeable challenges in terms of personal, logistical and emotional issues. Follow-up research with providers and public health bureaus could inform how to best tailor such messaging for clients who experience an unexpected diagnosis.

COVID-19 Statistics in the Arab World by the End of October 2022: A Cross-Sectional Study

Background The coronavirus disease 2019 (COVID-19) has affected almost all world countries, including all 22 Arab countries. However, over the last 34 months, the world has suffered from the pandemic unevenly, and COVID-19 statistics are dynamic. Objectives The current study aimed to use COVID-19 data to examine COVID-19 statistics (including the number of cases/deaths/tests) in Arab countries by the end of October 2022 and compare the findings with global statistics. This study was also used to determine the extent to which statistics vary across Arab countries. Methods The primary data on COVID-19 for each Arab country were obtained from the "Worldometer" website. The data include the cumulative incidence of COVID-19 per country, the cumulative number of deaths, the total number of tests performed, the number of cases per million population, the number of deaths per million, the number of tests per million, and the total population. The case-fatality rate (CFR) was calculated (number of deaths/number of cases). In addition, the median age for each Arab country was extracted from the United Nations website. The rate of vaccination coverage (people who received two doses) was extracted from the "Our World in Data" website. COVID-19 statistics were further analyzed in Arab countries in Asia compared to those in Africa at the end of 2020, 2021, and October 2022. To compare the Arab countries to the globe, COVID-19 data for each continent were obtained. The Spearman correlation coefficient was used to determine the relationship between different variables across Arab countries. Results As of November 1, 2022, about 636 million COVID-19 cases and 6.6 million deaths had been recorded worldwide. Arab countries accounted for nearly 2.21% and 2.62% of all cases and deaths, respectively. In general, the mean deaths per million and the mean cases per million for Arab countries were lower than those of the world's countries, although Arab countries recorded a higher mean case-fatality rate. Alternatively, Arab countries in aggregate recorded fewer deaths per million (381) than the world (830). However, statistics across Arab countries have been inconsistent; Arab countries in Africa were less affected. Arab countries have performed approximately 359 million tests (5.29% of all tests), 93% of which were performed by Arab countries in Asia. Moreover, 54.4% of all tests were performed in the United Arab Emirates. Yemen, Somalia, Sudan, Algeria, Syria, Comoros, and Djibouti were the least affected Arab countries based on the number of deaths per million. With the exception of Comoros, these countries were among the least vaccinated in the Arab world. Conclusions In general, Arab countries have been less affected by the COVID-19 pandemic than the rest of the world. However, statistics vary across Arab countries, especially regarding the number of tests performed. Given the natural immunity acquired during the three years and the relatively good vaccine coverage in the Arab world, it is important to reconsider the definition of a suspected case and establish more specific criteria for testing.

Pre-endoscopy coronavirus disease 2019 screening and severe acute respiratory syndrome coronavirus-2 nucleic acid amplification testing in the Veterans Affairs healthcare system: clinical practice patterns, outcomes, and relationship to procedure volume

BACKGROUND AND AIMS

The coronavirus disease 2019 (COVID-19) pandemic has had profound impacts worldwide, including on the performance of GI endoscopy. We aimed to describe the performance and outcomes of pre-endoscopy COVID-19 symptom and exposure screening and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) nucleic acid amplification testing (NAAT) across the national Veterans Affairs healthcare system and describe the relationship of SARS-CoV-2 NAAT use and resumption of endoscopy services.

METHODS

COVID-19 screening and NAAT results from March 2020 to April 2021 were analyzed to determine use, performance characteristics of screening, and association between testing and endoscopic volume trends.

RESULTS

Of 220,891 completed endoscopies identified, 115,890 (52.5%) had documented preprocedure COVID-19 symptom and exposure screenings and 154,127 (69.8%) had preprocedure NAAT results within 7 days before scheduled endoscopy. Of 131,894 total canceled endoscopies, 26,475 (20.1%) had screening data and 28,505 (21.6%) had SARS-CoV-2 NAAT results. Overall, positive NAAT results were reported in 1.8% of all individuals tested and in 1.3% of those who screened negative. Among completed and canceled endoscopies, COVID-19 screening had a 34.6% sensitivity (95% confidence interval [CI], 32.4%-36.8%) and 96.4% specificity (95% CI, 96.2%-96.5%) when compared with NAAT. COVID-19 screening had a positive predictive value of 15.0% (95% CI, 14.0%-16.1%) and a negative predictive value of 98.7% (95% CI, 98.7%-98.8%). There was a very weak correlation between monthly testing and monthly endoscopy volume by site (Spearman rank correlation coefficient = .09).

CONCLUSIONS

These findings have important implications for decisions about preprocedure testing, especially given breakthrough infections among vaccinated individuals during the SARS-CoV-2 delta and omicron variant surge.

On an optimal testing strategy for workplace settings operating during the COVID-19 pandemic

High quality daily testing for the presence of the SARS-CoV-2 in workplace settings has become part of the standard and mandatory protection measures implemented widely in response to the current pandemic. Such tests are often limited to a small fraction of the attending personnel due to cost considerations, limited availability and processing capabilities and the often cumbersome requirements of the test itself. A maximally efficient use of such an important and frequently scarce resource is clearly required. We here present an optimal testing strategy which minimises the presence of pre-symptomatic and asymptomatic infected members of the population in a workplace setting, derived under a series of simplifying statistical assumptions. These assumptions however, retain many of the generalities of the problem and yield robust results, as verified through a number of numerical simulations. We show that reduction in overall infected-person-days, IPD, by significant percentages can be achieved, for fixed numbers of tests per day of 5% and 10% of the population, of 30% and 50% in the IPD numbers, respectively.

Covid-19 Exposure Assessment Tool (CEAT): Easy-to-use tool to quantify exposure based on airflow, group behavior, and infection prevalence in the community.. [PMID: 35291295 PMCID: PMC8923112 DOI: 10.1101/2022.03.02.22271806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The COVID-19 Exposure Assessment Tool (CEAT) allows users to compare respiratory relative risk to SARS-CoV-2 for various scenarios, providing understanding of how combinations of protective measures affect exposure, dose, and risk. CEAT incorporates mechanistic, stochastic and epidemiological factors including the: 1) emission rate of virus, 2) viral aerosol degradation and removal, 3) duration of activity/exposure, 4) inhalation rates, 5) ventilation rates (indoors/outdoors), 6) volume of indoor space, 7) filtration, 8) mask use and effectiveness, 9) distance between people, 10) group size, 11) current infection rates by variant, 12) prevalence of infection and immunity in the community, 13) vaccination rates of the community, and 14) implementation of COVID-19 testing procedures. Demonstration of CEAT, from published studies of COVID-19 transmission events, shows the model accurately predicts transmission. We also show how health and safety professionals at NASA Ames Research Center used CEAT to manage potential risks posed by SARS-CoV-2 exposures. Given its accuracy and flexibility, the wide use of CEAT will have a long lasting beneficial impact in managing both the current COVID-19 pandemic as well as a variety of other scenarios.

Searching for Abiotic Tolerant and Biotic Stress Resistant Wild Lentils for Introgression Breeding Through Predictive Characterization

Crop wild relatives are species related to cultivated plants, whose populations have evolved in natural conditions and confer them valuable adaptive genetic diversity, that can be used in introgression breeding programs. Targeting four wild lentil taxa in Europe, we applied the predictive characterization approach through the filtering method to identify populations potentially tolerant to drought, salinity, and waterlogging. In parallel, the calibration method was applied to select wild populations potentially resistant to lentil rust and broomrape, using, respectively, 351 and 204 accessions evaluated for these diseases. An ecogeographic land characterization map was used to incorporate potential genetic diversity of adaptive value. We identified 13, 1, 21, and 30 populations potentially tolerant to drought, soil salinity, waterlogging, or resistance to rust, respectively. The models targeting broomrape resistance did not adjust well and thus, we were not able to select any population regarding this trait. The systematic use of predictive characterization techniques may boost the efficiency of introgression breeding programs by increasing the chances of collecting the most appropriate populations for the desired traits. However, these populations must still be experimentally tested to confirm the predictions.

The University of Padua salivary-based SARS-CoV-2 surveillance program minimized viral transmission during the second and third pandemic wave

BACKGROUND

The active surveillance of students is proposed as an effective strategy to contain SARS-CoV-2 spread and prevent schools' closure. Saliva for molecular testing is as sensitive as naso-pharyngeal swab (NPS), self-collected and well accepted by participants. This prospective study aimed to verify whether the active surveillance of the Padua University employees by molecular testing of self-collected saliva is an effective and affordable strategy for limiting SARS-CoV-2 spread.

METHODS

A surveillance program based on self-collection of saliva every 2 weeks (October 2020-June 2021) was conducted. Among 8183 employees of the Padua University, a total of 6284 subjects voluntarily took part in the program. Eight collection points guaranteed the daily distribution and collection of barcoded salivary collection devices, which were delivered to the laboratory by a transport service for molecular testing. Quarantine of positive cases and contact tracing were promptly activated.

RESULTS

Among 6284 subjects, 206 individuals were SARS-CoV-2 positive (99 by salivary testing; 107 by NPS performed for contact tracing or symptoms). The cumulative SARS-CoV-2 incidence in this cohort was 3.1%, significantly lower than that of employees not in surveillance (8.0%), in Padua (7.1%) and in the Veneto region (7.2%). Employees with positive saliva results were asymptomatic or had mild symptoms. The levels of serum antibodies after 3 months from the infection were correlated with age and Ct values, being higher in older subjects with greater viral loads.

CONCLUSIONS

Salivary-based surveillance with contact tracing effectively allowed to limit SARS-CoV-2 contagion, also in a population with a high incidence.

Mechanism of Blood-Heart-Barrier Leakage: Implications for COVID-19 Induced Cardiovascular Injury

Although blood–heart-barrier (BHB) leakage is the hallmark of congestive (cardio-pulmonary) heart failure (CHF), the primary cause of death in elderly, and during viral myocarditis resulting from the novel coronavirus variants such as the severe acute respiratory syndrome novel corona virus 2 (SARS-CoV-2) known as COVID-19, the mechanism is unclear. The goal of this project is to determine the mechanism of the BHB in CHF. Endocardial endothelium (EE) is the BHB against leakage of blood from endocardium to the interstitium; however, this BHB is broken during CHF. Previous studies from our laboratory, and others have shown a robust activation of matrix metalloproteinase-9 (MMP-9) during CHF. MMP-9 degrades the connexins leading to EE dysfunction. We demonstrated juxtacrine coupling of EE with myocyte and mitochondria (Mito) but how it works still remains at large. To test whether activation of MMP-9 causes EE barrier dysfunction, we hypothesized that if that were the case then treatment with hydroxychloroquine (HCQ) could, in fact, inhibit MMP-9, and thus preserve the EE barrier/juxtacrine signaling, and synchronous endothelial-myocyte coupling. To determine this, CHF was created by aorta-vena cava fistula (AVF) employing the mouse as a model system. The sham, and AVF mice were treated with HCQ. Cardiac hypertrophy, tissue remodeling-induced mitochondrial-myocyte, and endothelial-myocyte contractions were measured. Microvascular leakage was measured using FITC-albumin conjugate. The cardiac function was measured by echocardiography (Echo). Results suggest that MMP-9 activation, endocardial endothelial leakage, endothelial-myocyte (E-M) uncoupling, dyssynchronous mitochondrial fusion-fission (Mfn2/Drp1 ratio), and mito-myocyte uncoupling in the AVF heart failure were found to be rampant; however, treatment with HCQ successfully mitigated some of the deleterious cardiac alterations during CHF. The findings have direct relevance to the gamut of cardiac manifestations, and the resultant phenotypes arising from the ongoing complications of COVID-19 in human subjects.

COVID-19 and metabolic disease: mechanisms and clinical management

Up to 50% of the people who have died from COVID-19 had metabolic and vascular disorders. Notably, there are many direct links between COVID-19 and the metabolic and endocrine systems. Thus, not only are patients with metabolic dysfunction (eg, obesity, hypertension, non-alcoholic fatty liver disease, and diabetes) at an increased risk of developing severe COVID-19 but also infection with SARS-CoV-2 might lead to new-onset diabetes or aggravation of pre-existing metabolic disorders. In this Review, we provide an update on the mechanisms of how metabolic and endocrine disorders might predispose patients to develop severe COVID-19. Additionally, we update the practical recommendations and management of patients with COVID-19 and post-pandemic. Furthermore, we summarise new treatment options for patients with both COVID-19 and diabetes, and highlight current challenges in clinical management.

Performance and cost-effectiveness of a pooled testing strategy for SARS-CoV-2 using real-time polymerase chain reaction in Uganda

Real-time polymerase chain reaction (RT-PCR) remains the gold standard for detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This study tested the performance of a pooled testing strategy for RT-PCR and its cost-effectiveness. In total, 1280 leftover respiratory samples collected between 19 April and 6 May 2021 were tested in 128 pools of 10 samples each, out of which 16 pools were positive. The positivity rate of the unpooled samples was 1.9% (24/1280). After parallel testing using the individual and pooled testing strategies, positive agreement was 100% and negative agreement was 99.8%. The overall median cycle threshold (Ct) value of the unpooled samples was 29.8 (interquartile range 22.3-34.3). Pools that remained positive when compared with the results of individual samples had lower median Ct values compared with those that turned out to be negative (28.8 versus 34.8; P=0.0.035). Pooled testing reduced the cost >4-fold. Pooled testing may be a more cost-effective approach to diagnose SARS-CoV-2 in resource-limited settings without compromising diagnostic performance.

Rapid incidence estimation from SARS-CoV-2 genomes reveals decreased case detection in Europe during summer 2020

By October 2021, 230 million SARS-CoV-2 diagnoses have been reported. Yet, a considerable proportion of cases remains undetected. Here, we propose GInPipe, a method that rapidly reconstructs SARS-CoV-2 incidence profiles solely from publicly available, time-stamped viral genomes. We validate GInPipe against simulated outbreaks and elaborate phylodynamic analyses. Using available sequence data, we reconstruct incidence histories for Denmark, Scotland, Switzerland, and Victoria (Australia) and demonstrate, how to use the method to investigate the effects of changing testing policies on case ascertainment. Specifically, we find that under-reporting was highest during summer 2020 in Europe, coinciding with more liberal testing policies at times of low testing capacities. Due to the increased use of real-time sequencing, it is envisaged that GInPipe can complement established surveillance tools to monitor the SARS-CoV-2 pandemic. In post-pandemic times, when diagnostic efforts are decreasing, GInPipe may facilitate the detection of hidden infection dynamics.

A seroprevalence survey of anti-SARS-CoV-2 antibodies among individuals 18 years of age or older living in a vulnerable region of the city of São Paulo, Brazil

A second wave of COVID-19 has demonstrated how challenging it will be to achieve sustained control of the disease, even with vaccination underway in many countries. Therefore, it remains relevant to keep improving our understanding of the distribution of COVID-19, especially of asymptomatic individuals, among different populations, and particularly in vulnerable regions. Hence, this population-based serosurvey had the objective of estimating the prevalence of individuals 18 years of age or older infected by SARS-CoV-2, and the proportion of asymptomatic individuals, among a vulnerable population living in an urban setting. This was a cross-sectional single-stage cluster sampling serosurvey conducted between September and December of 2019, in a vulnerable region of the city of São Paulo, Brazil. Families covered by three public primary healthcare units represented the selected clusters. After study inclusion, participants were asked about signs and symptoms related to COVID-19, and had collected 10 mL of blood for serology testing. A total of 272 individuals from 185 families were included in the study, out of the 400 eligible individuals for inclusion, resulting in a non-response rate of 32%. The post stratified prevalence of individuals infected by SARS-CoV-2 was 45.2% (95% CI: 39.4–51.0%), with a proportion of asymptomatic cases of 30.2% (95% CI: 23.3–38.0%). This population-based serosurvey identified a greater prevalence of infected individuals by SARS-CoV-2 compared to data from the beginning of the pandemic, and from a recent citywide serosurvey, with a similar proportion of asymptomatic individuals. It demonstrated the value of primary healthcare services for disease surveillance activities, and the importance of more focused serosurveys, especially in vulnerable locations, and the need to evaluate new surveillance strategies to take into account asymptomatic cases.

The Impact of Increasing Disease Prevalence, False Omissions, and Diagnostic Uncertainty on Coronavirus Disease 2019 (COVID-19) Test Performance

CONTEXT.—

Coronavirus disease 2019 (COVID-19) test performance depends on predictive values in settings of increasing disease prevalence. Geospatially distributed diagnostics with minimal uncertainty facilitate efficient point-of-need strategies.

OBJECTIVES.—

To use original mathematics to interpret COVID-19 test metrics; assess US Food and Drug Administration Emergency Use Authorizations and Health Canada targets; compare predictive values for multiplex, antigen, polymerase chain reaction kit, point-of-care antibody, and home tests; enhance test performance; and improve decision-making.

DESIGN.—

PubMed/newsprint-generated articles documenting prevalence. Mathematica and open access software helped perform recursive calculations, graph multivariate relationships, and visualize performance by comparing predictive value geometric mean-squared patterns.

RESULTS.—

Tiered sensitivity/specificity comprised: T1, 90%, 95%; T2, 95%, 97.5%; and T3, 100%, ≥99%. Tier 1 false negatives exceeded true negatives at >90.5% prevalence; false positives exceeded true positives at <5.3% prevalence. High-sensitivity/specificity tests reduced false negatives and false positives, yielding superior predictive values. Recursive testing improved predictive values. Visual logistics facilitated test comparisons. Antigen test quality fell off as prevalence increased. Multiplex severe acute respiratory syndrome (SARS)-CoV-2)*influenza A/B*respiratory syncytial virus testing performed reasonably well compared with tier 3. Tier 3 performance with a tier 2 confidence band lower limit will generate excellent performance and reliability.

CONCLUSIONS.—

The overriding principle is to select the best combined performance and reliability pattern for the prevalence bracket. Some public health professionals recommend repetitive testing to compensate for low sensitivity. More logically, improved COVID-19 assays with less uncertainty conserve resources. Multiplex differentiation of COVID-19 from influenza A/B-respiratory syncytial virus represents an effective strategy if seasonal flu surges next year.