Saliva in the Diagnosis of COVID-19: A Review and New Research Directions

This review presents literature that highlights saliva's utility as a biofluid in the diagnosis and monitoring of COVID-19. A systematic search was performed in 5 electronic databases (PubMed, Embase, LILACS, Scopus, and Web of Science). Studies were eligible for inclusion if they assessed the potential diagnostic value and/or other discriminatory properties of biological markers in the saliva of patients with COVID-19. As of July 22, 2020, a total of 28 studies have investigated the presence of SARS-CoV-2 RNA in saliva. Several of those studies confirmed reliable detection of SARS-CoV-2 in the saliva of patients with COVID-19. Saliva offered sensitivity and specificity for SARS-CoV-2 detection comparable to that of the current standard of nasopharyngeal and throat swabs. However, the utility of saliva in diagnosing COVID-19 infection remains understudied. Clinical studies with larger patient populations that measure recordings at different stages during the disease are still necessary to confirm the accuracy of COVID-19 diagnosis with saliva. Nevertheless, the utility of saliva as a diagnostic tool opens the possibility of using rapid and less invasive diagnostic strategies by targeting bioanalytes rather than the pathogen.

Diagnostic accuracy of a SARS-CoV-2 rapid antigen test in real-life clinical settings

Background

Laboratory tests are a mainstay in managing the COVID-19 pandemic, and high hopes are placed on rapid antigen tests. However, the accuracy of rapid antigen tests in real-life clinical settings is unclear because adequately designed diagnostic accuracy studies are essentially lacking.

Objectives

The aim of this study was to assess the accuracy of a rapid antigen test in diagnosing SARS-CoV-2 infection in a primary/secondary care testing facility.

Methods

Consecutive individuals presenting at a COVID-19 testing facility affiliated to a Swiss University Hospital were recruited (n = 1465%). Nasopharyngeal swabs were obtained, and the Roche/SD Biosensor rapid antigen test was conducted in parallel with two real-time PCR tests (reference standard).

Results

Among the 1465 patients recruited, RT-PCR was positive in 141 individuals, corresponding to a prevalence of 9.6%. The Roche/SD Biosensor rapid antigen test was positive in 94 patients (6.4%), and negative in 1368 individuals (93.4%; insufficient sample material in 3 patients). The overall sensitivity of the rapid antigen test was 65.3% (95% confidence interval [CI] 56.8–73.1), the specificity was 99.9% (95% CI 99.5–100.0). In asymptomatic individuals, the sensitivity was 44.0% (95% CI 24.4–65.1).

Conclusions

The accuracy of the SARS-CoV-2 Roche/SD Biosensor rapid antigen test in diagnosing SARS-CoV-2 infections in a primary/secondary care testing facility was considerably lower compared with the manufacturer's data. Widespread application in such a setting might lead to a considerable number of individuals falsely classified as SARS-CoV-2 negative.

Specificity and positive predictive value of SARS-CoV-2 nucleic acid amplification testing in a low-prevalence setting

Objectives

When the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is low, many positive test results are false positives. Confirmatory testing reduces overdiagnosis and nosocomial infection and enables real-world estimates of test specificity and positive predictive value. This study estimates these parameters to evaluate the impact of confirmatory testing and to improve clinical diagnosis, epidemiological estimation and interpretation of vaccine trials.

Methods

Over 1 month we took all respiratory samples from our laboratory with a patient's first detection of SARS-CoV-2 RNA (Hologic Aptima SARS-CoV-2 assay or in-house RT-PCR platform), and repeated testing using two platforms. Samples were categorized by source, and by whether clinical details suggested COVID-19 or corroborative testing from another laboratory. We estimated specificity and positive predictive value using approaches based on maximum likelihood.

Results

Of 19 597 samples, SARS-CoV-2 RNA was detected in 107; 52 corresponded to first-time detection (0.27% of tests on samples without previous detection). Further testing detected SARS-CoV-2 RNA once or more (‘confirmed’) in 29 samples (56%), and failed to detect SARS-CoV-2 RNA (‘not confirmed’) in 23 (44%). Depending upon assumed parameters, point estimates for specificity and positive predictive value were 99.91–99.98% and 61.8–89.8% respectively using the Hologic Aptima SARS-CoV-2 assay, and 97.4–99.1% and 20.1–73.8% respectively using an in-house assay.

Conclusions

Nucleic acid amplification testing for SARS-CoV-2 is highly specific. Nevertheless, when prevalence is low a significant proportion of initially positive results fail to confirm, and confirmatory testing substantially reduces the detection of false positives. Omitting additional testing in samples with higher prior detection probabilities focuses testing where it is clinically impactful and minimizes delay.

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

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

Innovative screening tests for COVID-19 in South Korea

Recently, the number of Corona Virus Disease 2019 (COVID-19) cases has increased remarkably in South Korea, so the triage clinics and emergency departments (ED) are expected to be overcrowded with patients with presumed infection. As of March 21st, there was a total of 8,799 confirmed cases of COVID-19 and 102 related deaths in South Korea that was one of the top countries with high incidence rates [1]. This sharp increase in infection is associated with 1) outbreaks in individual provinces, 2) deployment of rapid and aggressive screening tests, 3) dedicated healthcare staffs for virus screening tests, 4) quarantine inspection data transparency and accurate data reporting, and 5) public health lessons from previous Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) outbreaks. This commentary introduces innovative screening tests that are currently used in South Korea for COVID-19, e.g., Drive-Through and Walk-Through tests, and compare the advantages and disadvantages of both methods.

Effects of Tanreqing Capsule on the negative conversion time of nucleic acid in patients with COVID-19: A retrospective cohort study

Objective

Traditional Chinese medicine plays a significant role in the treatment of the pandemic of coronavirus disease 2019 (COVID-19). Tanreqing Capsule (TRQC) was used in the treatment of COVID-19 patients in the Shanghai Public Health Clinical Center. This study aimed to investigate the clinical efficacy of TRQC in the treatment of COVID-19.

Methods

A retrospective cohort study was conducted on 82 patients who had laboratory-confirmed mild and moderate COVID-19; patients were treated with TRQC in one designated hospital. The treatment and control groups consisted of 25 and 57 cases, respectively. The treatment group was given TRQC orally three times a day, three pills each time, in addition to conventional Western medicine treatments which were also administered to the control group. The clinical efficacy indicators, such as the negative conversion time of pharyngeal swab nucleic acid, the negative conversion time of fecal nucleic acid, the duration of negative conversion of pharyngeal-fecal nucleic acid, and the improvement in the level of immune indicators such as T-cell subsets (CD3, CD4 and CD45) were monitored.

Results

COVID-19 patients in the treatment group, compared to the control group, had a shorter negative conversion time of fecal nucleic acid (4 vs. 9 days, P = 0.047) and a shorter interval of negative conversion of pharyngeal-fecal nucleic acid (0 vs. 2 days, P = 0.042). The level of CD3⁺ T cells increased in the treatment group compared to the control group ([317.09 ± 274.39] vs. [175.02 ± 239.95] counts/μL, P = 0.030). No statistically significant differences were detected in the median improvement in levels of CD4⁺ T cells (173 vs. 107 counts/μL, P = 0.208) and CD45⁺ T cells (366 vs. 141 counts/μL, P = 0.117) between the treatment and control groups.

Conclusion

Significant reductions in the negative conversion time of fecal nucleic acid and the duration of negative conversion of pharyngeal-fecal nucleic acid were identified in the treatment group as compared to the control group, illustrating the potential therapeutic benefits of using TRQC as a complement to conventional medicine in patients with mild and moderate COVID-19. The underlying mechanism may be related to the improved levels of the immune indicator CD3⁺ T cells.

Implementation of a Deep Learning-Based Computer-Aided Detection System for the Interpretation of Chest Radiographs in Patients Suspected for COVID-19

OBJECTIVE

To describe the experience of implementing a deep learning-based computer-aided detection (CAD) system for the interpretation of chest X-ray radiographs (CXR) of suspected coronavirus disease (COVID-19) patients and investigate the diagnostic performance of CXR interpretation with CAD assistance.

MATERIALS AND METHODS

In this single-center retrospective study, initial CXR of patients with suspected or confirmed COVID-19 were investigated. A commercialized deep learning-based CAD system that can identify various abnormalities on CXR was implemented for the interpretation of CXR in daily practice. The diagnostic performance of radiologists with CAD assistance were evaluated based on two different reference standards: 1) real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) results for COVID-19 and 2) pulmonary abnormality suggesting pneumonia on chest CT. The turnaround times (TATs) of radiology reports for CXR and rRT-PCR results were also evaluated.

RESULTS

Among 332 patients (male:female, 173:159; mean age, 57 years) with available rRT-PCR results, 16 patients (4.8%) were diagnosed with COVID-19. Using CXR, radiologists with CAD assistance identified rRT-PCR positive COVID-19 patients with sensitivity and specificity of 68.8% and 66.7%, respectively. Among 119 patients (male:female, 75:44; mean age, 69 years) with available chest CTs, radiologists assisted by CAD reported pneumonia on CXR with a sensitivity of 81.5% and a specificity of 72.3%. The TATs of CXR reports were significantly shorter than those of rRT-PCR results (median 51 vs. 507 minutes; p < 0.001).

CONCLUSION

Radiologists with CAD assistance could identify patients with rRT-PCR-positive COVID-19 or pneumonia on CXR with a reasonably acceptable performance. In patients suspected with COVID-19, CXR had much faster TATs than rRT-PCRs.

Molecular analysis of several in-house rRT-PCR protocols for SARS-CoV-2 detection in the context of genetic variability of the virus in Colombia

The COVID-19 pandemic caused by SARS-CoV-2 is a public health problem unprecedented in the recent history of humanity. Different in-house real-time RT-PCR (rRT-PCR) methods for SARS-CoV-2 diagnosis and the appearance of genomes with mutations in primer regions have been reported. Hence, whole-genome data from locally-circulating SARS-CoV-2 strains contribute to the knowledge of its global variability and the development and fine tuning of diagnostic protocols. To describe the genetic variability of Colombian SARS-CoV-2 genomes in hybridization regions of oligonucleotides of the main in-house methods for SARS-CoV-2 detection, RNA samples with confirmed SARS-CoV-2 molecular diagnosis were processed through next-generation sequencing. Primers/probes sequences from 13 target regions for SARS-CoV-2 detection suggested by 7 institutions and consolidated by WHO during the early stage of the pandemic were aligned with Muscle tool to assess the genetic variability potentially affecting their performance. Finally, the corresponding codon positions at the 3' end of each primer, the open reading frame inspection was identified for each gene/protein product. Complete SARS-CoV-2 genomes were obtained from 30 COVID-19 cases, representative of the current epidemiology in the country. Mismatches between at least one Colombian sequence and five oligonucleotides targeting the RdRP and N genes were observed. The 3' end of 4 primers aligned to the third codon position, showed high risk of nucleotide substitution and potential mismatches at this critical position. Genetic variability was detected in Colombian SARS-CoV-2 sequences in some of the primer/probe regions for in-house rRT-PCR diagnostic tests available at WHO COVID-19 technical guidelines; its impact on the performance and rates of false-negative results should be experimentally evaluated. The genomic surveillance of SARS-CoV-2 is highly recommended for the early identification of mutations in critical regions and to issue recommendations on specific diagnostic tests to ensure the coverage of locally-circulating genetic variants.

Chest x-ray severity score in COVID-19 patients on emergency department admission: a two-centre study

BACKGROUND

Integration of imaging and clinical parameters could improve the stratification of COVID-19 patients on emergency department (ED) admission. We aimed to assess the extent of COVID-19 pulmonary abnormalities on chest x-ray (CXR) using a semiquantitative severity score, correlating it with clinical data and testing its interobserver agreement.

METHODS

From February 22 to April 8, 2020, 926 consecutive patients referring to ED of two institutions in Northern Italy for suspected SARS-CoV-2 infection were reviewed. Patients with reverse transcriptase-polymerase chain reaction positive for SARS-CoV-2 and CXR images on ED admission were included (295 patients, median age 69 years, 199 males). Five readers independently and blindly reviewed all CXRs, rating pulmonary parenchymal involvement using a 0-3 semiquantitative score in 1-point increments on 6 lung zones (range 0-18). Interobserver agreement was assessed with weighted Cohen's κ, correlations between median CXR score and clinical data with Spearman's ρ, and the Mann-Whitney U test.

RESULTS

Median score showed negative correlation with SpO₂ (ρ = -0.242, p < 0.001), positive correlation with white cell count (ρ = 0.277, p < 0.001), lactate dehydrogenase (ρ = 0.308, p < 0.001), and C-reactive protein (ρ = 0.367, p < 0.001), being significantly higher in subsequently dead patients (p = 0.003). Considering overall scores, readers' pairings yielded moderate (κ = 0.449, p < 0.001) to almost perfect interobserver agreement (κ = 0.872, p < 0.001), with better interobserver agreement between readers of centre 2 (up to κ = 0.872, p < 0.001) than centre 1 (κ = 0.764, p < 0.001).

CONCLUSIONS

Proposed CXR pulmonary severity score in COVID-19 showed moderate to almost perfect interobserver agreement and significant but weak correlations with clinical parameters, potentially furthering CXR integration in patients' stratification.

Risk Factors for Testing Positive for Severe Acute Respiratory Syndrome Coronavirus 2 in a National United States Healthcare System

BACKGROUND

Identifying risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection could help health systems improve testing and screening strategies. The aim of this study was to identify demographic factors, comorbid conditions, and symptoms independently associated with testing positive for SARS-CoV-2.

METHODS

This was an observational cross-sectional study at the Veterans Health Administration, including persons tested for SARS-CoV-2 nucleic acid by polymerase chain reaction (PCR) between 28 February and 14 May 2020. Associations between demographic characteristics, diagnosed comorbid conditions, and documented symptoms with testing positive for SARS-CoV-2 were measured.

RESULTS

Of 88 747 persons tested, 10 131 (11.4%) were SARS-CoV-2 PCR positive. Positivity was associated with older age (≥80 vs <50 years: adjusted odds ratio [aOR], 2.16 [95% confidence interval {CI}, 1.97-2.37]), male sex (aOR, 1.45 [95% CI, 1.34-1.57]), regional SARS-CoV-2 burden (≥2000 vs <400 cases/million: aOR, 5.43 [95% CI, 4.97-5.93]), urban residence (aOR, 1.78 [95% CI, 1.70-1.87]), black (aOR, 2.15 [95% CI, 2.05-2.26]) or American Indian/Alaska Native Hawaiian/Pacific Islander (aOR, 1.26 [95% CI, 1.05-1.52]) vs white race, and Hispanic ethnicity (aOR, 1.52 [95% CI, 1.40-1.65]). Obesity and diabetes were the only 2 medical conditions associated with testing positive. Documented fevers, chills, cough, and diarrhea were also associated with testing positive. The population attributable fraction of positive tests was highest for geographic location (35.3%), followed by demographic variables (27.1%), symptoms (12.0%), obesity (10.5%), and diabetes (0.4%).

CONCLUSIONS

The majority of positive SARS-CoV-2 tests were attributed to geographic location, demographic characteristics, and obesity, with a minor contribution of chronic comorbid conditions.

Self-Collected versus Healthcare Worker-Collected Swabs in the Diagnosis of Severe Acute Respiratory Syndrome Coronavirus 2

The aim of this study was to compare the sensitivity of self-collected versus healthcare worker (HCW)-collected swabs for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) testing. Symptomatic individuals referred for SARS-CoV-2 testing were invited to provide mobile-phone video-instructed self-collected oropharyngeal and nasal samples followed by a HCW-collected oropharyngeal sample. All samples were sent for analysis to the same microbiology laboratory, and the number of SARS-CoV-2-positive participants in the two tests was compared. A total of 109 participants were included, and 19 participants had SARS-CoV-2-positive results. The diagnostic sensitivity of the self-collected and HCW-collected swabs was 84.2% and 89.5%, respectively, with an acceptable agreement, Cohens kappa 0.82, p < 0.001. Further, results from a questionnaire answered by the participants found that loss of smell as a self-reported symptom was a strong predictor for a SARS-CoV-2-positive test. In conclusion, we found that self-collected oropharyngeal and nasal swabs for SARS-CoV-2 testing can be reliable compared to HCW-collected oropharyngeal samples.

Bringing radiology to patient's home using mobile equipment: A weapon to fight COVID-19 pandemic

Because of coronavirus disease 2019 (COVID-19) high contagiousness, it is crucial to identify and promptly isolate COVID-19 patients. In this context, chest imaging examinations, in particular chest x-ray (CXR), can play a pivotal role in different settings, to triage in case of unavailability, delay of or first negative result of reverse transcriptase-polymerase chain reaction (RT-PCR), and to stratify disease severity. Considering the need to reduce, as much as possible, hospital admission of patients with suspected or confirmed infection, the use of mobile x-ray equipment could represent a safe approach. We picture a potential sequence of events, involving a team composed by a radiographer and a nurse, going to patient's home to perform CXR, nasopharyngeal swab (and, if needed, also a blood sample), with fast radiologist tele-reporting, and resulting patient management approach (home isolation or emergency room admission, when needed). This approach brings healthcare to patient's home, reducing the risk of infected subjects referring to family doctors' office or emergency departments, and strengthening community medicine while maintaining a strong connection with radiology departments.

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Chest x-ray and computed tomography can play a pivotal role in COVID-19 pandemic.

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Mobile x-ray at patient's house or nursing home could represent a safe approach reducing social contacts during pandemic.

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Domiciliary radiography reduces the risk of infected subjects referring to family doctors’ office or emergency departments.

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This procedure can reduce general practitioner visit, nurse performing swab and transportation to the hospital costs.

Accuracy of a Novel SARS-CoV-2 Antigen-Detecting Rapid Diagnostic Test from Standardized Self-Collected Anterior Nasal Swabs

Background Antigen-detecting rapid diagnostic tests (Ag-RDT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) offer new opportunities for the quick and laboratory-independent identification of infected individuals for control of the SARS-CoV-2 pandemic. Despite the potential benefits, nasopharyngeal sample collection is frequently perceived as uncomfortable by patients and requires trained healthcare personnel with protective equipment. Therefore, anterior nasal self-sampling is increasingly recognized as a valuable alternative. Methods We performed a prospective, single-center, point of care validation of an Ag-RDT using a polypropylene absorbent collector for standardized self-collected anterior nasal swabs. Real-time polymerase chain reaction (RT-PCR) from combined oropharyngeal/nasopharyngeal swabs served as a comparator. Primary endpoint was sensitivity of the standardized Ag-RDT in symptomatic patients with medium or high viral concentration (≥1 million RNA copies on RT-PCR for SARS-CoV-2). Results Between 12 February and 22 March 2021, 388 participants were enrolled. After exclusion of 9 patients for which no PCR result could be obtained, the novel Ag-RDT was evaluated based on 379 participants, of whom 273 were symptomatic and 106 asymptomatic. In 61 samples from symptomatic patients with medium or high viral load (≥1 million RNA copies), the sensitivity of the standardized Ag-RDT was 96.7% (59/61; 95% confidence interval (CI): 88.7–99.6%) for the primary endpoint. In total, 62 positive Ag-RDT results were detected out of 70 RT-PCR positive individuals, yielding an overall sensitivity of 88.6% (95% CI: 78.7–94.9%). Specificity was 99.7% (95% CI: 98.2–100%) in 309 RT-PCR negative individuals. Conclusions Here, we present a validation of a novel Ag-RDT with a standardized sampling process for anterior nasal self-collection, which meets World Health Organisation (WHO) criteria of ≥80% sensitivity and ≥97% specificity. Although less sensitive than RT-PCR, this assay could be beneficial due to its rapid results, ease of use, and suitability for standardized self-testing.

The dark side of SARS-CoV-2 rapid antigen testing: screening asymptomatic patients

Several reports showed SARS-CoV-2 rapid antigen tests (RATs) performances among COVID-19 symptomatic subjects in outpatient settings during periods of highest incidence of infections and high rates of hospital admissions, but few data are present for asymptomatic patients. We investigated the role of RATs in an emergency department, as a novel screening tool before admission for COVID-19 asymptomatic patients. A total of 116 patients were screened on admission in a 250-bed community hospital in Morges, Switzerland. RAT detected 2/7 RT-PCR-positive patients and delivered two false-positive results. These data suggest the non-fiability of RATs screening in this clinical scenario.

Duration of SARS-CoV-2 RNA detection in COVID-19 patients in home isolation, Rhineland-Palatinate, Germany, 2020 - an interval-censored survival analysis

We analysed consecutive RT-qPCR results of 537 symptomatic coronavirus disease (COVID-19) patients in home quarantine. Respectively 2, 3, and 4 weeks after symptom onset, 50%, 25% and 10% of patients had detectable RNA from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In patients with mild COVID-19, RNA detection is likely to outlast currently known periods of infectiousness by far and fixed time periods seem more appropriate in determining the length of home isolation than laboratory-based approaches.

Pharmacists' Willingness to Provide Coronavirus Disease (COVID-19) Services and the Needs to Support COVID-19 Testing, Management, and Prevention

The need for increased testing is pivotal in the response to the coronavirus disease (COVID-19) pandemic. Recently, through the Public Readiness and Emergency Preparedness (PREP) Act, pharmacists were given the ability to order and administer COVID-19 tests, giving them a better opportunity to engage in the pandemic response across the nation as well as in Idaho. This survey sought to determine Idaho pharmacists’ willingness to provide different COVID-19 related services, assess needed resources to provide such services, and identify and prioritize other unmet community needs. We conducted a nine-question, cross-sectional survey distributed to pharmacists with addresses located in Idaho. All questions in the survey were optional and focused on pharmacist’s willingness to provide services, what resources and additional training they would need, difficulty with 90-day prescriptions, and solicited additional feedback using an open-ended question. A total of 229 responses were received, representing all areas of pharmacy practice, with approximately half from community settings. The majority of respondents (70%) were willing to provide COVID-19 testing. Adequate staffing, changes to workflow, and the need for billing and clear reimbursement mechanisms were most frequently cited as barriers to contributing to the COVID-19 response. In summary, we found that pharmacists are very willing to help during this crisis, but their involvement may be better facilitated with the removal of barriers.

Variplex™ test system fails to reliably detect SARS-CoV-2 directly from respiratory samples without RNA extraction

Diagnosis of COVID is performed by PCR methods, but their capacity is limited by the requirement of high-level facilities and instruments. The loop-mediated isothermal amplification (LAMP) method has been utilized for the detection of isolated virus-specific RNA. Preliminary data suggest the possibility of isothermal amplification directly from respiratory samples without RNA extraction. All patients admitted to our hospital were screened for SARS-CoV-2 by routine. Respiratory samples were tested by variplex system based on LAMP method directly without RNA extraction and by PCR. Primary endpoint was the false-negative rate of variplex test compared with PCR as gold standard. In 109 patients variplex test and PCR assay were performed simultaneously. Median age was 80 years and male/female ratio was 40/60%. The prevalence of PCR-confirmed COVID diagnosis was 43.1%. Variplex test was positive in 13.8%. False-negative rate of variplex test compared with PCR was 83.0%. The potential of LAMP technology using isolated RNA has been demonstrated impressively by others, and excellent sensitivity and specificity of detecting SARS-CoV-2 has been reported. However, without RNA extraction, the variplex test system failed to reliably detect SARS-CoV-2 directly in respiratory samples.

Predictors of COVID-19 testing rates: A cross-country comparison

OBJECTIVES

Cross-country comparisons of coronavirus disease (COVID-19) have largely been applied to mortality analyses. The goal of this analysis is to explore predictors of COVID-19 testing through cross-country comparisons, to better inform international health policies.

METHODS

Testing and case-based data were amassed from Our World in Data, and information regarding predictors was gathered from the World Bank. We investigate Human Development Index (HDI), health expenditure, universal health coverage (UHC), urban population, service industry workers (%), and air pollution as predictors. We explored testing data through July 31, 2020, or most recently available, using case-indexing methods, which involve synchronizing countries by date of first reported COVID-19 case as an index date and normalizing to the cumulative tests 25 days post-index date. Three multivariable linear regression models were built in a stepwise fashion to explore the association between the indexed number of COVID-19 tests and HDI scores.

RESULTS

A total of 86 countries were included in the final analytical sample, excluding countries with missing data. HDI and urban population were found to be significantly associated with testing levels.

CONCLUSIONS

Results suggest that social conditions and government capacity remain consistently salient in the consideration of testing rates. International efforts to assist low-HDI countries are needed to support the global COVID-19 response.

Data Sharing Solutions for Biobanks for the COVID-19 Pandemic

The coronavirus disease 2019 (COVID-19) is a novel illness, which is not fully understood. Whether an individual has traveled outside their respective country or never left their community, COVID-19 is a highly contagious illness, which can result in high death rates. Biobanks will play a role in providing tools to examine data from those receiving treatment along with reviewing the current and long treatment outcomes associated with this novel coronavirus disease. A diverse, global network made up of laboratory scientists, clinical researchers, epidemiologists, data science teams, physicians, and so on must have a standardized, collaborative, virtual biobanking solution to share clinical expertise and evidence-based solutions. This virtual biobank must be centrally managed to ensure standardized quality assurance and quality control efforts. Virtual biobanks will eliminate the need to transport samples between two locations for a specific study, minimizing the risk of contamination. It is necessary for virtual biobanks to upload imaging data from those patients diagnosed with COVID-19. Standardized, collected information will be essential in the area of discovery and validation of disease markers as well as novel therapeutic strategies. It is essential for biobanks to collect COVID-19 specimens along with corresponding clinical and demographic data from COVID-19 diagnostic testing. Because COVID-19 is an acute respiratory illness, proper collection procedures must be in place to collect respiratory samples for biobanking purposes. A preconfigured purpose-built COVID-19 Laboratory Information Management System (LIMS) is an efficient tool to seamlessly manage a data sharing network. Data entered into LIMS will be beneficial in designing much needed clinical trials to address any unmet needs to better address clinical treatment and outcomes. The partners or entities associated with the COVID-19 data sharing network will be able to effectively communicate, view data, and images associated with their respective research interest to advance COVID-19 research and data driven, clinical care.

Acceptability, Usability, and Performance of Lateral Flow Immunoassay Tests for Severe Acute Respiratory Syndrome Coronavirus 2 Antibodies: REACT-2 Study of Self-Testing in Nonhealthcare Key Workers

BACKGROUND

Seroprevalence studies are essential to understand the epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Various technologies, including laboratory assays and point-of-care self-tests, are available for antibody testing. The interpretation of seroprevalence studies requires comparative data on the performance of antibody tests.

METHODS

In June 2020, current and former members of the United Kingdom police forces and fire service performed a self-test lateral flow immunoassay (LFIA), had a nurse-performed LFIA, and provided a venous blood sample for enzyme-linked immunosorbent assay (ELISA). We present the prevalence of antibodies to SARS-CoV-2 and the acceptability and usability of self-test LFIAs, and we determine the sensitivity and specificity of LFIAs compared with laboratory ELISA.

RESULTS

In this cohort of 5189 current and former members of the police service and 263 members of the fire service, 7.4% (396 of 5348; 95% confidence interval [CI], 6.7-8.1) were antibody positive. Seroprevalence was 8.9% (95% CI, 6.9-11.4) in those under 40 years, 11.5% (95% CI, 8.8-15.0) in those of nonwhite ethnicity, and 7.8% (95% CI, 7.1-8.7) in those currently working. Self-test LFIA had an acceptability of 97.7% and a usability of 90.0%. There was substantial agreement between within-participant LFIA results (kappa 0.80; 95% CI, 0.77-0.83). The LFIAs had a similar performance: compared with ELISA, sensitivity was 82.1% (95% CI, 77.7-86.0) self-test and 76.4% (95% CI, 71.9-80.5) nurse-performed with specificity of 97.8% (95% CI, 97.3-98.2) and 98.5% (95% CI, 98.1-98.8), respectively.

CONCLUSIONS

A greater proportion of this nonhealthcare key worker cohort showed evidence of previous infection with SARS-CoV-2 than the general population at 6.0% (95% CI, 5.8-6.1) after the first wave in England. The high acceptability and usability reported by participants and similar performance of self-test and nurse-performed LFIAs indicate that the self-test LFIA is fit for purpose for home testing in occupational and community prevalence studies.

Using Prenatal Blood Samples to Evaluate COVID-19 Rapid Serologic Tests Specificity

INTRODUCTION

Background cross-reactivity with other coronaviruses may reduce the specificity of COVID-19 rapid serologic tests. The vast majority of women attend prenatal care, which is a unique source of population-based blood samples appropriate for validation studies. We used stored 2018 serum samples from an existing pregnancy cohort study to evaluate the specificity of COVID-19 serologic rapid diagnostic tests.

METHODS

We randomly selected 120 stored serum samples from pregnant women enrolled in a cohort in 2018 in Tegucigalpa, Honduras, at least 1 year before the COVID-19 pandemic. We used stored serum to evaluate four lateral flow rapid diagnostic tests, following manufacturers' instructions. Pictures were taken for all tests and read by two blinded trained evaluators.

RESULTS

We evaluated 120, 80, 90, and 90 samples, respectively. Specificity for both IgM and IgG was 100% for the first two tests (95% confidence intervals [CI] 97.0-100 and 95.5-100, respectively). The third test had a specificity of 98.9% (95% CI 94.0-100) for IgM and 94.4% (95% CI 87.5-98.2) for IgG. The fourth test had a specificity of 88.9% (95% CI 80.5-94.5) for IgM and 100% (95% CI 96.0-100) for IgG.

DISCUSSION

COVID-19 serologic rapid tests are of variable specificity. Blood specimens from sentinel prenatal clinics provide an opportunity to validate serologic tests with population-based samples.

SARS-CoV-2 testing for asymptomatic adult cancer patients before initiating systemic treatments: a systematic review

Introduction

Cancer patients may have a higher risk of severe events and unfavourable outcomes in the setting of COVID-19. This review addresses the question of whether to test asymptomatic cancer patients before initiating systemic cancer treatments.

Methods

This systematic review was conducted based on the PRISMA framework. Pubmed, Embase, Web of Science and Cochrane Central Register of Controlled Trials were systematically searched, as well as guidelines from international institutions involved in cancer care and COVID-19 research. Studies published in English, from 1 December 2019 to 27 May 2020 were considered eligible. We included studies which mentioned testing strategies for SARS-CoV-2 of asymptomatic cancer patients before starting immunosuppressive treatments.

Results

We identified 1,163 studies and 4 guidelines through the literature search. A total of 18 articles were considered eligible and were included in the final analysis. Two articles were cohort studies, and the remaining were expert consensuses and published guidelines. The most common recommendation among the studies in this systematic review was to test asymptomatic patients for SARS-CoV-2 prior to treatment.

Conclusion

There is a lack of studies which directly address COVID-19 testing of asymptomatic patients before treatment. Our systematic review showed that most of the published data favours routine test for SARS-CoV-2 before initiating systemic treatment but failed to identify a good level of evidence to support these recommendations. Based upon this review, we proposed local recommendations at our centre. Each institution should consider the pros and cons of testing asymptomatic patients, evaluating accessibility to testing resources and local epidemiology.

Urgent/emergency surgery during COVID-19 state of emergency in Portugal: a retrospective and observational study

Background

SARS-CoV-2 virus changed society's behaviour. Population was advised to reduce unnecessary heath care use to accommodate urgent cases and daily increase of COVID-19 patients. Health care facilities faced huge challenges, having to readjust their response to preserve good quality of care. In Portugal, a significant reduction in the number of admissions to the Emergency Department (ED) was reported all over the country, however the impact on the dynamics of undeferrable surgery remains to be reported. This study compares the volume and characteristics of urgent/emergency surgery during the 2020 COVID-19 pandemic with the homologous period in 2019, chronologically illustrating the national evolution of new COVID-19 cases and the social and hospital containment response.

Methods

A retrospective observational study was conducted in a tertiary hospital center located in the most affected region by COVID-19 in Portugal. Medical records of patients who underwent urgent/emergency surgery between March 1^st and May 2^nd of both 2020 and 2019 were examined and the volume of surgeries were compared. Also, daily national updates from Portuguese Directorate-General for Health were analysed.

Results

During the COVID-19 pandemic approximately 30% less patients underwent urgent/emergency surgery (99%CI = 0.18-0.61, p < 0.001). Waiting time for surgery showed no difference between both years (p = 0.068), but patients who did surgery during the 2020 pandemic had higher mortality rates than the ones who did it in 2019 (11.4% in 2020 and 5.9% in 2019, p = 0.001). Reduction in surgery volume was correlated with the increasing number of infected cases nationally.

Conclusion

This study demonstrates decreasing numbers of urgent/emergency procedures during the COVID-19 pandemic that may be justified by the national growth number of infected cases. Preoperative mass screening strategy was implemented without compromising the efficiency of surgical service, but patients' mortality was higher. The importance of visiting the ED during COVID-19 pandemic for serious cases that cannot be managed in other settings should be highlighted.

Accessibility to SARS-CoV-2 swab test during the Covid-19 pandemic: Did age make the difference?

Although COVID-19 affects older people more severely, health policies during the first wave of the pandemic often prioritized younger individuals. We investigated whether age had influenced the access to a diagnostic test for SARS-CoV-2 infection and whether clinical complexity and healthcare resources availability could have impacted such differences. This work included 126,741 Italian participants in the EPICOVID19 web-based survey, who reported having had contacts with known/suspected COVID-19 cases (epidemiological criterion) and/or COVID-19-like signs/symptoms (clinical criterion) from February to June 2020. Data on sociodemographic, medical history and access to SARS-CoV-2 nasopharyngeal swab (NPS) were collected. Logistic regressions estimated the probability of accessing NPS as a function of age and the possible modifying effect of chronic diseases' number and residential areas in such association. A total of 6136 (4.8%) participants had undergone an NPS. Older participants had lower NPS frequencies than the younger ones when reporting epidemiological (14.9% vs. 8.8%) or both epidemiological and clinical criteria (17.5% vs. 13.7%). After adjustment for potential confounders, including epidemiological and clinical criteria, the chance of NPS access decreased by 29% (OR=0.71, 95%CI:0.63-0.79) in older vs. younger individuals. Such disparity was accentuated in areas with greater healthcare resources. In conclusion, in the first wave of the pandemic, age may have affected the access to COVID-19 diagnostic testing, disadvantaging older people.

Saliva May Be Considered as Reliable Tool for Diagnosis of COVID-19 When Compared With Nasopharynx or Throat Swabs

Article Title and Bibliographic Information

Saliva in the Diagnosis of COVID-19: A Review and New Research Directions. Fernandes LL, Pacheco VB, Borges L et al. Journal of Dental Research. 2020. https://doi.org/10.1177/0022034520960070.

Source of Funding

10.13039/501100007698Hospital Israelita Albert Einstein and Universidade Cruzeiro do Sul, São Paulo, Brazil. The authors have no actual or potential conflicts of interest.

Type of Study/Design

Systematic review.