Low Prevalence Settings Research Articles

Comparative Performance of Latest-Generation and FDA-Cleared Serology Tests for the Diagnosis of Chagas Disease.

Confirmed diagnosis of chronic Chagas disease (CD) requires positive results by two different IgG serology tests. Variable sensitivity has been reported among tests and in different geographic regions. Inadequate specificity presents a particular challenge in low-prevalence settings such as the United States. This study provides a direct comparison of the latest-generation IgG serology assays with four previously assessed FDA-cleared tests. Seven hundred ten blood donor plasma specimens were evaluated by Wiener Lisado and Wiener v.4.0 enzyme-linked immunosorbent assays (ELISAs) and Abbott PRISM Chagas chemiluminescent assay (ChLIA). Sensitivity and specificity were assessed relative to infection status as determined by the original blood donation testing algorithm. All three latest-generation assays demonstrated 100% specificity (95% confidence interval [CI], 98.6 to 100.0). Wiener Lisado, Wiener v.4.0, and Abbott PRISM had sensitivities of 97.1% (95% CI, 95.1 to 98.4), 98.9% (95% CI, 97.4 to 99.6), and 95.5% (95% CI, 93.2 to 97.3), respectively. As with previously evaluated FDA-cleared tests, all three assays had the highest reactivity and sensitivity in samples from donors born in South America and lowest reactivity and sensitivity in specimens from those born in Mexico, with intermediate results in specimens from Central American donors. Wiener v.4.0 had the highest diagnostic sensitivity in all comparisons. Our findings suggest that the latest-generation CD serology tests could improve diagnostic sensitivity without affecting specificity.

Monitoring of hospital sewage shows both promise and limitations as an early-warning system for carbapenemase-producing Enterobacterales in a low-prevalence setting

Carbapenemase-producing Enterobacterales (CPE) constitute a significant threat to healthcare systems. Continuous surveillance is important for the management and early warning of these bacteria. Sewage monitoring has been suggested as a possible resource-efficient complement to traditional clinical surveillance. It should not least be suitable for rare forms of resistance since a single sewage sample contains bacteria from a large number of individuals. Here, the value of sewage monitoring in early warning of CPE was assessed at the Sahlgrenska University Hospital in Gothenburg, Sweden, a setting with low prevalence of CPE. Twenty composite hospital sewage samples were collected during a two-year period. Carbapenemase genes in the complex samples were analyzed by quantitative PCR and the CPE loads were assessed through cultures on CPE-selective agar followed by species determination as well as phenotypic and genotypic tests targeting carbapenemases of presumed CPE. The findings were related to CPE detected in hospitalized patients. A subset of CPE isolates from sewage and patients were subjected to whole genome sequencing. For three of the investigated carbapenemase genes, blaNDM, blaOXA-48-like and blaKPC, there was concordance between gene levels and abundance of corresponding CPE in sewage. For the other two analyzed genes, blaVIM and blaIMP, there was no such concordance, most likely due to the presence of those genes in non-Enterobacterales populating the sewage samples. In line with the detection of OXA-48-like- and NDM-producing CPE in sewage, these were also the most commonly detected CPE in patients. NDM-producing CPE were detected on a single occasion in sewage and isolated strains were shown to match strains detected in a patient. A marked peak in CPE producing OXA-48-like enzymes was observed in sewage during a few months. When levels started to increase there were no known cases of such CPE at the hospital but soon after a few cases were detected in samples from patients. The OXA-48-like-producing CPE from sewage and patients represented different strains, but they carried similar blaOXA-48-like-harbouring mobile genetic elements. In conclusion, sewage analyses show both promise and limitations as a complement to traditional clinical resistance surveillance for early warning of rare forms of resistance. Further evaluation and careful interpretation are needed to fully assess the value of such a sewage monitoring system.

The impact of mass drug administration expansion to low onchocerciasis prevalence settings in case of connected villages.

The existence of locations with low but stable onchocerciasis prevalence is not well understood. An often suggested yet poorly investigated explanation is that the infection spills over from neighbouring locations with higher infection densities. We adapted the stochastic individual based model ONCHOSIM to enable the simulation of multiple villages, with separate blackfly (intermediate host) and human populations, which are connected through the regular movement of the villagers and/or the flies. With this model we explore the impact of the type, direction and degree of connectedness, and of the impact of localized or full-area mass drug administration (MDA) over a range of connected village settings. In settings with annual fly biting rates (ABR) below the threshold needed for stable local transmission, persistence of onchocerciasis prevalence can well be explained by regular human traffic and/or fly movement from locations with higher ABR. Elimination of onchocerciasis will then theoretically be reached by only implementing MDA in the higher prevalence area, although lingering infection in the low prevalence location can trigger resurgence of transmission in the total region when MDA is stopped too soon. Expanding MDA implementation to the lower ABR location can therefore shorten the duration of MDA needed. For example, when prevalence spill-over is due to human traffic, and both locations have about equal populations, then the MDA duration can be shortened by up to three years. If the lower ABR location has twice as many inhabitants, the reduction can even be up to six years, but if spill-over is due to fly movement, the expected reduction is less than a year. Although MDA implementation might not always be necessary in locations with stable low onchocerciasis prevalence, in many circumstances it is recommended to accelerate achieving elimination in the wider area.

Balancing HIV testing efficiency with HIV case-identification among children and adolescents (2-19 years) using an HIV risk screening approach in Tanzania.

To optimize HIV testing resources, programs are moving away from universal testing strategies toward a risk-based screening approach to testing children/adolescents, but there is little consensus around what defines an optimal risk screening tool. This study aimed to validate a 12-item risk screening tool among children and adolescents and provide suggested fewer-item tool options for screening both facility out-patient and community populations by age strata (<10 and ≥10 years). Children/adolescents (2–19 years) with unknown HIV status were recruited from a community-based vulnerable children program and health facilities in 5 regions of Tanzania in 2019. Lay workers administered the screening questions to caregivers/adolescents; nurses enrolled those eligible for the study and tested all participants for HIV. For each screening item, we estimated sensitivity, specificity, positive predictive value and negative predictive value and associated 95% confidence intervals (CI). We generated a score based on the count of items with a positive risk response and fit a receiver operating characteristic curve to determine a cut-off score. Sensitivity, specificity, positive predictive value (PPV; yield) and number needed to test to detect an HIV-positive child (NNT) were estimated for various tool options by age group. We enrolled 21,008 children and adolescents. The proportion of undiagnosed HIV-positive children was low (n = 76; 0.36%; CI:0.29,0.45%). A screening algorithm based on reporting at least one or more items on the 10 to 12-item tool had sensitivity 89.2% (CI:79.1,95.6), specificity 37.5% (CI:36.8,38.2), positive predictive value 0.5% (CI:0.4,0.6) and NNT = 211. An algorithm based on at least two or more items resulted in lower sensitivity (64.6%), improved specificity (69.1%), PPV (0.7%) and NNT = 145. A shorter tool derived from the 10 to 12-item screening tool with a score of “1” or more on the following items: relative died, ever hospitalized, cough, family member with HIV, and sexually active if 10–19 years performed optimally with 85.3% (CI:74.6,92.7) sensitivity, 44.2% (CI:43.5,44.9) specificity, 0.5% (CI:0.4,0.7) PPV and NNT = 193. We propose that different short-tool options (3–5 items) can achieve an optimal balance between reduced HIV testing costs (lower NNT) with acceptable sensitivity. In low prevalence settings, changes in yield may be negligible and NNT may remain high even for an effective tool.

Epidemiological evaluation of sewage surveillance as a tool to detect the presence of COVID-19 cases in a low case load setting

In low prevalence settings the development of sensitive and specific quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) tests to detect SARS-CoV-2 (the virus causing COVID-19) in sewage presents the possibility of using sewage sampling as a diagnostic test for the presence of infected people in the catchment of the sampled sewer. However, the usefulness of such surveillance has not been quantified. In this study in the Australian state of Victoria between August and October 2020 the location of each known SARS-CoV-2-infected person was determined on each day from two days before onset to 55 days after, in 46 metropolitan and rural sewer catchments sampled weekly – a total of 71 positive and 275 negative samples, and 354,155 person-days of location data. These were categorised by time since onset and distance from the sampling site. The odds of detection in sewage were between 5 and 20 times higher where known cases were present, with less effect of distance than time since onset. Using positive qRT-PCR in a sewage sample as a diagnostic test not just for viral RNA in the sample, but for the presence of known infected people in the catchment on the same day, the sensitivity was moderate (31% to 76%) and the specificity high (87% to 94%). The odds of detection were increased with increased numbers of known infected people but decreased with increased distance and time since onset. The probability of detection of the viral subgenome in sewage samples was about 10% when one known infected person was present, and this increased with higher numbers of known infected people and greater proximity to the sampling site. Sewage surveillance can be used to detect people infected with SARS-CoV-2 in the catchment, directing a search for infectious clinical cases and other public health actions. However, detection at least eight weeks after onset may be due to existing cases rather than new ones, and, although not zero, the probability of detecting a single case is low.

Validation testing to determine the sensitivity of lateral flow testing for asymptomatic SARS-CoV-2 detection in low prevalence settings: Testing frequency and public health messaging is key.

Lateral flow devices (LFDs) are quickly being implemented for use in large-scale population surveillance programs for SARS-CoV-2 infection in the United Kingdom. These programs have been piloted in city-wide screening in the city of Liverpool and are now being rolled out to support care home visits and the return home of University students for the Christmas break. Here, we present data on the performance of LFDs to test almost 8,000 students at the University of Birmingham between December 2 and December 9, 2020. The performance is validated against almost 800 samples using PCR performed in the University Pillar 2 testing lab and theoretically validated on thousands of Pillar 2 PCR testing results performed on low-prevalence care home testing samples. Our data show that LFDs do not detect infections presenting with PCR Ct values over 29 to 30 as determined using the Thermo Fisher TaqPath asssay. This may be of particular importance in detecting individuals that are either at the early, or late stages of infection, and reinforces the need for frequent, recurrent testing.

A comprehensive antigen production and characterisation study for easy-to-implement, specific and quantitative SARS-CoV-2 serotests.

BackgroundAntibody tests are essential tools to investigate humoral immunity following SARS-CoV-2 infection or vaccination. While first-generation antibody tests have primarily provided qualitative results, accurate seroprevalence studies and tracking of antibody levels over time require highly specific, sensitive and quantitative test setups.MethodsWe have developed two quantitative, easy-to-implement SARS-CoV-2 antibody tests, based on the spike receptor binding domain and the nucleocapsid protein. Comprehensive evaluation of antigens from several biotechnological platforms enabled the identification of superior antigen designs for reliable serodiagnostic. Cut-off modelling based on unprecedented large and heterogeneous multicentric validation cohorts allowed us to define optimal thresholds for the tests’ broad applications in different aspects of clinical use, such as seroprevalence studies and convalescent plasma donor qualification.FindingsBoth developed serotests individually performed similarly-well as fully-automated CE-marked test systems. Our described sensitivity-improved orthogonal test approach assures highest specificity (99.8%); thereby enabling robust serodiagnosis in low-prevalence settings with simple test formats. The inclusion of a calibrator permits accurate quantitative monitoring of antibody concentrations in samples collected at different time points during the acute and convalescent phase of COVID-19 and disclosed antibody level thresholds that correlate well with robust neutralization of authentic SARS-CoV-2 virus.InterpretationWe demonstrate that antigen source and purity strongly impact serotest performance. Comprehensive biotechnology-assisted selection of antigens and in-depth characterisation of the assays allowed us to overcome limitations of simple ELISA-based antibody test formats based on chromometric reporters, to yield comparable assay performance as fully-automated platforms.FundingWWTF, Project No. COV20–016; BOKU, LBI/LBG

Seroprevalence of severe acute respiratory syndrome coronavirus 2 in Slovenia: results of two rounds of a nationwide population study on a probability-based sample, challenges and lessons learned

ObjectivesSeroprevalence surveys provide crucial information on cumulative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure. This Slovenian nationwide population study is the first longitudinal 6-month serosurvey using probability-based samples across all age categories. MethodsEach participant supplied two blood samples: 1316 samples in April 2020 (first round) and 1211 in October/November 2020 (second round). The first-round sera were tested using Euroimmun Anti-SARS-CoV-2 ELISA IgG (ELISA) and, because of uncertain estimates, were retested using Elecsys Anti-SARS-CoV-2 (Elecsys-N) and Elecsys Anti-SARS-CoV-2 S (Elecsys-S). The second-round sera were concomitantly tested using Elecsys-N/Elecsys-S. ResultsThe populations of both rounds matched the overall population (n = 3000), with minor settlement type and age differences. The first-round seroprevalence corrected for the ELISA manufacturer's specificity was 2.78% (95% highest density interval [HDI] 1.81%–3.80%), corrected using pooled ELISA specificity calculated from published data 0.93% (95% CI 0.00%–2.65%), and based on Elecsys-N/Elecsys-S results 0.87% (95% HDI 0.40%–1.38%). The second-round unadjusted lower limit of seroprevalence on 11 November 2020 was 4.06% (95% HDI 2.97%–5.16%) and on 3 October 2020, unadjusted upper limit was 4.29% (95% HDI 3.18%–5.47%). ConclusionsSARS-CoV-2 seroprevalence in Slovenia increased four-fold from late April to October/November 2020, mainly due to a devastating second wave. Significant logistic/methodological challenges accompanied both rounds. The main lessons learned were a need for caution when relying on manufacturer-generated assay evaluation data, the importance of multiple manufacturer-independent assay performance assessments, the need for concomitant use of highly-specific serological assays targeting different SARS-CoV-2 proteins in serosurveys conducted in low-prevalence settings or during epidemic exponential growth and the usefulness of a Bayesian approach for overcoming complex methodological challenges.

Chorea as the presenting feature of acute rheumatic fever in childhood; case reports from a low-prevalence European setting

BackgroundDespite a notable decrease in acute rheumatic fever (ARF) incidence in the past few decades, there are still cases in our setting. Sydenham chorea (SC) may be the initial manifestation for this condition in childhood in a significant proportion of children. We report two cases of choreoathetosis in children as the first manifestation of ARF.Case presentationA previously healthy 8-year-old boy presented with right hemichorea with a predominance in the brachial region, orofacial dyskinesias and speech difficulties for the past 2 weeks. The only medical history of interest was a common catarrhal illness 3 weeks before and nonspecific bilateral tenosynovitis in both feet since a year prior. A brain computerized tomography was normal and the echocardiogram showed mild mitral and aortic regurgitation, meeting ARF criteria. He demonstrated clinical improvement with treatment based on prednisone and carbamazepine.The second patient was a 10-year-old girl with choreic movements of the right half of the body and repetitive right eye closure of 1 week duration. She had symptoms of fever and rash the previous week and pharyngitis that resolved without antibiotic 2 months before. Blood tests revealed elevated C reactive protein (12 mg/dl) and erythrocyte sedimentation rate (96 mm/h). Brain magnetic resonance was normal and echocardiogram showed left ventricle dilation and mild mitral regurgitation, leading to the diagnosis of ARF. Due to neurological involvement, she received corticosteroids and intravenous immunoglobulin treatment, with worsening of neurological symptoms that required valproic acid with remission of the hemichorea. In addition skin lessions compatible with erythema marginatum appeared on the upper limbs.ConclusionsSC should be the main diagnostic consideration in cases of hemichorea with normal neuroimaging in children. The cases reported highlight the need to maintain a high index of suspicion even in settings where incidende of ARF is low and the need to perform cardiological investigations in all patients with suspected SC, due to the possibility of subclinical valve lesions. Good adherence to secondary prophylaxis is crucial to avoid chorea relapses and worsening valve disease.

Medication adherence and complementary therapy usage in inflammatory bowel disease patients during the coronavirus disease 2019 pandemic.

Background and AimMedication nonadherence is common in patients with inflammatory bowel disease (IBD) and has been associated with worse outcomes. The coronavirus disease 2019 (COVID‐19) pandemic led to significant consumer and medical concern regarding the possible risks of immunosuppressive medications during the pandemic. This study aimed to examine medication adherence and complementary and alternative medicine (CAM) usage during the COVID‐19 pandemic.MethodsAn online survey was sent to patients from two tertiary IBD units. The survey included medication nonadherence attributed to the COVID‐19 pandemic, complementary therapy, and IBD medication use. Validated measures of IBD disease activity, medication adherence, and beliefs about medicines were obtained.ResultsOf 262 respondents (median age of 46, 58% female) 14 (5%) patients reported self‐initiated missed doses or dose reduction of IBD medications directly attributed to the COVID‐19 pandemic. Positive associations with medication nonadherence included current corticosteroid requirement (P = 0.022), higher disease activity scores (P = 0.026), and higher concern about medicines score (P = 0.04). CAM usage was common, aimed at treating mental health in most cases, and infrequently attributed to the COVID‐19 pandemic.ConclusionsEven in the setting of low COVID‐19 prevalence, the pandemic reduced IBD medication adherence in 1 in 20 patients. This reduced adherence was co‐associated with increased disease activity and corticosteroid use. Understanding the underlying beliefs driving suboptimal IBD medication adherence is critical to prevent avoidable adverse IBD outcomes.

Rapid, point-of-care antigen and molecular-based tests for diagnosis of SARS-CoV-2 infection.

Rapid, point-of-care antigen and molecular-based tests for diagnosis of SARS-CoV-2 infection.

Serological Evaluation of Human Antibodies of the Immunoglobulin Class A and G Against SARS-CoV-2 in Serum Collected in Newfoundland and Labrador.

The ability to detect antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently under investigation with various performance characteristics and indications for use. In this article, we analyzed the ability of the Abbott SARS-CoV-2 immunoglobulin class G (IgG), EuroImmun SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) IgG, and EuroImmun SARS-CoV-2 ELISA immunoglobulin class A (IgA) kits to detect evidence of previous infection with SARS-CoV-2. We tested 49 known coronavirus disease-19 (COVID-19) patients and 111 prepandemic stored serology specimens. This resulted in a sensitivity of 95.9%, 100.0%, and 91.3% and a specificity of 98.2%, 98.2%, and 90.8% respectively, using manufacturer recommended cutoffs after inconclusive results (one for EuroImmun IgG and five for EuroImmun IgA) being excluded in the final statistical analyses. Cross-reactivity of hepatitis C virus seropositive specimens was observed resulting in false positives (p < 0.05). If a two-tiered algorithmic approach was applied, that is, testing with Abbott SARS-CoV-2 assay followed by EuroImmun SARS-CoV-2 IgG, 100% specificity and sensitivity could be obtained after six inconclusive results were excluded from data set before statistical analyses. Performance characteristics presented demonstrate the superior performance of IgG class antibodies for investigating previous infections. In addition, utilizing a second antibody test for supplementary testing may significantly enhance performance, particularly in lower prevalence settings.

Multi-site assessment of rapid, point-of-care antigen testing for the diagnosis of SARS-CoV-2 infection in a low-prevalence setting: A validation and implementation study

BackgroundIn Australia, COVID-19 diagnosis relies on RT-PCR testing which is relatively costly and time-consuming. To date, few studies have assessed the performance and implementation of rapid antigen-based SARS-CoV-2 testing in a setting with a low prevalence of COVID-19 infections, such as Australia. MethodsThis study recruited participants presenting for COVID-19 testing at three Melbourne metropolitan hospitals during a period of low COVID-19 prevalence. The Abbott PanBioTM COVID-19 Ag point-of-care test was performed alongside RT-PCR. In addition, participants with COVID-19 notified to the Victorian Government were invited to provide additional swabs to aid validation. Implementation challenges were also documented. FindingsThe specificity of the Abbott PanBioTM COVID-19 Ag test was 99.96% (95% CI 99.73 - 100%). Sensitivity amongst participants with RT-PCR-confirmed infection was dependent upon the duration of symptoms reported, ranging from 77.3% (duration 1 to 33 days) to 100% in those within seven days of symptom onset. A range of implementation challenges were identified which may inform future COVID-19 testing strategies in a low prevalence setting. InterpretationGiven the high specificity, antigen-based tests may be most useful in rapidly triaging public health and hospital resources while expediting confirmatory RT-PCR testing. Considering the limitations in test sensitivity and the potential for rapid transmission in susceptible populations, particularly in hospital settings, careful consideration is required for implementation of antigen testing in a low prevalence setting. FundingThis work was funded by the Victorian Department of Health and Human Services. The funder was not involved in data analysis or manuscript preparation.

SARS-CoV-2 transmissions in students and teachers: seroprevalence follow-up study in a German secondary school in November and December 2020

ObjectiveTo quantify the number of undetected SARS-CoV-2 infections in educational settings.DesignSerial SARS-CoV-2 seroprevalence study before and during the second wave of the COVID-19 pandemic.SettingSecondary school in Dresden, Germany.ParticipantsGrade 8–12 students...

Different diagnostic strategies for different settings

Diagnostic strategies should always take into consideration the setting in which they are administered. The predictive value, positive or negative of a clinical sign or diagnostic test has a different weight in family medicine than in the hospital setting. Many tests have not been formally evaluated in primary care; unfortunately, very often low prevalence settings are used to conduct screening in these populations, and often result in unrealistically high prevalence estimates for chronic disease and these results are then used to conclude that General Practitioners are not good at detecting diseases. In primary care, the prevalence and incidence of disease differs from what appears in the hospital setting, and severe disease occurs less frequently in general practice than in hospital because there is no preventive selection. This requires a specific probability-based decision-making process, based by the knowledge of patients and the community. In primary care, the diagnostic strategy should begin with complaints and symptoms and address uncertainty and complexity, using step-by-step strategies, including watchful waiting, presumptive symptomatic treatment, and focusing on low-tech strategies.

DETECT Schools Study Protocol: A Prospective Observational Cohort Surveillance Study Investigating the Impact of COVID-19 in Western Australian Schools.

Introduction: Amidst the evolving COVID-19 pandemic, understanding the transmission dynamics of the SARS-CoV-2 virus is key to providing peace of mind for the community and informing policy-making decisions. While available data suggest that school-aged children are not significant spreaders of SARS-CoV-2, the possibility of transmission in schools remains an ongoing concern, especially among an aging teaching workforce. Even in low-prevalence settings, communities must balance the potential risk of transmission with the need for students' ongoing education. Through the roll out of high-throughput school-based SARS-CoV-2 testing, enhanced follow-up for individuals exposed to COVID-19 and wellbeing surveys, this study investigates the dynamics of SARS-CoV-2 transmission and the current psychosocial wellbeing impacts of the pandemic in school communities.Methods: The DETECT Schools Study is a prospective observational cohort surveillance study in 79 schools across Western Australia (WA), Australia. To investigate the incidence, transmission and impact of SARS-CoV-2 in schools, the study comprises three “modules”: Module 1) Spot-testing in schools to screen for asymptomatic SARS-CoV-2; Module 2) Enhanced surveillance of close contacts following the identification of any COVID-19 case to determine the secondary attack rate of SARS-CoV-2 in a school setting; and Module 3) Survey monitoring of school staff, students and their parents to assess psycho-social wellbeing following the first wave of the COVID-19 pandemic in WA.Clinical Trial Registration: Trial registration number: ACTRN12620000922976

Androgen deprivation therapy and risk of SARS-CoV-2 infection in men with prostate cancer: A University of California (UC) Health System registry study.

37 Background: SARS-CoV-2 entry into host cells is facilitated by the transmembrane protease TMPRSS2. TMPRSS2 expression can be modulated by the androgen receptor. It is unclear whether androgen deprivation therapy (ADT) may partially protect from SARS-CoV-2 infection. Methods: A retrospective registry study of adult men with prostate cancer who underwent testing for SARS-CoV-2 in the UC Health System between February 1, 2020 and October 6, 2020 was performed. The University of California Health COVID Research Data Set (UC CORDS), which includes electronic health data of all patients who underwent testing for SARS-CoV-2 at 5 UC academic medical centers (UC Davis, UC Irvine, UC Los Angeles, UC San Diego, and UC San Francisco) and 12 affiliated hospitals across California, was used. Association of SARS-CoV-2 infection and receipt of ADT (GnRH agonist or antagonist) within 90 days of COVID testing was determined using the Chi-Squared test. Analyses (Chi-Squared or Fisher’s exact tests) were also performed in race/ethnicity subgroups. Results: Overall, 2,948 men with prostate cancer who underwent SARS-CoV-2 testing were identified, of whom 59 (2.0%) tested positive. Of the 2,948 men, 2,124 (72%) were White; 219 (7%) Black or African-American; 182 (6%) Asian or Native Hawaiian/Pacific-Islander; 176 (6%) Other race; and 247 (8%) Unknown race. There were 235 (8%) Hispanic or Latino men. Among the 444 men who received ADT in the entire cohort, 7 (1.6%) tested positive, and among the 2,504 men who did not receive ADT, 52 (2.1%) tested positive (OR 0.76, 95% CI 0.34-1.67, P = 0.49). No statistically significant association between ADT and SARS-CoV-2 positivity was found within race or ethnicity subgroups. Conclusions: No association between the use of ADT and the risk of testing positive for SARS-CoV-2 was identified in this study of a diverse patient population in the University of California Health System medical centers and hospitals. In this setting of an overall low prevalence of SARS-CoV-2 infection, thus far, there is no strong evidence of a protective benefit of ADT.

Use of Helicopter Emergency Medical Services in the Transport of Patients With Known or Suspected Coronavirus Disease 2019

ObjectiveLimited information exists regarding the response of helicopter emergency medical services (HEMS) programs to patients with known or suspected coronavirus disease 2019 (COVID-19). The purpose of this study was to determine changes in flight operations during the early stages of the pandemic. MethodsA survey of the American College of Emergency Physicians Air Medical Section was conducted between May 13, 2020, and August 1, 2020. COVID-19 prevalence was defined as high versus low based on cases > 2,500 or ≤ 2,500. ResultsOf the 48 respondents, the majority (89.6%) reported that their patient guidelines had changed because of COVID-19; 89.6% of programs reported transporting COVID-19–positive patients, whereas 91.5% reported transporting persons under investigation. The majority of respondents reported additional training in COVID-19 airway management (79.2%) and personal protective equipment use (93.6%). Permitted aerosol-generating procedures included bilevel positive airway pressure (40.4%) and high-flow nasal oxygen (66.0%). No difference in guideline changes, positive COVID-19/persons under investigation transport restrictions, or permitted aerosol-generating procedures were noted between high- and low-prevalence settings. ConclusionCOVID-19 has resulted in changes to HEMS guidelines regardless of local disease prevalence. The pandemic has persisted sufficiently long that data regarding the effectiveness of guideline changes should be analyzed. In the absence of definitive data, national best practices should be developed to guide COVID-19 HEMS transport.

Latent Class Analysis: Insights about design and analysis of schistosomiasis diagnostic studies.

Various global health initiatives are currently advocating the elimination of schistosomiasis within the next decade. Schistosomiasis is a highly debilitating tropical infectious disease with severe burden of morbidity and thus operational research accurately evaluating diagnostics that quantify the epidemic status for guiding effective strategies is essential. Latent class models (LCMs) have been generally considered in epidemiology and in particular in recent schistosomiasis diagnostic studies as a flexible tool for evaluating diagnostics because assessing the true infection status (via a gold standard) is not possible. However, within the biostatistics literature, classical LCM have already been criticised for real-life problems under violation of the conditional independence (CI) assumption and when applied to a small number of diagnostics (i.e. most often 3-5 diagnostic tests). Solutions of relaxing the CI assumption and accounting for zero-inflation, as well as collecting partial gold standard information, have been proposed, offering the potential for more robust model estimates. In the current article, we examined such approaches in the context of schistosomiasis via analysis of two real datasets and extensive simulation studies. Our main conclusions highlighted poor model fit in low prevalence settings and the necessity of collecting partial gold standard information in such settings in order to improve the accuracy and reduce bias of sensitivity and specificity estimates.

Prevalence of SARS-CoV-2-Specific Antibodies, Japan, June 2020.

We used 2 commercially available antibody tests to estimate seroprevalence of severe acute respiratory syndrome coronavirus 2 infection in Japan during June 2020. Of 7,950 samples, 8 were positive by both assays. Using 2 reliable antibody tests in conjunction is an effective method for estimating seroprevalence in low prevalence settings.