Diagnostic Microbiology and Infectious Disease

BackgroundThe COVID-19 pandemic has been characterized by ongoing evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with concomitant variation in viral transmissibility and morbidity. Within specific timeframes and geographic areas, multiple SARS-CoV-2 variants have coexisted in the human population, each characterized by distinct biologic and clinical features, such as varying susceptibility to neutralizing monoclonal antibodies (nMAbs), a major frontline treatment. As part of an observational real-world data study of the effectiveness of nMAbs for treatment of COVID-19, SARS-CoV-2 viral samples were obtained from patients under treatment, generating paired clinical and genomics data. This paper describes the processing pipeline and findings from the genomics portion of this combined data set. MethodsSARS-CoV-2 sequences were generated from 14,796 diagnostic samples from four large U.S. health systems between July 2020 and March 2022. Among nMAbs-treated patients, samples were collected on the same day as, or prior to, treatment with nMAbs. Thus, these samples represent a snapshot of SARS-CoV-2 variants circulating in the respective patient groups, as opposed to variants that arose in response to specific treatments. Health systems collected viral samples and performed library creation and sequencing according to local protocols, using tiled ARTIC amplicon primers. FASTQ files were submitted to a study data platform and processed through a common pipeline. This pipeline enabled a unified approach to quality control, assembly, and production of genomics features for downstream analysis. ResultsAlpha and pre-Alpha SARS-CoV-2 lineages were predominant in the data set prior to June 2021. From June 2021 through November 2021, Delta was the dominant variant. Beginning in December 2021, Omicron was dominant. A variety of mutations associated with decreased nMAbs binding to the spike protein in vitro were detected, including lineage-defining mutations and non-lineage-defining mutations such as E340A, G446V, and S494P. Distinct patterns of sequence gaps and ambiguous base calls were associated with distinct variants. ConclusionsThe distribution of SARS-CoV-2 variants, per WHO nomenclature, across epochs in this data set matched concurrent CDC genomic surveillance results across the U.S. Detection of putative nMAbs escape mutations within clinical samples was consistent with FDA decisions to amend EUAs as variants emerged. This genomics data set provides an opportunity to examine associations between SARS-CoV-2 genomic variation and clinical outcomes in the associated EHR data set. The expansion of real-world data sets such as this to study the relationship between viral sequence and treatment outcomes could provide the foundation for future efforts to achieve near-real-time understanding of clinical outcomes related to genomic variation over time, and evidence to update treatment decisions more rapidly and to greater effect during ongoing and future pandemics.

The emergence of new SARS-CoV-2 variants necessitates the reevaluation of current COVID-19 tests to ensure continued accuracy and reliability. The new SARS-CoV-2 variant, Omicron, is heavily mutated, with over 50 mutations within its RNA genome. Any of these mutations could adversely affect the ability of diagnostic assays to detect the virus in patient samples, potentially leading to inconclusive or false negative results. In fact, the U.S. Food and Drug Administration (FDA) has identified over two dozen diagnostic tests that contain a gene target that is expected to have "significantly reduced sensitivity due to a mutation in the SAS-CoV-2 Omicron variant"1. Additionally, one of the U.S. Centers for Disease Control and Prevention (CDC) Emergency Use Authorization (EUA) targets for COVID-19 tests, 2019-nCoV_N1, overlaps an Omicron mutation within the sequence targeted by the fluorescent probe. This target from the CDC has been used in many other EUA assays. Using in vitro transcribed (IVT) N gene RNA representing the wild-type (GenBank/GISAID ID MN908947.3) and Omicron variant (BA.1, GISAID ID EPI_ISL_6752027), we evaluated the performance of two different amplification protocols, both of which include the CDC 2019-nCoV_N1 primer-probe set. Both assays were able to detect the mutant N1 sequence as efficiently as the wild-type sequence. Consequently, these data suggest that diagnostic assays that use the 2019-nCoV-N1 primer-probe set are unlikely to be impacted by currently circulating Omicron lineage viruses.

Concomitant infection of multiple SARS-CoV-2 variants has become an increasing concern, as this scenario increases the likelihood of recombinant variants. Detecting co-infection of SARS-CoV-2 variants is difficult to detect by whole genome sequencing approaches, but genotyping methods facilitate detection. We describe 2 cases of Delta/Omicron and 2 cases of Omicron sublineage BA.1/ BA.2 co-infection as detected by a multiplex genotyping fragment analysis method. Findings were confirmed by whole genome sequencing. Review of the patient characteristics revealed co-morbidities and conditions which weaken the immune system and may make them more susceptible to harboring SARS-CoV-2 variant co-infections.

Rapid classification and detection of SARS-CoV-2 variants have been critical in comprehending the viruss transmission dynamics. Clinical manifestation of the infection is influenced by comorbidities such as age, immune status, diabetes, and the infecting variant. Thus, clinical management may differ for new variants. For example, some monoclonal antibody treatments are variant-specific. Yet, an FDA-approved test for detecting the SARS-CoV-2 variant is unavailable. A laboratory-developed test (LDT) remains a viable option for reporting the infecting variant for clinical intervention or epidemiological purposes. Accordingly, we have validated the Illumina COVID-Seq assay as an LDT according to the guidelines prescribed by the College of American Pathologists (CAP) and Clinical Laboratory Improvement Amendments (CLIA). The limit of detection (LOD) of this test is Ct<30 ([~]15 viral copies) and >200X genomic coverage, and the test is 100% specific in the detection of existing variants. The test demonstrated 100% precision in inter-day, intra-day, and intra-laboratory reproducibility studies. It is also 100% accurate, defined by reference strain testing and split sample testing with other CLIA laboratories. Advanta Genetics LDT COVID Seq has been reviewed by CAP inspectors and is under review by FDA for Emergency Use Authorization.

The emergence of coronavirus disease 2019 (COVID-19) has become a major global health crisis. Currently, diagnosis is based on molecular techniques, which detect the viral nucleic acids when present at detectable levels. The serum IgG response against SARS-CoV-2 was examined by using an ELISA-based assay. Serum samples, along with nasopharyngeal specimens were collected from various cohorts and analyzed by ELISA and rRT-PCR, respectively. A total of 167 serum samples were tested for serum IgG antibodies against SARS-CoV-2 in outpatient cohorts, 15 (8.9%) were positive by rRT-PCR and the remaining 152 (91%) were negative. We used these data to generate two different assay cutoffs for serum IgG assay and investigated percent concordance with rRT-PCR test results. The emergency department data revealed, out of 151 nasopharyngeal swabs, 4 (2.6%) were positive by rRT-PCR and 18 (11.9%) were positive for serum IgG assay. Among the 18 patients that were positive for serum IgG, 13 (72.2%) exhibited 1-3 symptoms of COVID-19 and 5 (27.7%) patients did not present with any COVID-19 related symptoms, per CDC criteria. All 4 (100%) patients that were positive by rRT-PCR had symptoms of COVID-19 disease. A longitudinal study from the inpatient population suggested there was a sharp increase in the serum IgG titers in 5 patients, a moderate increase in 1 patient and a plateau in 3 patients. Sero-prevalence of COVID-19 disease in pre-procedure patients was 5.5%. Our findings suggest serological tests can be used for appropriate patient triaging when performed as an adjunct to existing molecular testing.

This dual-center study evaluated the impact of artificial intelligence (AI) on urine culture turnaround times in Canadian diagnostic laboratories employing full microbiology laboratory automation. Data were collected before and after the implementation of PhenoMATRIX (PM), an AI-based software designed to support culture sorting and result interpretation. In both a low-volume tertiary care hospital and a high-volume community laboratory, PM reduced the time to final culture reporting, with decreases of approximately 1.5 hours and 3.9 hours, respectively. Implementation of PM+, which automatically releases defined results to patient charts, further improved turnaround time. These findings indicate that microbiology laboratories with full laboratory automation can achieve further improvements in turnaround time by integrating AI-culture assessment and results release.

The recent emergence of SARS-CoV-2 has lead to a global pandemic of unprecedented proportions. Current diagnosis of COVID-19 relies on the detection of SARS-CoV-2 RNA by RT-PCR in upper and lower respiratory specimens. While sensitive and specific, these RT-PCR assays require considerable supplies and reagents, which are often limited during global pandemics and surge testing. Here, we show that a nasopharyngeal swab pooling strategy can detect a single positive sample in pools of up to 10 samples without sacrificing RT-PCR sensitivity and specificity. We also report that this pooling strategy can be applied to rapid, moderate complexity assays, such as the BioFire COVID-19 test. Implementing a pooling strategy can significantly increase laboratory testing capacity while simultaneously reducing turnaround times for rapid identification and isolation of positive COVID-19 cases in high risk populations.

BackgroundThe increasing number of cases and hospital admissions due to COVID-19 created an urgent need for rapid, reliable testing procedures for SARS-CoV-2 in Emergency Departments (ED) in order to effectively manage hospital resources, allocate beds and prevent nosocomial spread of infection. The ID NOW COVID-19 assay is a simple, user-friendly, rapid molecular test run on an instrument with a small footprint enabling point-of-care diagnostics. MethodsIn the first wave, outsourced RT-PCR testing regularly required 36-48 hours before results were available. This prospective study was conducted in the second wave (October 2020-April 2021) and evaluated the impact the implementation of the ID NOW COVID-19 test in the ED had on clinical care processes and patient pathways. 710 patients were recruited upon arrival at the ED which included those presenting clinical symptoms, asymptomatic individuals or persons fulfilling epidemiological criteria. The first anterior nasal swab was taken by trained nurses in the ambulance or a separate consultation room. The ID NOW COVID-19 test was performed in the ED in strict compliance with the manufacturers instructions and positive or suspected cases were additionally tested with RT_PCR (cobas SARS-COV-2 RT-PCR, Roche) following collection of a second nasopharyngeal NP specimen. ResultsSwabs directly tested with the ID NOW COVID-19 test showed a diagnostic concordance of 98 % (sensitivity 99.59 %, specificity 94.55 %, PPV 97.6 %, NPV 99.05 %) compared to RT-PCR as reference. The 488 patients that tested positive with the ID NOW COVID-19 had a Ct range in RT-PCR results between 7.94 to 37.42 (in 23.2 % > 30). Two false negative results (0.28%) were recorded from patients with Ct values > 30. 14 (1.69%) discordant results were reviewed case-by-case and usually associated with either very early or very advanced stages of infection. Furthermore, patients initially negative with the ID NOW COVID-19 test and admitted to the hospital were tested again on days 5 and 12: no patient became positive. DiscussionThe ID NOW COVID-19 test for detection of SARS-CoV-2 demonstrated excellent diagnostic agreement with RT-PCR under the above-mentioned patients pathways implemented during the second wave. The main advantage of the system was the provision of reliable results within a few minutes. This not only allowed immediate initiative of appropriate therapy and care for COVID-19 (patient benefit) but provided essential information on isolation and thus available beds. This drastically helped the overall finances of the department and additionally allowed more patients to be admitted including those requiring immediate attention; this was not possible during the first wave since beds were blocked waiting for diagnostic confirmation. Our findings also show that when interpreting the results, the clinical condition and epidemiological history of the patient must be taken into account, as with any test procedure. Overall, the ID NOW COVID-19 test for SARS-CoV-2 provided a rapid and reliable alternative to laboratory-based RT-PCR in the real clinical setting which became an acceptable part of the daily routine within the ED and demonstrated that early patient management can mitigate the impact of the pandemic on the hospital.

Bronchoalveolar lavage samples (n=34) collected in February, 2020 prior to the wide availability of molecular testing for SARS-CoV-2 were retrospectively assayed for presence of viral RNA. None of these patients qualified for SARS-CoV-2 testing based on Centers for Disease Control criteria at the time. None of the samples tested positive for SARS-CoV-2, suggesting that the virus was not yet widespread in Minnesota at the time these samples were obtained.

ObjectiveThe FilmArray Blood Culture Identification (BCID) panel is a rapid microfluidic PCR amplification microbial detection system. Several studies have evaluated its clinical performance on the basis of blood culture bottles containing resins. However, proportion of hospitals in China use bottles with carbon power, which the performance of FilmArray has not been fully investigated. Therefore, this study is conducted to explore the accuracy of the panel using blood culture bottles with carbon power. Method147 venous blood cultures containing carbon powder were used to assess the microbial and antibiotic resistance detection ability of the FilmArray panel. Outcomes were compared with results of the clinical combination method and their consistency was analyzed. ResultsFilmArray detected single microorganism in 121 samples, multiple microorganism in 9 cases and the consistency rate between the two methods was 90.6%. Among the 150 microorganisms detected, 85.1% (40/47) of staphylococcus contained the antibiotic resistant mecA gene, 15.3% (9/59) of Enterobacter detected the KPC gene, 7.7% (1/13) of Enterococcus has the vanA gene and the consistency with their clinical drug-resistant phenotypes were 93.6%, 86.4% and 100%, respectively. ConclusionThe identification rate of the FilmArray BCID panel using venous blood cultures with activated carbon powder was highly consistent with the outcomes of previous researchers using non-carbon powder blood culture bottles. It is capable of providing rapid and reliable results in the detection of pathogens present in automated blood culture systems.

The emergence of the SARS-CoV-2 Omicron variant has motivated a re-evaluation of the test characteristics for lateral flow immunochromatographic assays (LFIAs), commonly referred to as rapid antigen tests. To address this need, we evaluated the analytic sensitivity of one of the most widely used LFIAs in the US market, the Abbott BinaxNOW COVID-19 Ag At-Home Card using 32 samples of Omicron and 30 samples of the Delta variant. Samples were chosen to intentionally over-represent the range of viral loads where differences are most likely to appear. We found no changes in the analytic sensitivity of the BinaxNOW assay by variant even after controlling for variation in cycle threshold values in the two populations. Similar to prior studies, the sensitivity of the assay is highly dependent on the amount of virus present in the sample. While the analytic sensitivity of the BinaxNOW LFIA remains intact versus the Omicron variant, its clinical sensitivity is influenced by the interaction between viral replication, the dynamics of tissue tropism and the timing of sampling. Further research is necessary to optimally adapt current testing strategies to robustly detect early infection by the Omicron variant to prevent transmission.

IntroductionSymptomatic and asymptomatic urinary tract infections (UTIs) are common. The Infectious Disease Society of America (IDSA) discourages testing and treating ASB other than in pregnant women during routine obstetric visit screening and patients undergoing urologic procedures with expected mucosal bleeding. Unnecessary urinalysis (UA) and inappropriate antibiotic use persist in Emergency Departments (EDs). This study aims to evaluate UA testing and antibiotic treatment patterns for ASB in an urban ED, assessing adherence to IDSA guidelines and setting baseline rates for an educational intervention to align testing and treatment with IDSA guidelines. MethodsWe conducted a 15-month study to assess adherence to IDSA guidelines for proper UTI screenings and prescribing. We reviewed records of 50 adult patients who had a UA at the Long Island Jewish Medical Center ED to determine whether they met IDSA criteria for UA testing and appropriate antibiotic use. Patients with sepsis or other conditions requiring empiric antibiotics were excluded. We performed a univariate analysis to describe the population and factors associated with treating urinalysis findings. Statistical significance was set at p <0.05. ResultsSixty-four percent of patients were asymptomatic and 36% were symptomatic. None of the asymptomatic patients met IDSA criteria for UA testing. Symptomatic patients were nearly-statistically more likely than asymptomatic patients to have a positive UA (72.2% vs. 43.8%, p = 0.06), and were more-often prescribed antibiotics for a positive UA (61.5% vs. 14.3%; p = 0.0128). They were also more-often prescribed antibiotics for a negative UA (20.0% vs. 0%; p = 0.05). DiscussionThe study findings revealed significant discordance between IDSA guidelines and current ED practices, with 64% of UA tests deemed unnecessary for ASB patients. These results align with previous studies highlighting the prevalence of over-testing with UAs and over-treatment of ASB. Unnecessary testing and inappropriate antibiotic treatment lead to increased costs and risks of antibiotic resistance, adverse drug events, and Clostridium difficile infection. This study highlights the necessity for planned educational initiatives to reduce unnecessary UAs and treatment and improve adherence to evidence-based guidelines.

IntroductionThe ongoing SARS-CoV-2 pandemic has spurred the development of numerous point of care (PoC) immunoassays. Assessments of performance of available kits are necessary to determine their clinical utility. Previous studies have mostly performed these assessments in a laboratory setting, which raises concerns of translating findings for PoC use. The aim of this study was to assess the performance of a lateral flow immunoassay for the detection of SARS-CoV-2 antibodies using samples collected at PoC. MethodOne lateral flow immunoassay (Humasis(R) COVID-19 IgG/IgM) was tested. In total, 50 PCR RT-PCR positive and 52 RT-PCR negative samples were collected at PoC. Fifty serum specimens from Dec 2018 to Feb 2019 were used as controls for specificity. Serum samples collected between Dec 2019 to Feb 2020 were used as additional comparators. Clinical data including symptom onset date was collected from patient history and the medical record. ResultsThe overall sensitivity for the kit was 74% (95% CI: 59.7% -85.4%). The sensitivity for IgM and IgG detection >14 days after date of onset was 88% (95% CI: 68.8% -97.5%) and 84% (95% CI: 63.9% - 95.5%), with a negative predictive value (NPV) of 94% for IgM (95% CI: 83.5% - 98.8%) and 93% for IgG (95% CI: 81.8% - 97.9%). The overall specificity was 94% (95% CI: 83.5% - 98.8%). The Immunoglobulin specific specificity was 94% for IgM (95% CI: 83.5% - 98.8%) and 98% for IgG (95% CI: 89.4% - 100.0%), with a positive predictive value (PPV) of 88% for IgM (95% CI: 68.8% - 97.5%) and 95% for IgG (95% CI: 77.2% - 99.9%) respectively for samples collected from patients >14 days after date of onset. Specimen collected during early phase of COVID-19 pandemic (Dec 2019 to Feb 2020) showed 11.8% antibody positivity, and 11.3% of PCR-negative patients demonstrated antibody positivity. DiscussionHumasis(R) COVID-19 IgG/IgM LFA demonstrates greater than 90% PPV and NPV for samples collected 14 days after the onset of symptoms using samples collected at PoC. While not practical for the diagnosis of acute infection, the use of the lateral flow assays with high specificity may have utility for determining seroprevalence or seroconversion in longitudinal studies.

We designed a multiplex qPCR to differentiate monkeypox virus clades. In evaluations using clinical samples collected in the UK and Nigeria, the assay had an overall sensitivity of 78% (95% CI: 67.67% to 86.14%) and specificity of 94% (95% CI: 80.84% to 99.30%); for samples under Ct35 sensitivity was 98% (95% CI: 91.72% to 99.96%) and specificity was 94% (95% CI: 80.84% to 99.30%).

Rapid classification and tracking of emerging SARS-CoV-2 variants are critical for understanding the transmission dynamics and developing strategies for interrupting the transmission chain. Next-Generation Sequencing (NGS) is an exceptional tool for whole-genome analysis and deciphering new mutations. The technique has been instrumental in identifying the Variants of Concern and tracking this pandemic. However, NGS remains expensive and time-consuming for large-scale monitoring of COVID-19. This study analyzed a total of 78 de-identified samples that screened positive for SARS-CoV-2 from two timeframes, August 2020 and July 2021. All 78 samples were classified into WHO lineages by whole genome sequencing then compared with two commercially available Q-PCR assays for spike protein mutation(s). The data showed good concordance with Q-PCR and NGS analysis for specific SARS-COV-2 lineages and characteristic mutations. Deployment of Q-PCR testing to detect known SARS-COV-2 variants may be extremely beneficial. These assays are quick and cost-effective, thus can be implemented as an alternative to sequencing for screening known mutations of SARS-COV-2 for clinical and epidemiological interest. The findings support the great potential for Q-PCR to be an effective strategy offering several COVID-19 epidemiological advantages.

IntroductionCoronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is diagnosed by molecular-based detection of SARS-CoV-2 RNA. Serologic testing detects antibodies specific to SARS-CoV-2 and IgM specifically may serve as an adjunct test to PCR early in disease. We evaluated the Abbott anti-SARS-CoV-2 IgM and IgG assays along with DiaSorin anti-SARS-CoV-2 IgG and Roche anti-SARS-CoV-2 Total. MethodsSpecimens from 175 PCR-positive patients and 107 control specimens were analyzed using Abbott IgM and IgG, DiaSorin IgG, and Roche Total (IgA, IgG, IgM) assays. Sensitivity, specificity, cross-reactivity, concordance between assays, trends over time, positive predictive value (PPV), and negative predictive value (NPV) were determined. ResultsAbbott IgM sensitivity was 63.6% at 0 days post-PCR positivity, 76.5% at 1-5d, 76.3% at 6-14d, 85.2% at 15-30d, and 63.6% at >30d. All assays exhibited highest sensitivity 15-30d post-PCR positivity (83.3-85.2%). Combining Abbott IgM and IgG improved sensitivity by 22.7% compared to IgG alone when tested 0d post-PCR positivity. All assays had a specificity of 100% and only Abbott IgG exhibited cross-reactivity (anti-dsDNA). Cohens kappa varied between 0.86-0.93. Time to seroconversion from PCR positivity was lowest for Abbott IgM and highest for Abbott IgG. NPV was highest for Abbott IgM <14 days post-PCR positivity and Abbott IgG [&ge;]14 days. ConclusionThe Abbott IgM assay exhibited the earliest response and greatest signal in most patients evaluated for serial sampling and had the highest NPV <14 days post-PCR positivity, suggesting its potential utility as an adjunct test to PCR early in disease course.

Next-Generation Sequencing based genomic surveillance has been widely implemented for identification and tracking of emerging SARS-CoV-2 variants to guide the Public Health response to the COVID-19 pandemic. Amplicon-based assays, such as the Illumina(R) COVIDSeq Test (RUO) and COVIDSeq Assay (RUO), enable scalable sequencing of SARS-CoV-2, leveraging V3 and V4 primer designs from the ARTIC community and DRAGEN COVID Lineage App analysis available on Illumina BaseSpace. We report here a comparison of COVIDSeq performance for SARS-CoV-2 genome reporting using the ARTIC V3 based primer pool (including primers for human control genes) that is provided with the COVIDSeq kit versus the ARTIC V4 based Illumina COVIDSeq V4 primer pool, using an optimized protocol and DRAGEN COVID Lineage App analysis. The data indicates that both primer pools enable robust reporting of SARS-CoV-2 variants. The Illumina COVIDSeq V4 primer pool has superior performance for SARS-CoV-2 genome reporting, particularly in samples with low virus load, and is therefore the recommended primer pool for genomic surveillance of SARS-CoV-2 for research use using COVIDSeq.

Recombination between SARS-CoV-2 virus variants can result in different viral properties (e.g., infectiousness or pathogenicity). In this report, we describe viruses with recombinant genomes containing signature mutations from Delta and Omicron variants. These genomes are the first evidence for a Delta-Omicron hybrid Spike protein in the United States.

BACKGROUND: Half of positive blood cultures in pediatric emergency departments (PEDs) represent contaminants, driving unnecessary hospitalization, antibiotic exposure, and repeat visits. A clinical decision rule derived at CHU Sainte-Justine showed 99% sensitivity and 60% specificity for distinguishing bacteremia from contaminants but had not been externally validated. We sought to validate this rule in an independent pediatric cohort. METHODS: This retrospective diagnostic study spanned from January 2015 to May 2025 at a tertiary PED in Switzerland, using positive blood cultures from patients younger than 16 years. The four predictors (Gram-negative organisms or Gram-positive cocci in pairs or chains; time to positivity <17 hours; indwelling device; suspected osteoarticular infection) classified each case as low, moderate, or high risk. The primary outcome was bacteremia, adjudicated by two independent reviewers, based on organism identity and infectious disease specialist's assessment. Diagnostic accuracy was assessed with 95% CIs. RESULTS: Of 130 children enrolled (median age 3.8 years [IQR 0.9-9.9]; 61.5% male), 78 (60.0%) had true bacteremia. The rule yielded a sensitivity of 97.4% (95% CI, 91.0-99.7), specificity of 69.2% (95% CI, 54.9-81.3), positive predictive value of 82.6% (95% CI, 73.3-89.7), and negative predictive value of 94.7% (95% CI, 82.3-99.4). Both false-negatives were immunocompetent children with methicillin-susceptible Staphylococcus aureus bacteremia without indwelling devices. Among contaminants, 71% received antibiotics under usual care versus 31% classified as moderate or high risk by the rule. CONCLUSIONS: This first external validation supports the Sainte-Justine rule in a distinct pediatric population, preserving sensitivity with higher specificity. Multicenter validation is warranted before adoption.

SARS-CoV-2 viremia has been demonstrated in some patients using molecular assays. Here we demonstrate detection of SARS-CoV-2 antigen in a cohort of hospitalized patients using a rapid diagnostic test from Anhui Deepblue Medical Technology Co., Ltd. We detected antigen in serum from 11 of 13 patients at time points ranging from three to eighteen days from symptom onset and observed that the disappearance of an antigen signal was associated with seroconversion. These results demonstrate proof of principle use of a rapid antigen test with serum samples in a format compatible with point of care testing.