High-throughput Sequencing to Identify Bacteremia in Children with Cancer.

Current methods to diagnose bacteremia are limited. In this pilot study of children with cancer presenting with fever, we determined the concordance between a novel high-throughput sequencing platform called BacCapSeq and blood culture. High-throughput sequencing had modest concordance with blood culture. Discordant organisms included those with both unlikely or potential clinical relevance.

Impact of Implementing the Cerebrospinal Fluid FilmArray Meningitis/Encephalitis Panel on Duration of Intravenous Acyclovir Treatment.

Background: Herpes simplex virus-1 is the most common cause of sporadic encephalitis worldwide and requires prompt antiviral treatment. Traditionally, herpes simplex virus-1 (HSV-1) cerebrospinal fluid (CSF) testing is conducted using standalone polymerase chain reaction (PCR). The BioFire CSF FilmArray Meningitis/Encephalitis Panel (BioFire ME Panel) was introduced in 2015 at our institution, providing an alternative method of HSV-1 CSF testing. This study assesses the impact of the BioFire ME Panel on duration of intravenous acyclovir treatment. Methods: A retrospective review of electronic medical records between 2010 and 2019 was performed. Information on intravenous acyclovir treatment and HSV-1 CSF testing was collected and analyzed. Our descriptive analysis included Mann-Whitney tests, 2 proportion Z-tests, and logistic regression. Results: Our CSF HSV-1-negative cohort included 524 BioFire patients (125 pediatric, 399 adult) and 287 standalone PCR patients (115 pediatric, 172 adult). Across both pediatric and adult groups, patients who were tested for HSV-1 with the BioFire ME Panel had shorter average (SD) durations of intravenous acyclovir treatment (pediatric: 2.00 [5.71] days; adult: 3.26 [6.59] days) compared with patients tested with standalone PCR (pediatric: 4.83 [8.62] days; adult: 4.93 [8.46] days; P < .001). Time from lumbar puncture collection to HSV-1 results was additionally faster on average for the BioFire ME Panel than the standalone PCR (P < .001). Conclusions: The implementation of the BioFire ME Panel shortened CSF HSV-1 PCR result time and intravenous acyclovir duration. The shortened treatment and testing times from the BioFire ME Panel implementation may reduce hospital treatment costs and unnecessary use of antiviral treatments.

Get2PrEP: An Electronic Medical Record Laboratory Comment Increased Safe Sex Counseling But Not Preexposure Prophylaxis Services at a Large Urban Academic Medical Center in Northern Manhattan.

BACKGROUND: HIV preexposure prophylaxis (PrEP) remains underutilized despite its efficacy and potential population impact. Achieving PrEP's full potential depends on providers who are knowledgeable and comfortable prescribing it to individuals at risk of acquiring HIV. Previous educational interventions targeting provider-related uptake barriers have had limited success. We designed and tested an electronic medical record (EMR) interpretative comment to improve the delivery of PrEP. METHODS: An EMR comment provided information on PrEP eligibility and referral resources to providers delivering positive chlamydia and gonorrhea results. Positive test results for bacterial sexually transmitted infections before intervention (January 1, 2019-August 23, 2019) and after intervention (August 24, 2019-December 31, 2019) were identified. A retrospective chart review was conducted to ascertain provider documentation of PrEP discussions or provision, HIV prevention discussions, and HIV screening. Pretest-posttest analysis was performed to compare the provision of PrEP and HIV prevention services. RESULTS: We reviewed 856 preintervention encounters spanning 8 months and 461 postencounters spanning 4 months. Patient demographics were comparable. We observed an increase in provider documentation of safe sex and condom counseling (odds ratios [ORs], 1.2 [95% confidence interval {CI}, 1.07-1.18] and 1.11 [95% CI, 1.05-1.17], respectively), and the absence of any HIV prevention discussion decreased (OR, 0.85; 95% CI, 0.80-0.90), but not HIV screening or PrEP documentation. CONCLUSIONS: We demonstrated that an EMR laboratory comment had a modest effect on increasing risk reduction counseling, although not HIV screening or PrEP prescriptions. Future strategies to encourage provider delivery of sexual health services may benefit from more targeted strategies that combine behavioral and information technology approaches.

Prevalence of Gastrointestinal Pathogens Detected by Multiplex Polymerase Chain Reaction in a Prospective Cohort of Men Who Have Sex With Men Taking Human Immunodeficiency Virus Preexposure Prophylaxis-New York City, 2019-2020.

Multiplex polymerase chain reaction testing for gastrointestinal pathogens was performed on a longitudinal cohort of 110 men who have sex with men taking human immunodeficiency virus preexposure prophylaxis. At least 1 pathogen was detected among 50 (45%) participants, with some participants testing positive for the same pathogen on multiple consecutive visits over a period of months.

The use of respiratory pathogen panel nasal polymerase chain reaction testing in predicting cutaneous enteroviral infections in the pediatric population.

BACKGROUND/OBJECTIVE: To characterize the relationship between the presence of enteroviral skin infection, defined as a positive skin polymerase chain reaction (PCR) test, and the nasopharyngeal (NP) respiratory pathogen panel (RPP) PCR test which includes enterovirus/rhinovirus as an analyte. METHODS: A retrospective chart review was performed on 543 subjects, age 18 years or younger, who had enterovirus (EV) skin swabs performed at an academic medical center in New York City between September 2014 and November 2019. Those patients with positive EV skin PCR were considered to have an enteroviral skin infection, and those with a negative EV skin PCR were considered not to have an enteroviral skin infection. Of those 543 children who had EV skin PCR, 170 also had an NP swab RPP performed. These NP swab RPP results were characterized as positive or negative, and if positive, it was noted if the patient was positive or negative for enterovirus/rhinovirus. The positive predictive value (PPV), negative predictive value (NPV), specificity, and sensitivity of a NP swab RPP for enteroviral skin infection were then calculated. RESULTS: An enterovirus/rhinovirus NP swab RPP had a NPV of 95%, PPV of 43%, sensitivity of 90%, and specificity of 62% for cutaneous enterovirus infection. CONCLUSION: The enteroviral skin PCR test is an assay that was validated at this institution. In clinically suspicious cases of EV, a positive NP swab RPP for enterovirus/rhinovirus is a sensitive test. A negative test is highly predictive of not having EV on the skin. Although further data are needed, given that NP swab RPP is readily available, these data may suggest that an NP swab RPP, when appropriately utilized, can support or exclude a clinical diagnosis of cutaneous enterovirus in the pediatric population.

Field-deployable, rapid diagnostic testing of saliva for SARS-CoV-2.

To safely re-open economies and prevent future outbreaks, rapid, frequent, point-of-need, SARS-CoV-2 diagnostic testing is necessary. However, existing field-deployable COVID-19 testing methods require the use of uncomfortable swabs and trained providers in PPE, while saliva-based methods must be transported to high complexity laboratories for testing. Here, we report the development and clinical validation of High-Performance Loop-mediated isothermal Amplification (HP-LAMP), a rapid, saliva-based, SARS-CoV-2 test with a limit of detection of 1.4 copies of virus per µl of saliva and a sensitivity and specificity with clinical samples of > 96%, on par with traditional RT-PCR based methods using swabs, but can deliver results using only a single fluid transfer step and simple heat block. Testing of 120 patient samples in 40 pools comprised of 5 patient samples each with either all negative or a single positive patient sample was 100% accurate. Thus, HP-LAMP may enable rapid and accurate results in the field using saliva, without need of a high-complexity laboratory.

Pretest Symptom Duration and Cycle Threshold Values for Severe Acute Respiratory Syndrome Coronavirus 2 Reverse-Transcription Polymerase Chain Reaction Predict Coronavirus Disease 2019 Mortality.

BACKGROUND: The relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load and patient symptom duration in both in- and outpatients, and the impact of these factors on patient outcomes, are currently unknown. Understanding these associations is important to clinicians caring for patients with coronavirus disease 2019 (COVID-19). METHODS: We conducted an observational study between March 10 and May 30, 2020 at a large quaternary academic medical center in New York City. Patient characteristics, laboratory values, and clinical outcomes were abstracted from the electronic medical records. Of all patients tested for SARS-CoV-2 during this time (N = 16 384), there were 5467 patients with positive tests, 4254 of which had available cycle threshold (Ct) values and were included in further analysis. Univariable and multivariable logistic regression models were used to test associations between Ct values, duration of symptoms before testing, patient characteristics, and mortality. The primary outcome is defined as death or discharge to hospice. RESULTS: Lower Ct values at diagnosis (ie, higher viral load) were associated with significantly higher mortality among both in- and outpatients. It is interesting to note that patients with a shorter time since the onset of symptoms to testing had a worse prognosis, with those presenting less than 3 days from symptom onset having 2-fold increased odds of death. After adjusting for time since symptom onset and other clinical covariates, Ct values remained a strong predictor of mortality. CONCLUSIONS: Severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction Ct value and duration of symptoms are strongly associated with mortality. These 2 factors add useful information for clinicians to risk stratify patients presenting with COVID-19.

Cycle Thresholds Among Solid Organ Transplant Recipients Testing Positive for SARS-CoV-2.

BACKGROUND: The optimal duration of transmission-based precautions among immunocompromised patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. METHODS: Retrospective review of patients with solid organ transplant with positive SARS-CoV-2 polymerase chain reaction result from nasopharyngeal specimens admitted to the hospital between March 13, 2020 and May 15, 2020. RESULTS: Twenty-one percent of solid organ transplant recipients with positive SARS-CoV-2 polymerase chain reaction detected ≥20 d after symptom onset (or after first positive test among asymptomatic individuals) had a low cycle threshold (ie, high viral load). The majority of these patients were asymptomatic or symptomatically improved. CONCLUSIONS: Solid organ transplant recipients may have prolonged high viral burden of SARS-CoV-2. Further data are needed to understand whether cycle threshold data can help inform strategies for prevention of healthcare-associated transmission of SARS-CoV-2 and for appropriate discontinuation of transmission-based precautions.

Direct diagnostic testing of SARS-CoV-2 without the need for prior RNA extraction.

The COVID-19 pandemic has resulted in an urgent need for a rapid, point of care diagnostic testing that could be rapidly scaled on a worldwide level. We developed and tested a highly sensitive and robust assay based on reverse transcription loop mediated isothermal amplification (RT-LAMP) that uses readily available reagents and a simple heat block using contrived spike-in and actual clinical samples. RT-LAMP testing on RNA-spiked samples showed a limit of detection (LoD) of 2.5 copies/µl of viral transport media. RT-LAMP testing directly on clinical nasopharyngeal swab samples in viral transport media had an 85% positive percentage agreement (PPA) (17/20), and 100% negative percentage agreement (NPV) and delivered results in 30 min. Our optimized RT-LAMP based testing method is a scalable system that is sufficiently sensitive and robust to test for SARS-CoV-2 directly on clinical nasopharyngeal swab samples in viral transport media in 30 min at the point of care without the need for specialized or proprietary equipment or reagents. This cost-effective and efficient one-step testing method can be readily available for COVID-19 testing world-wide, especially in resource poor settings.

At-Home Testing for Sexually Transmitted Infections During the COVID-19 Pandemic.

During the COVID-19 pandemic in New York City, NewYork-Presbyterian Hospital provided HIV prevention patients with gonorrhea/chlamydia testing kits at home. This report describes the program implementation to provide other sexual health clinics with a roadmap in adapting to a "new normal" in providing comprehensive sexual health care virtually to patients.

Outcomes of Neonates Born to Mothers With Severe Acute Respiratory Syndrome Coronavirus 2 Infection at a Large Medical Center in New York City.

Importance: Limited data on vertical and perinatal transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and health outcomes of neonates born to mothers with symptomatic or asymptomatic coronavirus disease 2019 (COVID-19) are available. Studies are needed to inform evidence-based infection prevention and control (IP&C) policies. Objective: To describe the outcomes of neonates born to mothers with perinatal SARS-CoV-2 infection and the IP&C practices associated with these outcomes. Design, Setting, and Participants: This retrospective cohort analysis reviewed the medical records for maternal and newborn data for all 101 neonates born to 100 mothers positive for or with suspected SARS-CoV-2 infection from March 13 to April 24, 2020. Testing for SARS-CoV-2 was performed using Cobas (Roche Diagnostics) or Xpert Xpress (Cepheid) assays. Newborns were admitted to well-baby nurseries (WBNs) (82 infants) and neonatal intensive care units (NICUs) (19 infants) in 2 affiliate hospitals at a large academic medical center in New York, New York. Newborns from the WBNs roomed-in with their mothers, who were required to wear masks. Direct breastfeeding after appropriate hygiene was encouraged. Exposures: Perinatal exposure to maternal asymptomatic/mild vs severe/critical COVID-19. Main Outcomes and Measures: The primary outcome was newborn SARS-CoV-2 testing results. Maternal COVID-19 status was classified as asymptomatic/mildly symptomatic vs severe/critical. Newborn characteristics and clinical courses were compared across maternal COVID-19 severity. Results: In total, 141 tests were obtained from 101 newborns (54 girls [53.5%]) on 0 to 25 days of life (DOL-0 to DOL-25) (median, DOL-1; interquartile range [IQR], DOL-1 to DOL-3). Two newborns had indeterminate test results, indicative of low viral load (2.0%; 95% CI, 0.2%-7.0%); 1 newborn never underwent retesting but remained well on follow-up, and the other had negative results on retesting. Maternal severe/critical COVID-19 was associated with newborns born approximately 1 week earlier (median gestational age, 37.9 [IQR, 37.1-38.4] vs 39.1 [IQR, 38.3-40.2] weeks; P = .02) and at increased risk of requiring phototherapy (3 of 10 [30.0%] vs 6 of 91 [7.0%]; P = .04) compared with newborns of mothers with asymptomatic/mild COVID-19. Fifty-five newborns were followed up in a new COVID-19 Newborn Follow-up Clinic at DOL-3 to DOL-10 and remained well. Twenty of these newborns plus 3 newborns followed up elsewhere had 32 nonroutine encounters documented at DOL-3 to DOL-25, and none had evidence of SARS-CoV-2 infection, including 6 with negative retesting results. Conclusions and Relevance: No clinical evidence of vertical transmission was identified in 101 newborns of mothers positive for or with suspected SARS-CoV-2 infection, despite most newborns rooming-in and direct breastfeeding practices.

Carbapenemase-producing Enterobacterales causing secondary infections during the COVID-19 crisis at a New York City hospital.

BACKGROUND: Patients with COVID-19 may be at increased risk for secondary bacterial infections with MDR pathogens, including carbapenemase-producing Enterobacterales (CPE). OBJECTIVES: We sought to rapidly investigate the clinical characteristics, population structure and mechanisms of resistance of CPE causing secondary infections in patients with COVID-19. METHODS: We retrospectively identified CPE clinical isolates collected from patients testing positive for SARS-CoV-2 between March and April 2020 at our medical centre in New York City. Available isolates underwent nanopore sequencing for rapid genotyping, antibiotic resistance gene detection and phylogenetic analysis. RESULTS: We identified 31 CPE isolates from 13 patients, including 27 Klebsiella pneumoniae and 4 Enterobacter cloacae complex isolates. Most patients (11/13) had a positive respiratory culture and 7/13 developed bacteraemia; treatment failure was common. Twenty isolates were available for WGS. Most K. pneumoniae (16/17) belonged to ST258 and encoded KPC (15 KPC-2; 1 KPC-3); one ST70 isolate encoded KPC-2. E. cloacae isolates belonged to ST270 and encoded NDM-1. Nanopore sequencing enabled identification of at least four distinct ST258 lineages in COVID-19 patients, which were validated by Illumina sequencing data. CONCLUSIONS: While CPE prevalence has declined substantially in New York City in recent years, increased detection in patients with COVID-19 may signal a re-emergence of these highly resistant pathogens in the wake of the global pandemic. Increased surveillance and antimicrobial stewardship efforts, as well as identification of optimal treatment approaches for CPE, will be needed to mitigate their future impact.

A double-edged sword: Prolonged detection of SARS-COV-2 in patients receiving cancer directed therapy.

INTRODUCTION: SARS-CoV-2 (S-2) infection duration and its impact on patients with cancer and mild to moderate COVID-19 undergoing cancer-directed therapy (CDT), especially in the underserved population, is not well described. We conducted a retrospective study to analyze S-2 positive (+) patients on CDT to describe the S-2 duration and its impact on CDT. METHODS: Two hundred ninety-nine patients with cancer were tested with nasopharyngeal (NP) S-2 PCR assay at Columbia University Medical Irving Center (CUIMC), a Minority-NCI Community Oncology site, of which 77 (26%) tested positive. We retrospectively analyzed 26 S-2 (+) patients with mild-to-moderate COVID-19 receiving CDT who consented to the study. NP PCR was repeated every 1 to 2 weeks until 2 successive negative (-) PCRs were obtained prior to restarting CDT. Time to 2 (-) PCR and serology results were recorded. Cycling thresholds (Ct) were obtained for S-2 specific targets and represented an indirect measure of viral load. RESULTS: Demographics of N = 26 patients are: Hispanic (N = 17, 65%), Black (N = 1, 4%), White (N = 7, 27%), and undeclared (N = 1, 4%). Among the tumor histologies represented, gastrointestinal (N = 9, 35%), breast (N = 5, 19%), and sarcoma (N = 3, 12%) were most common. Median time to 2 (-) PCR was 32 days. Twenty patients required greater than 14 days to achieve 2 sequential (-) swabs. CDT was delayed in 21 patients (81%) of whom three experienced disease progression, likely attributed to an interruption in CDT, which was delayed by a mean of 53 days. Interestingly, nine (41%) patients had Ct values greater than 34 for the pan SARS target and seven (32%) patients had Ct values greater than 34 for the SARS-COV-2 target. Sixteen of 16 patients on CDT, tested positive for IgG antibodies at the time of consent, despite protracted viral detectability by NP PCR. CONCLUSION: Patients receiving CDT appear to have prolonged detectable S-2 by PCR, which can lead to interruption of CDT and POD in patients. We believe and recommend that patients with asymptomatic to mild COVID-19 and aggressive malignancies are at greatest risk for cancer related morbidity and mortality due to CDT cessation and should be considered for continued CDT without interruption. Ct values and serology testing are tools that can help identify those patients on CDT who may be at greatest risk of worsening COVID-19 or of spreading S-2.

Burden and risk factors for inappropriate Clostridioides Difficile infection testing among hospitalized patients.

BACKGROUND: The purpose of this study was to identify the burden and risk factors for inappropriate Clostridioides difficile infection (CDI) testing. METHODS: This was a retrospective cohort study among adults hospitalized between 2010 and 2019. Inappropriate CDI testing was defined as a formed stool specimen, an order within 7 days of a previously negative test, or an order within 24 hours of laxative administration. RESULTS: A total of 51,302 CDI orders were placed for 29,840 unique patients. 59% were appropriate and 41% were inappropriate. An additional 24% of the appropriate orders never resulted. Risk factors for inappropriate testing included orders placed by a nurse practitioner, orders placed by high-ordering providers, specific hospital units, fever, and leukocytosis. CONCLUSIONS: Nearly half of all CDI orders were inappropriate among hospitalized patients, and an additional 24% of test results never returned. Provider- and patient-level risk factors included type of provider, specific hospital units, and signs of sepsis.

Characterization of wound microbes in epidermolysis bullosa: Results from the epidermolysis bullosa clinical characterization and outcomes database.

BACKGROUND/OBJECTIVES: Patients with epidermolysis bullosa (EB) require care of wounds that are colonized or infected with bacteria. A subset of EB patients are at risk for squamous cell carcinoma, and bacterial-host interactions have been considered in this risk. The EB Clinical Characterization and Outcomes Database serves as a repository of information from EB patients at multiple centers in the United States and Canada. Access to this resource enabled broad-scale analysis of wound cultures. METHODS: A retrospective analysis of 739 wound cultures from 158 patients from 13 centers between 2001 and 2018. RESULTS: Of 152 patients with a positive culture, Staphylococcus aureus (SA) was recovered from 131 patients (86%), Pseudomonas aeruginosa (PA) from 56 (37%), and Streptococcus pyogenes (GAS) from 34 (22%). Sixty-eight percent of patients had cultures positive for methicillin-sensitive SA, and 47%, methicillin-resistant SA (18 patients had cultures that grew both methicillin-susceptible and methicillin-resistant SA at different points in time). Of 15 patients with SA-positive cultures with recorded mupirocin susceptibility testing, 11 had mupirocin-susceptible SA and 6 patients mupirocin-resistant SA (2 patients grew both mupirocin-susceptible and mupirocin-resistant SA). SCC was reported in 23 patients in the entire database, of whom 10 had documented wound cultures positive for SA, PA, and Proteus species in 90%, 50%, and 20% of cases, respectively. CONCLUSIONS: SA and PA were the most commonly isolated bacteria from wounds. Methicillin resistance and mupirocin resistance were reported in 47% and 40% of patients tested, respectively, highlighting the importance of ongoing antimicrobial strategies to limit antibiotic resistance.

SARS-CoV-2 Viral Load Predicts Mortality in Patients with and without Cancer Who Are Hospitalized with COVID-19.

Patients with cancer may be at increased risk of severe coronavirus disease 2019 (COVID-19), but the role of viral load on this risk is unknown. We measured SARS-CoV-2 viral load using cycle threshold (CT) values from reverse-transcription polymerase chain reaction assays applied to nasopharyngeal swab specimens in 100 patients with cancer and 2,914 without cancer who were admitted to three New York City hospitals. Overall, the in-hospital mortality rate was 38.8% among patients with a high viral load, 24.1% among patients with a medium viral load, and 15.3% among patients with a low viral load (p < 0.001). Similar findings were observed in patients with cancer (high, 45.2% mortality; medium, 28.0%; low, 12.1%; p = 0.008). Patients with hematologic malignancies had higher median viral loads (CT = 25.0) than patients without cancer (CT = 29.2; p = 0.0039). SARS-CoV-2 viral load results may offer vital prognostic information for patients with and without cancer who are hospitalized with COVID-19.

A review of newborn outcomes during the COVID-19 pandemic.

As the COVID-19 pandemic continues to spread worldwide, it is crucial that we determine populations that are at-risk and develop appropriate clinical care policies to protect them. While several respiratory illnesses are known to seriously impact pregnant women and newborns, preliminary data on the novel SARS-CoV-2 Coronavirus suggest that these groups are no more at-risk than the general population. Here, we review the available literature on newborns born to infected mothers and show that newborns of mothers with positive/suspected SARS-CoV-2 infection rarely acquire the disease or show adverse clinical outcomes. With this evidence in mind, it appears that strict postnatal care policies, including separating mothers and newborns, discouraging breastfeeding, and performing early bathing, may be more likely to adversely impact newborns than they are to reduce the low risk of maternal transmission of SARS-CoV-2 or the even lower risk of severe COVID-19 disease in otherwise healthy newborns.

Direct diagnostic testing of SARS-CoV-2 without the need for prior RNA extraction.

The COVID-19 pandemic has resulted in an urgent global need for rapid, point-of-care diagnostic testing. Existing methods for nucleic acid amplification testing (NAAT) require an RNA extraction step prior to amplification of the viral RNA. This step necessitates the use of a centralized laboratory or complex and costly proprietary cartridges and equipment, and thereby prevents low-cost, scalable, point-of-care testing. We report the development of a highly sensitive and robust, easy-to-implement, SARS-CoV-2 test that utilizes isothermal amplification and can be run directly on viral transport media following a nasopharyngeal swab without the need for prior RNA extraction. Our assay provides visual results in 30 min with 85% sensitivity, 100% specificity, and a limit of detection (LoD) of 2.5 copies/µl, and can be run using a simple heat block.

Clinical Performance of SARS-CoV-2 Molecular Tests.

Molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the gold standard for diagnosis of coronavirus disease 2019 (COVID-19), but the clinical performance of these tests is still poorly understood, particularly with regard to disease course, patient-specific factors, and viral shedding. From 10 March to 1 May 2020, NewYork-Presbyterian laboratories performed 27,377 SARS-CoV-2 molecular assays from 22,338 patients. Repeat testing was performed for 3,432 patients, of which 2,413 had initial negative and 802 had initial positive results. Repeat-tested patients were more likely to have severe disease and low viral loads. The negative predictive value of the first-day result among repeat-tested patients was 81.3% The clinical sensitivity of SARS-CoV-2 molecular assays was estimated between 58% and 96%, depending on the unknown number of false-negative results in single-tested patients. Conversion to negative was unlikely to occur before 15 to 20 days after initial testing or 20 to 30 days after the onset of symptoms, with 50% conversion occurring at 28 days after initial testing. Conversion from first-day negative to positive results increased linearly with each day of testing, reaching 25% probability in 20 days. Sixty patients fluctuated between positive and negative results over several weeks, suggesting that caution is needed when single-test results are acted upon. In summary, our study provides estimates of the clinical performance of SARS-CoV-2 molecular assays and suggests time frames for appropriate repeat testing, namely, 15 to 20 days after a positive test and the same day or next 2 days after a negative test for patients with high suspicion for COVID-19.