Regional and temporal variations affect the accuracy of variant-specific SARS-CoV-2 PCR assays

Monitoring the prevalence of SARS-CoV-2 variants is necessary to make informed public health decisions during the COVID-19 pandemic. PCR assays have received global attention, facilitating rapid understanding of variant dynamics because they are more accessible and scalable than genome sequencing. However, as PCR assays target only a few mutations, their accuracy could be compromised when these mutations are not exclusive to target variants. Here we show how to design variant-specific PCR assays with high sensitivity and specificity across different geographical regions by incorporating sequences deposited in the GISAID database. Furthermore, we demonstrate that several previously developed PCR assays have decreased accuracy outside their study areas. We introduce PRIMES, an algorithm that enables the design of reliable PCR assays, as demonstrated in our experiments to track dominant SARS-CoV-2 variants in local sewage samples. Our findings will contribute to improving PCR assays for SARS-CoV-2 variant surveillance. ImportanceMonitoring the introduction and prevalence of variants of concern (VOCs) and variants of interest (VOIs) in a community can help the local authorities make informed public health decisions. PCR assays can be designed to keep track of SARS-CoV-2 variants by measuring unique mutation markers that are exclusive to the target variants. However, the mutation markers can not be exclusive to the target variants depending on regional and temporal differences in variant dynamics. We introduce PRIMES, an algorithm that enables the design of reliable PCR assays for variant detection. Because PCR is more accessible, scalable, and robust to sewage samples over sequencing technology, our findings will contribute to improving global SARS-CoV-2 variant surveillance.

Longitudinal analysis of SARS-CoV-2 vaccine breakthrough infections reveal limited infectious virus shedding and restricted tissue distribution

The global effort to vaccinate people against SARS-CoV-2 in the midst of an ongoing pandemic has raised questions about the nature of vaccine breakthrough infections and the potential for vaccinated individuals to transmit the virus. These questions have become even more urgent as new variants of concern with enhanced transmissibility, such as Delta, continue to emerge. To shed light on how vaccine breakthrough infections compare with infections in immunologically naive individuals, we examined viral dynamics and infectious virus shedding through daily longitudinal sampling in a small cohort of adults infected with SARS-CoV-2 at varying stages of vaccination. The durations of both infectious virus shedding and symptoms were significantly reduced in vaccinated individuals compared with unvaccinated individuals. We also observed that breakthrough infections are associated with strong tissue compartmentalization and are only detectable in saliva in some cases. These data indicate that vaccination shortens the duration of time of high transmission potential, minimizes symptom duration, and may restrict tissue dissemination.

Mitigation of SARS-CoV-2 Transmission at a Large Public University

In the Fall of 2020, many universities saw extensive transmission of SARS-CoV-2 among their populations, threatening the health of students, faculty and staff, the viability of in-person instruction, and the health of surrounding communities.1, 2 Here we report that a multimodal "SHIELD: Target, Test, and Tell" program mitigated the spread of SARS-CoV-2 at a large public university, prevented community transmission, and allowed continuation of in-person classes amidst the pandemic. The program combines epidemiological modelling and surveillance (Target); fast and frequent testing using a novel and FDA Emergency Use Authorized low-cost and scalable saliva-based RT-qPCR assay for SARS-CoV-2 that bypasses RNA extraction, called covidSHIELD (Test); and digital tools that communicate test results, notify of potential exposures, and promote compliance with public health mandates (Tell). These elements were combined with masks, social distancing, and robust education efforts. In Fall 2020, we performed more than 1,000,000 covidSHIELD tests while keeping classrooms, laboratories, and many other university activities open. Generally, our case positivity rates remained less than 0.5%, we prevented transmission from our students to our faculty and staff, and data indicate that we had no spread in our classrooms or research laboratories. During this fall semester, we had zero COVID-19-related hospitalizations or deaths amongst our university community. We also prevented transmission from our university community to the surrounding Champaign County community. Our experience demonstrates that multimodal transmission mitigation programs can enable university communities to achieve such outcomes until widespread vaccination against COVID-19 is achieved, and provides a roadmap for how future pandemics can be addressed.

Daily sampling of early SARS-CoV-2 infection reveals substantial heterogeneity in infectiousness

The dynamics of SARS-CoV-2 replication and shedding in humans remain poorly understood. We captured the dynamics of infectious virus and viral RNA shedding during acute infection through daily longitudinal sampling of 60 individuals for up to 14 days. By fitting mechanistic models, we directly estimate viral reproduction and clearance rates, and overall infectiousness for each individual. Significant person-to-person variation in infectious virus shedding suggests that individual-level heterogeneity in viral dynamics contributes to superspreading. Viral genome load often peaked days earlier in saliva than in nasal swabs, indicating strong compartmentalization and suggesting that saliva may serve as a superior sampling site for early detection of infection. Viral loads and clearance kinetics of B.1.1.7 and non-B.1.1.7 viruses in nasal swabs were indistinguishable, however B.1.1.7 exhibited a significantly slower pre-peak growth rate in saliva. These results provide a high-resolution portrait of SARS-CoV-2 infection dynamics and implicate individual-level heterogeneity in infectiousness in superspreading.

Longitudinal assessment of diagnostic test performance over the course of acute SARS-CoV-2 infection

What is already known about this topic?Diagnostic tests and sample types for SARS-CoV-2 vary in sensitivity across the infection period. What is added by this report?We show that both RTqPCR (from nasal swab and saliva) and the Quidel SARS Sofia FIA rapid antigen tests peak in sensitivity during the period in which live virus can be detected in nasal swabs, but that the sensitivity of RTqPCR tests rises more rapidly in the pre-infectious period. We also use empirical data to estimate the sensitivities of RTqPCR and antigen tests as a function of testing frequency. What are the implications for public health practice?RTqPCR tests will be more effective than rapid antigen tests at identifying infected individuals prior to or early during the infectious period and thus for minimizing forward transmission (provided results reporting is timely). All modalities, including rapid antigen tests, showed >94% sensitivity to detect infection if used at least twice per week. Regular surveillance/screening using rapid antigen tests 2-3 times per week can be an effective strategy to achieve high sensitivity (>95%) for identifying infected individuals.

SARS-CoV-2 Infection And Longitudinal Fecal Screening In Malayan Tigers (Panthera tigris jacksoni), Amur Tigers (Panthera tigris altaica), And African Lions (Panthera leo krugeri) At The Bronx Zoo, New York, USA

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) emerged as the cause of a global pandemic in 2019-2020. In March 2020 New York City became the USA epicenter for the pandemic. On March 27, 2020 a Malayan tiger (Panthera tigris jacksoni) at the Bronx Zoo in New York City developed a cough and wheezing with subsequent inappetence. Over the next week, an additional Malayan tiger and two Amur tigers (P. t. altaica) in the same building and three lions (Panthera leo krugeri) in a separate building also became ill. The index case was immobilized, and physical examination and bloodwork results were unremarkable. Thoracic radiography and ultrasonography revealed peribronchial cuffing with bronchiectasis, and mild lung consolidation with alveolar-interstitial syndrome, respectively. SARS-CoV-2 RNA was identified by real-time, reverse transcriptase PCR (rRT-PCR) on oropharyngeal and nasal swabs and tracheal wash fluid. Cytologic examination of tracheal wash fluid revealed necrosis, and viral RNA was detected in necrotic cells by in situ hybridization, confirming virus-associated tissue damage. SARS-CoV-2 was isolated from the tracheal wash fluid of the index case, as well as the feces from one Amur tiger and one lion. Fecal viral RNA shedding was confirmed in all seven clinical cases and an asymptomatic Amur tiger. Respiratory signs abated within 1-5 days for most animals, though persisted intermittently for 16 days in the index case. Fecal RNA shedding persisted for as long as 35 days beyond cessation of respiratory signs. This case series describes the clinical presentation, diagnostic evaluation, and management of tigers and lions infected with SARS-CoV-2, and describes the duration of viral RNA fecal shedding in these cases. This report documents the first known natural transmission of SARS-CoV-2 from humans to animals in the USA, and is the first report of SARS-CoV-2 in non-domestic felids.

From people to Panthera: Natural SARS-CoV-2 infection in tigers and lions at the Bronx Zoo

We describe the first cases of natural SARS-CoV-2 infection detected in animals in the United States. In March 2020, four tigers and three lions at the Bronx Zoo developed mild respiratory signs. SARS-CoV-2 RNA was detected by rRT-PCR in respiratory secretions and/or feces from all seven affected animals; viral RNA and/or antibodies were detected in their keepers. SARS-CoV-2 was isolated from respiratory secretions or feces from three affected animals; in situ hybridization co-localized viral RNA with cellular damage. Whole genome sequence and haplotype network analyses showed tigers and lions were infected with two different SARS-CoV-2 strains, suggesting independent viral introductions. The source of SARS-CoV-2 infection in the lions is unknown. Epidemiological data and genetic similarities between keeper and tiger viruses indicate human to animal transmission.

Saliva-Based Molecular Testing for SARS-CoV-2 that Bypasses RNA Extraction

Convenient, repeatable, large-scale molecular testing for SARS-CoV-2 would be a key weapon to help control the COVID-19 pandemic. Unfortunately, standard SARS-CoV-2 testing protocols are invasive and rely on numerous items that can be subject to supply chain bottlenecks, and as such are not suitable for frequent repeat testing. Specifically, personal protective equipment (PPE), nasopharyngeal (NP) swabs, the associated viral transport media (VTM), and kits for RNA isolation and purification have all been in short supply at various times during the COVID-19 pandemic. Moreover, SARS-CoV-2 is spread through droplets and aerosols transmitted through person-to-person contact, and thus saliva may be a relevant medium for diagnosing SARS-CoV-2 infection status. Here we describe a saliva-based testing method that bypasses the need for RNA isolation/purification. In experiments with inactivated SARS-CoV-2 virus spiked into saliva, this method has a limit of detection of 500-1000 viral particles per mL, rivalling the standard NP swab method, and initial studies also show excellent performance with 100 clinical samples. This saliva-based process is operationally simple, utilizes readily available materials, and can be easily implemented by existing testing sites, thus allowing for high-throughput, rapid, and repeat testing of large populations. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

Effect of stroke volume variability-guided intraoperative fluid restriction on liver and renal function in patients undergoing hepatic lobectomy / 中华麻醉学杂志

Objective To investigate the effect of stroke volume variability (SVV)-guided intraoperative fluid restriction on liver and renal function in patients undergoing hepatic lobectomy. Methods Forty ASA Ⅰ - Ⅲpatients of both sexes aged 33-60 yr weighing 52-80 kg undergoing elective hepatic lobectomy were randomly divided into 2 groups ( n = 20 each): group A routine fluid administration and group B restricted fluid administration.Anesthesia was induced with iv lidocaine, fentanyl and TCI of propofol (target plasma concentration 3-4 μg/ml).Tracheal intubation was facilitated with cisatracurium 0.2 mg/kg. The patients were mechanically ventilated.PETCO2 was maintained at 32-38 mm Hg. Anesthesia was maintained with 1%-2% sevoflurane inhalation and intermittent iv boluses of fentanyl and cisatracurium. BIS value was maintained at 40-60. Radial artery was cannulated and connected to continuous cardiac output monitor (Edwards Lifeaciences, USA). ECG, MAP, CVP and SVVtained at 5-7 in group A and 11-13 in group B. Blood loss, urine output and the amount of RBC and plasma infused during operation were recorded. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (TP), albumin (ALB), total bilirubin ( TBIL), direct bilirubin ( DBIL), blood urea nitrogen (BUN), creatinine (Cr) and lactate and Hb, Hct were measured the day before surgery (baseline) and at day 1,3 and 5 after operation. Results The hemodynamic parameters were maintained within normal limits during operation in both groups. The blood loss, the amount of RBC and plasma infused and urine output during operation were significantly less, while the serum TP and ALB concentrations were higher on the 1st postoperative day in group B than in group A. The serum levels of ALT, AST, TBIL and DBIL were significantly increased and serum concentrations of TP and ALB and Hb,Hct decreased, but there was no significant change in serum BUN and Cr concentrations and lactate after operation as compared with the baseline values before operation in both groups. There were no significant differences in serum levels of ALT, AST, TBIL, DBIL, BUN, Cr, lactate,Hb and Hct after operation between the 2 groups. Conclusion SVV can guide effectively intraoperative fluid restriction in patients undergoing hepatic lobectomy.

The Effect of Psychologic Nursing on Post - stroke Depression / 中国组织工程研究

Objective To investigate the effect of psychologic nursing on the rehabilitation for post-stroke depression(PSD) patients. Method 62 patients of 98 PSD patients were divided into 31couples. According to age, sex, course of illness and statge of illness, the patients were divided into rehabilitation nursing ( interference group) and routine nursing ( control group) with CES - D ( Center of epidemi ological survey - depression Scale ) and CNFD ( Criterion of nervous function defect). Every couple was compared with each other. Result The score of two groups before treatment was not obviously different(p＞ 0. 05). Two scores in two groups after treatment were obviously better than those of before treatment. Two scores of interference group were significantly higher compared with control group ( p ＜ 0. 05). Conclusion Interference of psychologic nursing is effective in treating post - stroke depression.