CT findings and dynamic changes of COVID-19 in the patients younger than 18 years old infected with SARS-CoV-2 omicron variant

Objective: To investigate the chest computed tomography (CT) manifestations and dynamic changes of coronavirus disease 2019 (COVID-19) in the patients younger than 18 years old infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant, and to provide a basis for determining the chest CT changes and efficacy of COVID-19 caused by Omicron virus variant in patients younger than 18 years old. Methods The clinical and imaging data of 30 cases of patients younger than 18 years old infected with COVID-19 Omicron variant, who admitted to the Third People's Hospital of Shenzhen from February 11 to March 26, 2022 were collected and retrospectively analyzed. The clinical manifestations, imaging features and dynamic changes of lesions were summarized. Results A total of 41 intrapulmonary lesions in 30 patients with COVID-19 caused by SARS-CoV-2 Omicron variant. The main manifestations were patchy or nodular ground-glass opacities and/or consolidation, with focal subpleural distribution, lesions mainly occur in the right lung (70.73%, 29/41). There were 42 lesion morphologies, with 22 (52.38%) striped shadows and 16 (38.10%) nodular shadows, with small lamellar and patchy shadows predominating. There were 36 lesion density variations, with ground glass shadows being the most common, with a total of 24 ground glass shadows (66.66%) in each lobe of the lung, and also 6 consolidation lesions (16.67%) and 6 mixed ground glass opacity and consolidation lesions (16.67%). With the progression of the disease, lesions gradually enlarged, appeared on the 2nd day (312.93 mm3), peaked on the 9th day (1 837.18 mm3). The average absorption time of the lesions was (16+or-3) days, and there was no significant difference between the absorption time of patchy and nodular lesions (ground glass and/or consolidation) (t=0.853, P > 0.05). The lesions showed focal ground-glass opacity in the early stage, 77.78% lesions were absorbed after treatment in the late stage. Inflammatory nodules were absorbed slowly (9-19 days), without residual fibrotic changes. Conclusions The imaging manifestations of COVID-19 in patients younger than 18 years old infected with SARS-CoV-2 Omicron variant have certain characteristics, showed patchy or nodular ground glass opacities and/or consolidation, mainly distributed in the subpleural area, with small and few lesions and slow change, didn't remain fibrosis. Being familiar with its clinical and imaging manifestations can assist in early diagnosis, but confirming the diagnosis requires a combination of epidemiological history, clinical symptoms, SARS-CoV-2 nucleic acid and radiological manifestations.

Macro-analysis of climatic factors for COVID-19 pandemic based on Köppen-Geiger climate classification.

This study integrated dynamic models and statistical methods to design a novel macroanalysis approach to judge the climate impacts. First, the incidence difference across Köppen-Geiger climate regions was used to determine the four risk areas. Then, the effective influence of climate factors was proved according to the non-climate factors' non-difference among the risk areas, multi-source non-major component data assisting the proof. It is found that cold steppe arid climates and wet temperate climates are more likely to transmit SARS-CoV-2 among human beings. Although the results verified that the global optimum temperature was around 10 °C, and the average humidity was 71%, there was evident heterogeneity among different climate risk areas. The first-grade and fourth-grade risk regions in the Northern Hemisphere and fourth-grade risk regions in the Southern Hemisphere are more sensitive to temperature. However, the third-grade risk region in the Southern Hemisphere is more sensitive to relative humidity. The Southern Hemisphere's third-grade and fourth-grade risk regions are more sensitive to precipitation.

Effect of vitamin D status on adult COVID-19 pneumonia induced by Delta variant: A longitudinal, real-world cohort study.

Objective: The effect of vitamin D status on adult COVID-19 pneumonia induced by Delta variant remains to be further explored. Methods: A longitudinal, real-world cohort study was performed. Artificial intelligence (AI) was used to identify and measure pneumonia lesions. All cases with pneumonia were divided into the vitamin D deficiency (VDD) and control groups according to serum 25-hydroxyvitamin D concentration. Lesion dynamics were observed within six time periods after the onset of pneumonia. Results: A total of 161 cases were included, of which 101 (63%) were male and 46 (29%) presented with pneumonia. The median age and baseline 25-hydroxyvitamin D concentrations were 37 years and 21 ng/ml, respectively. Age, fibrinogen, and SARS-CoV-2 IgG titer on admission were independent predictors for the onset of pneumonia. After the onset of pneumonia, patients in the VDD group (n = 18) had higher percentage of fever (33 vs. 7.1%; p = 0.04) than those in the control group (n = 28); the interval of pneumonia resolution was longer (28 vs. 21 days; p = 0.02); lesions progressed more rapidly (p = 0.01) within 3 to 7 days and improved more slowly (p = 0.007) within more than 28 days; notably, simultaneous interleukin-6 (18.7 vs. 14.6 pg/ml; p = 0.04) levels were higher, and cycle thresholds for N gene (22.8 vs. 31.3; p = 0.04) and ORF1ab gene (20.9 vs. 28.7; p = 0.03) were lower within 3 to 7 days. Conclusion: Vitamin D status may have effects on the progression and resolution, but not the onset of Delta variant-induced pneumonia in adults. Computed tomography image diagnosis system based on AI may have promising applications in the surveillance and diagnosis of novel SARS-CoV-2 variant-induced pneumonia.

Social media and parental trust for teachers: A qualitative study in China

Based on WeChat, the most popular social media application in contemporary China, this ethnographical case study reveals that the development of parental trust for teachers presents as an incremental process. It derives from parents' access to information shared by teachers online, unfolds across their engaging in constant collaborations with teachers, and increases with the formation of their close affective ties with teachers. Such a process is greatly dependent upon the formation of parents' liangxin (which is typically translated in English as "conscience") in regard to teachers. This study, conducted before the COVID-19 pandemic began, indicates that social media like WeChat has turned out to be a critical agent in parents' relationship with teachers that intervenes in their meaning-making process as well as their experience of building trust towards teachers. (PsycInfo Database Record (c) 2023 APA, all rights reserved)

Effect of female coronavirus disease 2019 vaccination on assisted reproductive outcomes: a systematic review and meta-analysis.

IMPORTANCE: The effect of coronavirus disease 2019 (COVID-19) vaccination on fertility warrants clarification in women undergoing assisted reproductive treatment. OBJECTIVE: To study the association between female COVID-19 vaccination and outcomes of assisted reproductive treatment. DATA SOURCES: PubMed, Embase, the Web of Science, Cochrane Library, and medRxiv and bioRxiv were searched for eligible studies from December 1, 2019, to November 30, 2022, with no language restrictions. STUDY SELECTION AND SYNTHESIS: Observational studies comparing assisted reproductive outcomes between women with and without COVID-19 vaccination were included. The pooled estimates were calculated using the random-effects models as mean differences (MDs), standardized MDs, or odds ratios with 95% confidence intervals (CIs). Heterogeneity was evaluated using the I2 statistic. MAIN OUTCOMES: The number of oocytes retrieved and clinical pregnancy rate. RESULTS: Twenty-one cohort studies involving a total of 19,687 treatment cycles were included. In a comparison of the vaccinated vs. unvaccinated groups, the pooled MD for oocyte number was -0.06 (95% CI, -0.51 to 0.39; I2 = 0), and the pooled odds ratio for clinical pregnancy was 0.95 (95% CI, 0.85-1.05; I2 = 0). Similarly, there were no statistically significant adverse effects identified in other outcomes determined a priori, including 4 cycle characteristics, 6 laboratory parameters, and 3 pregnancy indicators. Most results were consistently unchanged in subgroup and sensitivity analyses, with no evidence of publication bias according to Egger's test. CONCLUSION AND RELEVANCE: Our work did not find significant differences in assisted reproductive outcomes between vaccinated and unvaccinated women. However, more data are warranted to confirm the safety of COVID-19 vaccination for assisted reproductive treatment and in female fertility in general.

A smartphone-based online platform for clinical skills training and assessment with standardized patients: platform development and pilot study outcomes.

There are limitations and difficulties in the management of traditional in-person standardized patient (SP) practice. The latest developments in online communication tools and the COVID-19 pandemic have promoted the needs for online clinical skills training objectively. However, existing commercial online platforms may not meet the requests for SP-based medical simulation. This paper described the methodology applied to develop a smartphone-based online platform for the management of clinical skills training and assessment with remote SPs, and aimed to determine whether this new platform is acceptable or useful through a pilot run in September 2020. The post-run survey including questionnaire inspired by technological acceptance model and determinants of the perceived ease of use was used to assess the acceptability and usefulness of the platform. Twenty four-year students of clinical medicine participated in the pilot study with twenty SPs and ten faculties. Data from the post-run survey showed that there was a general recognition that the platform is easy to use among all the users. Two questions regarding the usefulness of the platform showed significant differences between the SPs/faculties and the students. More SPs found the platform useful as a training method than the students did. The faculties showed more attempts than the students to use this platform for clinical skills training in the future. This smartphone-based online platform was widely accepted among the tested students, SPs and faculties, which meets the requests and challenges of the new era. It provides an effective approach for clinical skills training and assessment with remote SPs.

Medical implementation practice and its medical performance evaluation of a giant makeshift hospital during the COVID-19 pandemic: An innovative model response to a public health emergency in Shanghai, China.

Introduction: In confronting the sudden COVID-19 epidemic, China and other countries have been under great pressure to block virus transmission and reduce fatalities. Converting large-scale public venues into makeshift hospitals is a popular response. This addresses the outbreak and can maintain smooth operation of a country or region's healthcare system during a pandemic. However, large makeshift hospitals, such as the Shanghai New International Expo Center (SNIEC) makeshift hospital, which was one of the largest makeshift hospitals in the world, face two major problems: Effective and precise transfer of patients and heterogeneity of the medical care teams. Methods: To solve these problems, this study presents the medical practices of the SNIEC makeshift hospital in Shanghai, China. The experiences include constructing two groups, developing a medical management protocol, implementing a multi-dimensional management mode to screen patients, transferring them effectively, and achieving homogeneous quality of medical care. To evaluate the medical practice performance of the SNIEC makeshift hospital, 41,941 infected patients were retrospectively reviewed from March 31 to May 23, 2022. Multivariate logistic regression method and a tree-augmented naive (TAN) Bayesian network mode were used. Results: We identified that the three most important variables were chronic disease, age, and type of cabin, with importance values of 0.63, 0.15, and 0.11, respectively. The constructed TAN Bayesian network model had good predictive values; the overall correct rates of the model-training dataset partition and test dataset partition were 99.19 and 99.05%, respectively, and the respective values for the area under the receiver operating characteristic curve were 0.939 and 0.957. Conclusion: The medical practice in the SNIEC makeshift hospital was implemented well, had good medical care performance, and could be copied worldwide as a practical intervention to fight the epidemic in China and other developing countries.

Medical implementation practice and its medical performance evaluation of a giant makeshift hospital during the COVID-19 pandemic: An innovative model response to a public health emergency in Shanghai, China

Introduction In confronting the sudden COVID-19 epidemic, China and other countries have been under great pressure to block virus transmission and reduce fatalities. Converting large-scale public venues into makeshift hospitals is a popular response. This addresses the outbreak and can maintain smooth operation of a country or region's healthcare system during a pandemic. However, large makeshift hospitals, such as the Shanghai New International Expo Center (SNIEC) makeshift hospital, which was one of the largest makeshift hospitals in the world, face two major problems: Effective and precise transfer of patients and heterogeneity of the medical care teams. Methods To solve these problems, this study presents the medical practices of the SNIEC makeshift hospital in Shanghai, China. The experiences include constructing two groups, developing a medical management protocol, implementing a multi-dimensional management mode to screen patients, transferring them effectively, and achieving homogeneous quality of medical care. To evaluate the medical practice performance of the SNIEC makeshift hospital, 41,941 infected patients were retrospectively reviewed from March 31 to May 23, 2022. Multivariate logistic regression method and a tree-augmented naive (TAN) Bayesian network mode were used. Results We identified that the three most important variables were chronic disease, age, and type of cabin, with importance values of 0.63, 0.15, and 0.11, respectively. The constructed TAN Bayesian network model had good predictive values;the overall correct rates of the model-training dataset partition and test dataset partition were 99.19 and 99.05%, respectively, and the respective values for the area under the receiver operating characteristic curve were 0.939 and 0.957. Conclusion The medical practice in the SNIEC makeshift hospital was implemented well, had good medical care performance, and could be copied worldwide as a practical intervention to fight the epidemic in China and other developing countries.

Social Media and Parental Trust for Teachers: A Qualitative Study in China

Based on WeChat, the most popular social media application in contemporary China, this ethnographical case study reveals that the development of parental trust for teachers presents as an incremental process. It derives from parents' access to information shared by teachers online, unfolds across their engaging in constant collaborations with teachers, and increases with the formation of their close affective ties with teachers. Such a process is greatly dependent upon the formation of parents' liangxin (which is typically translated in English as "conscience") in regard to teachers. This study, conducted before the COVID-19 pandemic began, indicates that social media like WeChat has turned out to be a critical agent in parents' relationship with teachers that intervenes in their meaning-making process as well as their experience of building trust towards teachers.

SARS-CoV-2 S protein triggers lung and intestinal epithelial cell damage via TGF-β/Smad2/3-mediated inflammatory cytokine production (preprint)

Background: and objective Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to ravage the world. Despite many prevention and control measures, morbidity and mortality have not decreased due to SARS-CoV-2-induced organ damage, which occur via unknown mechanisms. Methods: Primary Human small intestinal mucosa epithelial cells (HSIMECs), human colonic epithelial cells (HCoEpiCs), and human type II alveolar epithelial cells (hTIIAECs) were treated with recombinant SARS-CoV-2 S protein for 48 h. Cell morphology, permeability, and viability were detected. The expression of cysteinyl aspartate specific proteinase 3 (caspase 3) and B-cell lymphoma-2 (Bcl-2) was examined using Western blotting. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the levels of inflammatory cytokines in the supernatant. Apoptosis was observed using a Hoechst 33258 Staining Kit. SB431542 and BAY11-7082 were used to inhibit transforming growth factor-β (TGF-β)/suppressor of mothers against decapentaplegics (Smads) and the inhibitor of kappa B kinase (IKK)/nuclear factor-κB (NF-κB) pathways, respectively. Results: S protein produced no obvious changes in morphology, but decreased cell viability and increased permeability were observed in a concentration- and time-dependent manner compared to the control ( P <0.05). Apoptosis occurred with increased caspase 3 and decreased Bcl-2 ( P <0.05). S protein stimulated a disordered secretion of cytokines, including interleukin (IL)-6, IL-10, tumour necrosis factor α (TNF-α), and IL-13 ( P <0.05). Suppression of TGF-β/Smad3, but not the IKK/NF-κB, pathway relieved the damage to colon cells caused by the S protein in HSIMECs and HCoEpiCs and inhibited apoptosis mediated by TNF-α and granulocyte-macrophage colony-stimulating factor (GM-CSF) in hTIIAECs. Conclusion: The SARS-CoV-2 S protein damaged intestine and lung cells, which was associated with cytokine production and the induction of apoptosis mediated by the TGF-β/Smad3, but not the NF-κB, pathway.

Vitamin D levels and clinical outcomes of SARS-CoV-2 Omicron subvariant BA.2 in children: A longitudinal cohort study.

Objective: To investigate the picture between vitamin D levels and clinical outcomes of SARS-CoV-2 Omicron subvariant BA.2 in children. Methods: A retrospective, longitudinal cohort study was performed. All included hospitalized cases were divided into the sufficient (sVD) and insufficient vitamin D (iVD) groups according to whether their serum 25-hydroxyvitamin D [25(OH)D] concentration was ≥30 ng/mL. Dynamic changes in clinical parameters were observed for seven time periods within 28 days after admission. Results: Serum 25(OH)D concentrations were significantly negatively correlated with age in the included cases (r = -0.6; P < 0.001). Compared with the iVD group (n = 80), the sVD group (n = 36) had higher interleukin-6 (18.4 vs. 12.9; P = 0.003) within the first day; higher procalcitonin within the first (0.15 vs. 0.1; P = 0.03), 2-3 (0.14 vs. 0.07; P = 0.03), 4-5 (0.21 vs. 0.07; P = 0.02) days; more lymphocytes within the first (1.6 vs. 1.2; P = 0.02), 2-3 (3.7 vs. 2; P = 0.001), 4-5 (3.9 vs. 2.1; P = 0.01) and 6-7 (4.9 vs. 2.7; P = 0.02) days; notably, higher cycle threshold for N gene (30.6 vs 19.8; P = 0.03) or ORF1ab gene (31.4 vs 20.1; P = 0.03) within 2 to 3 days. Pneumonia lesions were found in eleven and six cases in the iVD and sVD groups, respectively, without significant difference on computed tomography at admission. Six out of eleven and five out of six had a repeat computed tomography after 1-2 weeks. Lesion improvement was more significant in the sVD group (P = 0.04). Conclusions: Children with vitamin D insufficiency might have poorer clinical outcomes in Omicron subvariant BA.2 infection, especially in older pediatric patients. Further studies are needed to assess effectiveness of supplements in reducing the same.

The strategies of "early detection, early report, early assessment, and early control" in vector prevention and control

Since the outbreak of coronavirus disease 2019 (COVID-19), the social prevention and control measures of "early detection, early report, early isolation, and early treatment" have been widely used in the public health field and are widely accepted by the general public. In the practice of integrated vector management, Henan province gives full play to the advantages of mobilization and coordination of the Patriotic Health Campaign, establishes a work path of "early detection, early report, early assessment, and early control", the strategies of "four early". It defines the responsibilities of government, departments, territories, and individuals, and clarifies the working concepts of integrated vector management, which helps to form societal forces and promote the development of vector control in Henan province. This article analyzes the strategies of "four early" in integrated vector management in Henan province, in order to provide a reference for vector management strategies in China.

Six-month follow-up of functional status in discharged patients with coronavirus disease 2019.

BACKGROUND: The long-term functional outcome of discharged patients with coronavirus disease 2019 (COVID-19) remains unresolved. We aimed to describe a 6-month follow-up of functional status of COVID-19 survivors. METHODS: We reviewed the data of COVID-19 patients who had been consecutively admitted to the Tumor Center of Union Hospital (Wuhan, China) between 15 February and 14 March 2020. We quantified a 6-month functional outcome reflecting symptoms and disability in COVID-19 survivors using a post-COVID-19 functional status scale ranging from 0 to 4 (PCFS). We examined the risk factors for the incomplete functional status defined as a PCFS > 0 at a 6-month follow-up after discharge. RESULTS: We included a total of 95 COVID-19 survivors with a median age of 62 (IQR 53-69) who had a complete functional status (PCFS grade 0) at baseline in this retrospective observational study. At 6-month follow-up, 67 (70.5%) patients had a complete functional outcome (grade 0), 9 (9.5%) had a negligible limited function (grade 1), 12 (12.6%) had a mild limited function (grade 2), 7 (7.4%) had moderate limited function (grade 3). Univariable logistic regression analysis showed a significant association between the onset symptoms of muscle or joint pain and an increased risk of incomplete function (unadjusted OR 4.06, 95% CI 1.33-12.37). This association remained after adjustment for age and admission delay (adjusted OR 3.39, 95% CI 1.06-10.81, p = 0.039). CONCLUSIONS: A small proportion of discharged COVID-19 patients may have an incomplete functional outcome at a 6-month follow-up; intervention strategies are required.

Respiratory epithelial cell responses to SARS-CoV-2 in COVID-19.

COVID-19 has different clinical stages, and effective therapy depends on the location and extent of the infection. The purpose of this review is to provide a background for understanding the progression of the disease throughout the pulmonary epithelium and discuss therapeutic options. The prime sites for infection that will be contrasted in this review are the conducting airways and the gas exchange portions of the lung. These two sites are characterised by distinct cellular composition and innate immune responses, which suggests the use of distinct therapeutic agents. In the nose, ciliated cells are the primary target cells for SARS-CoV-2 viral infection, replication and release. Infected cells shed their cilia, which disables mucociliary clearance. Evidence further points to a suppressed or incompletely activated innate immune response to SARS-CoV-2 infection in the upper airways. Asymptomatic individuals can still have a productive viral infection and infect others. In the gas exchange portion of the lung, the alveolar type II epithelial cell is the main target cell type. Cell death and marked innate immune response during infection likely contribute to alveolar damage and resultant acute respiratory distress syndrome. Alveolar infection can precipitate a hyperinflammatory state, which is the target of many therapies in severe COVID-19. Disease resolution in the lung is variable and may include scaring and long-term sequalae because the alveolar type II cells are also progenitor cells for the alveolar epithelium.

Does pre-existent physical inactivity have a role in the severity of COVID-19?

BACKGROUND AND AIMS: Physical inactivity is considered an important lifestyle factor for overweight and cardiovascular disease. We aimed to investigate the association between pre-existent physical inactivity and the risk of severe coronavirus disease 2019 (COVID-19). METHODS: We included 164 (61.8 ± 13.6 years) patients with COVID-19 who were admitted between 15 February and 14 March 2020 in this retrospective study. We evaluated the association between pre-existent physical inactivity and severe COVID-19 using a logistic regression model. RESULTS: Of 164 eligible patients with COVID-19, 103 (62.8%) were reported to be physically inactive. Univariable logistic regression analysis showed that physical inactivity was associated with an increased risk of severe COVID-19 [unadjusted odds ratio (OR) 6.53, 95% confidence interval (CI) 1.88-22.62]. In the multivariable regression analysis, physical inactivity remained significantly associated with an increased risk of severe COVID-19 (adjusted OR 4.12, 95% CI 1.12-15.14) after adjustment for age, sex, stroke, and overweight. CONCLUSION: Our data showed that pre-existent physical inactivity was associated with an increased risk of experiencing severe COVID-19. Our findings indicate that people should be encouraged to keep physically active to be at a lower risk of experiencing a severe illness when COVID-19 infection seems unpredicted.The reviews of this paper are available via the supplemental material section.

Comparison of Clinical, Laboratory and Radiological Characteristics Between COVID-19 and Adenovirus Pneumonia: A Retrospective Study.

BACKGROUND: The pandemic of coronavirus disease 2019 (COVID-19) has become a global public health problem. It is important for clinical physicians to differentiate COVID-19 from other respiratory infectious diseases caused by viruses, such as human adenovirus. SUBJECTS AND METHODS: This was a retrospective observational study. We analyzed and compared the clinical manifestations, laboratory findings and radiological features of two independent cohorts of patients diagnosed with either COVID-19 (n=36) or adenovirus pneumonia (n=18). RESULTS: COVID-19 did not show a preference in males or females, whereas 94.4% of patients with adenovirus pneumonia were males. Fever and cough were common in both COVID-19 and adenovirus pneumonia. But the median maximal body temperature of the adenovirus pneumonia cohort was significantly higher than in COVID-19 (P<0.001). Furthermore, 77.8% of patients with adenovirus pneumonia had a productive cough versus only 13.9% of COVID-19 patients (P<0.001). Compared with adenovirus pneumonia, constitutional symptoms were less common in COVID-19, including headache (16.7% vs 38.9%, P=0.072), sore throat (8.3% vs 27.8%, P=0.058), myalgia (8.3% vs 61.1%, P<0.001) and diarrhea (8.3% vs 44.4%, P=0.002). Furthermore, patients with COVID-19 were less likely to develop respiratory failure (8.3% vs 83.3%, P<0.001) and showed less prominent laboratory abnormalities, including lymphocytopenia (61.1% vs 88.9%, P=0.035), thrombocytopenia (2.8% vs 61.1%, P<0.001), elevated procalcitonin (2.8% vs 77.8%, P<0.001) and elevated C-reactive protein (36.1% vs 100%, P<0.001). Besides, a higher percentage of patients with adenovirus pneumonia showed elevated transaminase, myocardial enzymes, creatinine and D-dimer compared with COVID-19 patients. On chest CT, the COVID-19 cohort was characterized by peripherally distributed ground-glass opacity and patchy shadowing, while the adenovirus pneumonia cohort frequently presented with consolidation and pleural effusion. CONCLUSION: There were many differences between patients diagnosed with COVID-19 and those with adenovirus pneumonia in their clinical, laboratory and radiological characteristics. Compared with adenovirus pneumonia, COVID-19 patients tended to show a lower severity of illness.

Computed Tomographic Imaging of 3 Patients With Coronavirus Disease 2019 Pneumonia With Negative Virus Real-time Reverse-Transcription Polymerase Chain Reaction Test.

We reported computed tomographic (CT) imaging findings of 3 patients with coronavirus disease 2019 (COVID-19) pneumonia with initially negative results before CT examination and finally confirmed positive for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by real-time reverse-transcription polymerase chain reaction assay.