Assessment of SARS-CoV-2 viral loads in combined nasal-and-throat swabs collected from COVID-19 individuals under the Universal Community Testing Programme in Hong Kong.

BACKGROUND: Combined nasal-and-throat swabs (CNTS) is less invasive and easy to execute. CNTS also induces lower risk to healthcare workers upon collection. However, there is a lack of data on viral load assessment for population-wide testing. OBJECTIVE: This study assessed if CNTS is suitable as an alternative specimen type for the detection of SARS-CoV-2. METHODS: We assessed the viral load of SARS-CoV-2 in CNTS collected from COVID-19 individuals through the 2-week period of the Universal Community Testing Programme (UCTP) conducted in Hong Kong. In addition, we compared viral loads of SARS-CoV-2 for the paired CNTS and non-CNTS specimens among these individuals. RESULTS: This UCTP identified 48 COVID-19 individuals from nearly 2 million specimens collected. The viral loads of SARS-CoV-2 varied widely, cycle threshold values Ct 16.28-36.94, among symptoms and asymptomatic individuals. The viral loads for the paired CNTS and non-CNTS specimens were comparable. CONCLUSIONS: This study demonstrated that CNTS could be a specimen of choice for diagnosis of SARS-CoV-2.

[Hospital inhouse contact tracing-significant impact to patient care during the coronavirus pandemic]. / Krankenhausinterne Kontaktpersonennachverfolgung ­ Ein wichtiger Beitrag zur Sicherstellung der Patientenversorgung in der SARS-CoV-2-Pandemie.

BACKGROUND: As part of the SARS-CoV­2 pandemic, the district of Heinsberg developed into an infectiological epicentre for Germany in February 2020. Our hospital, which is located in the immediate vicinity, reacted very quickly in addition to adapting patient care by implementing an organizational structure for recording SARS-CoV-2-positive employees, patients and their contact persons. OBJECTIVES: The infections recorded in contact tracing were analysed and, based on an exemplary outbreak, infection chains and follow-up processes were evaluated. MATERIAL AND METHODS: Comprehensive data on contact types, oropharyngeal swab results for SARS-CoV­2 and quarantine days were documented and retrospectively evaluated using a self-developed database. RESULTS: Of the 568 employees recorded by in-house contact tracing, 32 employees (1.2%, n = 2567) were detected as SARS-CoV­2 positive. Of those, 50% (n = 16) tested positive due to contact tracing, 15.6% (n = 5) were recorded by routine smears and 34.4% (n = 11) were returning travellers. The variable PCR results of the control smears from these positive employees were noticeable. In 18.8% (n = 6) of the initially negative control smears, positive PCR results were found in the following control smear. The inhouse contact tracing team was able to detect infection clusters on non-COVID-19 wards at an early stage and, together with clinical hygiene and the public health department, initiated comprehensive measures to limit the spread of the virus. Infection chains could thus be interrupted. CONCLUSION: The work of the clinic's own contact tracing unit has proven to be an essential part of clinical pandemic management not least against the background of new waves of infection and is indispensable for the detection of local infection clusters.

Dynamic changes of throat swabs RNA and serum antibodies for SARS-CoV-2 and their diagnostic performances in patients with COVID-19.

Dynamic changes of RNA and antibodies in SARS-CoV-2 infected patients remain largely unknown, and influence factors for antibody production have not been fully clarified. In this study, consecutive throat swabs specimens (n = 1875) from 187 patients were collected to analyse the dynamic changes of RNA. Moreover, 162 serial serum samples from 31 patients were tested for seroconversion of IgM and IgG. Meanwhile, IgM and IgG were also detected in 409 COVID-19 patients and 389 controls. Additionally, the logistic regression analysis was executed to identify the possible influence factors for antibody production. The median positive conversion time for RNA was day 7 (IQR, 3-11), and the positive rate was highest in day 1-5 (74.59 %) and then gradually decreased. The median time of seroconversion for IgM and IgG were both day 12 (IQR, 10-15). The sensitivity and specificity for IgM (or IgG) was 87.04% and 96.92%, respectively. Multivariate logistic regression indicated that reduced lymphocytes and short positive conversion time for SARS-CoV-2 RNA were independent factors for negative results of IgM and IgG. In conclusion, RNA and antibodies should be combined for COVID-19 diagnosis, and delayed seroconversion was influenced by the decreased lymphocytes and short positive conversion time for RNA.

Effects of Different Temperature and Time Durations of Virus Inactivation on Results of Real-time Fluorescence PCR Testing of COVID-19 Viruses.

The novel Coronavirus SARS-CoV-2 caused an outbreak of pneumonia in Wuhan, Hubei province of China in January 2020. This study aims to investigate the effects of different temperature and time durations of virus inactivation on the results of PCR testing for SARS-CoV-2. Twelve patients at the Renmin Hospital of Wuhan University suspected of being infected with SARS-CoV-2 were selected on February 13, 2020 and throat swabs were taken. The swabs were stored at room temperature (20-25°C), then divided into aliquots and subjected to different temperature for different periods in order to inactivate the viruses (56°C for 30, 45, 60 min; 65, 70, 80°C for 10, 15, 20 min). Control aliquots were stored at room temperature for 60 min. Then all aliquots were tested in a real-time fluorescence PCR using primers against SARS-CoV-2. Regardless of inactivation temperature and time, 7 of 12 cases (58.3%) tested were positive for SARS-CoV-2 by PCR, and cycle threshold values were similar. These results suggest that virus inactivation parameters exert minimal influence on PCR test results. Inactivation at 65°C for 10 min may be sufficient to ensure safe, reliable testing.

Comparison of throat swabs and sputum specimens for viral nucleic acid detection in 52 cases of novel coronavirus (SARS-Cov-2)-infected pneumonia (COVID-19).

Objectives In December 2019, a novel coronavirus (SARS-CoV-2)-infected pneumonia (COVID-19) occurred in Wuhan, China. Laboratory-based diagnostic tests utilized real-time reverse transcriptase polymerase chain reaction (RT-PCR) on throat samples. This study evaluated the diagnostic value to analyzing throat and sputum samples in order to improve accuracy and detection efficiency. Methods Paired specimens of throat swabs and sputum were obtained from 54 cases, and RNA was extracted and tested for 2019-nCoV (equated with SARS-CoV-2) by the RT-PCR assay. Results The positive rates of 2019-nCoV from sputum specimens and throat swabs were 76.9% and 44.2%, respectively. Sputum specimens showed a significantly higher positive rate than throat swabs in detecting viral nucleic acid using the RT-PCR assay (p = 0.001). Conclusions The detection rates of 2019-nCoV from sputum specimens were significantly higher than those from throat swabs. We suggest that sputum would benefit for the detection of 2019-nCoV in patients who produce sputum. The results can facilitate the selection of specimens and increase the accuracy of diagnosis.