Rapid differential diagnosis of SARS-CoV-2, influenza A/B and respiratory syncytial viruses: Validation of a novel RT-PCR assay.

BACKGROUND: Influenza and respiratory syncytial (RSV) viruses are expected to co-circulate with SARS-CoV-2 in the upcoming seasons and clinical differential diagnosis between them is difficult. Laboratory-based RT-PCR is a gold standard diagnostic method for influenza, RSV and SARS-CoV-2. The objective of this study was to estimate the diagnostic performance of a novel point-of-care RT-PCR assay STANDARD M10 Flu/RSV/SARS-CoV-2 (SD Biosensor) in a large number of clinical specimens with diversified (co)-infection patterns and viral loads. METHODS: This was a retrospective study, in which all samples were tested in both STANDARD M10 Flu/RSV/SARS-CoV-2 index and Allplex SARS-CoV-2/Respiratory Panel 1 (Seegene) reference kits. Samples with discordant results were further processed in a third resolver test (Resp-4-Plex, Abbott). RESULTS: A total of 1,019 naso-/oropharyngeal samples (50.3% positive for at least one virus) were processed in both STANDARD M10 Flu/RSV/SARS-CoV-2 and Allplex assays and the overall between-assay agreement was as high as 94.6%. Positive percent agreement of the STANDARD M10 Flu/RSV/SARS-CoV-2 was 100%, 96.6%, 97.3% and 99.4% for influenza A, B, RSV and SARS-CoV-2, respectively. The corresponding negative percent agreement was 99.7%. 100%, 100% and 98.4%, respectively. The expected positive and negative predictive values for all viruses were constantly above 96% in a reasonable range of disease prevalence. CONCLUSIONS: STANDARD M10 Flu/RSV/SARS-CoV-2 is a reliable RT-PCR assay able to detect influenza A, influenza B, RSV and SARS-CoV-2 in one hour or less, fostering a rapid differential diagnosis of common respiratory viruses.

Evaluation of extraction-free RT-qPCR methods for SARS-CoV-2 diagnostics.

Extraction-based real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) is currently the "gold standard" in SARS-CoV-2 diagnostics. However, some extraction-free RT-qPCR techniques have recently been developed. In this study, we compared the sensitivity of traditional extraction-based, heated extraction-free, and unheated extraction-free RT-qPCR methods for SARS-CoV-2 detection in nasopharyngeal swabs from symptomatic individuals. The unheated extraction-free method showed perfect agreement with the standard extraction-based RT-qPCR. By contrast, the heat-treated technique was associated with an 8.2% false negativity rate. Unheated extraction-free RT-qPCR for the molecular diagnosis of SARS-CoV-2 is a valuable alternative to the traditional extraction-based methods and may accelerate turnaround times by about two hours.

Clinical and epidemiological characteristics of COVID-19 during the early phase of the SARS-CoV-2 pandemic: a cross-sectional study among medical school physicians and residents employed in a regional reference teaching hospital in Northern Italy.

OBJECTIVES: The aim of the study was to evaluate the clinical presentation and burden of SARS-CoV-2 infections among medical school physicians and residents, mainly young medical doctors. The awareness of COVID­19 clinical manifestations can improve the early detection of mild cases, possibly reducing further transmission to colleagues and patients. MATERIAL AND METHODS: The study was carried out in March-May 2020, involving medical school physicians in a teaching hospital in northern Italy, with a working population of 881 medical doctors. Data collection was performed using a structured form investigating clinical and epidemiological information. RESULTS: One hundred sixty-two medical doctors contacted the Occupational Health Service reporting acute respiratory symptoms or close contact exposure to a confirmed COVID­19 case. Among the confirmed COVID­19 cases, most were male doctors during residency, and 85% presented a mild clinical picture. Fever (70.3%) and cough (51.4%) represented the most prevalent symptoms of COVID­19. As revealed by the univariate analysis, the prevalence of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) positivity increased with age (OR = 1.08, 95% CI: 1.02-1.14, p = 0.012), working in a COVID­19 ward (OR = 3.33, 95% CI: 1.09-10.21, p = 0.031), presenting alteration or loss of smell/taste (OR = 10.00, 95%CI: 2.80-35.69, p < 0.001) and myalgia (OR = 3.20, 95% CI: 1.00-10.26, p = 0.046), while being a resident (OR = 0.20, 95% CI: 0.05-0.80, p = 0.030) was associated with reduced odds of being infected, compared to staff physicians. Age and loss of smell/taste were the only factors independently associated with RT-PCR positivity. CONCLUSIONS: The majority of COVID­19 cases showed a mild clinical syndrome, ranging from absence or paucity of symptoms to common cold or influenza-like symptoms. The findings of the present study increase the accuracy of the clinical diagnosis for the prompt identification and management of suspected COVID­19 cases, being particularly useful during resurges of the SARS-CoV-2 pandemic. Int J Occup Med Environ Health. 2021;34(2):189-201.

Report of Positive Placental Swabs for SARS-CoV-2 in an Asymptomatic Pregnant Woman with COVID-19.

Currently, limited data on maternal and neonatal outcomes of pregnant women with infection and pneumonia related to SARS coronavirus 2 (SARS-CoV-2) are available. Our report aims to describe a case of placental swabs positive for the molecular research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 RNA in an asymptomatic woman with positive rhino-pharyngeal swab for SARS-CoV-2 who underwent an urgent cesarean section in our obstetrics unit. Sample collection, processing, and laboratory testing were conducted in accordance with the World Health Organization (WHO) guidance. In the next months, conclusive data on obstetrical outcomes concerning the gestational age and pregnancy comorbidity as well as the eventual maternal-fetal transmission are needed.