ABSTRACT
Objective: This study aimed to determine the duration of SARS-CoV-2 clearance in persons in Ghana. The research question was whether the duration of virus clearance in Ghana matched the 14 days recommended by the World Health Organization (WHO); this had direct implications for transmission, which was key in managing the COVID-19 pandemic. Design: This was a retrospective analytical study. Setting: All facilities that submitted clinical specimens to Noguchi Memorial Institute for Medical Research (NMIMR) for SARS-CoV-2 diagnosis between March to June 2020 were included in the study. Interventions: Samples from 480 persons who tested positive for SARS-CoV-2 by RT-PCR from March to June 2020 at NMIMR and submitted at least two follow-up samples were retrospectively analysed. Individuals with two consecutive negative RT-PCR retesting results were considered to have cleared SARS-CoV-2. Results: The median time from the initial positive test to virus clearance was 20 days (IQR: 5-56 days). This was six days longer than the WHO-recommended 14 days, after which infected persons could be de-isolated. Sputum and nasopharyngeal swabs proved more sensitive for detecting viral RNA as the infection progressed. At a significance level of 0.05, age and sex did not seem to influence the time to SARS-CoV-2 clearance. Conclusions: The median time to SARS-CoV-2 clearance in this study was 20 days, suggesting that SARS-CoV-2 infected persons in Ghana take longer to clear the virus. This finding calls for further investigations into whether patients who remain PCR positive continue to be infectious and inform isolation practices in Ghana.
Subject(s)
Humans , Male , Female , Signs and Symptoms , Middle East Respiratory Syndrome Coronavirus , SARS-CoV-2 , COVID-19 , COVID-19 Nucleic Acid TestingABSTRACT
Resumen Introducción: La pandemia de COVID-19 ha afectado a millones de personas en todo el mundo. La identificación de sujetos infectados ha sido importante para el control. Objetivo: Evaluar el rendimiento de una reacción de polimerasa en cadena (RPC) cuantitativa en tiempo real (en inglés: RT-qPCR) para SARS-CoV-2, utilizando saliva como matriz en comparación con un hisopado nasofaríngeo (HNF). Metodología: Se reclutaron adultos en atención ambulatoria, la mayoría sintomáticos. Fueron estudiadas 530 muestras pareadas de saliva e HNF con RT-qPCR. Resultados: Fueron positivas 59 muestras de HNF y 54 de saliva. La sensibilidad con saliva fue 91%, especificidad 100%, el valor predictor positivo (VPP) 100%, valor predictor negativo (VPN) 98%. El índice Kappa fue de 0,95 y LR-0,08. En promedio, el umbral de ciclo (en inglés cycle threshold-CT) de la saliva fue 3,99 puntos más alto que los de HNF (p < 0,0001) mostrando que la carga viral (CV) es menor en saliva. La carga viral en ambas disminuyó con el tiempo después del inicio de los síntomas. El muestreo de saliva fue preferido por los sujetos en lugar de HNF. Conclusión: Este estudio demuestra que la RPC para SARS-CoV-2 utilizando saliva, es adecuada para el diagnóstico de COVID-19 en adultos ambulatorios, especialmente en la etapa temprana de los síntomas.
Abstract Background: The COVID-19 pandemic has affected millions of people around the world. Part of control strategies is testing a large proportion of the population to identify and isolate the infected subjects. Aim: To evaluate the SARS-CoV-2 detection by the performance of a reverse transcription and quantitative polymerase chain reaction (RT-qPCR) against SARS-CoV-2, using saliva as a matrix compared to a nasopharyngeal swab (NPS) to simplify obtaining a diagnostic sample. Methods: Adults in outpatient care were recruited, 95% of them symptomatic. We studied 530 paired saliva and NPS samples by SARS-CoV-2 RT-qPCR. Results: Fifty-nine individuals tested positive in NPS and 54 in saliva samples. Sensitivity for saliva sample was 91%, specificity 100%, positive predictive value (PPV) 100%, negative predictive value (NPV) 98%. The Kappa index was 0.95 and LR-0.08. On average, the cycle threshold (CT) of saliva was 3.99 points higher than those of NPS (p < 0.0001) showing that viral load (VL) is lower in saliva than in NPS. Viral load in both decreased over the time after onset of symptoms. Saliva sampling was preferred by subjects instead of NPS. Conclusion: This study demonstrates that SARS-CoV-2 RT-qPCR using saliva, even with lower VL, is suitable for the diagnosis of COVID-19 in outpatient adults, especially at early stage of symptoms.