Investigation of Factors Affecting Viral Clearance Time by Real-Time Polymerase Chain Reaction Method in Nasopharyngeal Swab Samples of COVID-19 Patients

Abstract

The coronavirus disease-2019 (COVID-19) pandemic continues to threaten the lives of millions of people. Viral shedding through the respiratory tract is the main risk factor for the transmission of the severe acute respiratory syndrome-2 (SARS-CoV-2) virus from sick individuals to healthy individuals. In this study, we aimed to investigate the viral clearance (VC) time in PCR tests of COVID-19 patients and the possible factors affecting this time. Seventy patients older than 18 years of age whose presence of SARS-CoV-2 virus was proven by real-time polymerase chain reaction (Rt-PCR) in nasopharyngeal swab samples were included in the study. The presence of SARS-CoV-2 RNA was investigated by RT-PCR in nasopharyngeal swab samples at 48-72 hour intervals, five days after the initial diagnosis. Demographic, physical examination, laboratory test, computed tomography (CT) results, concomitant diseases, and duration of VC were recorded. Of the cases, 41 were female and 29 were male. The mean age was 45.8 +/- 19.2 years. According to the CT results, in the group with no involvement, local involvement and widespread involvement, the duration of VC was 9.66 +/- 5.91 days, 9.99 +/- 4.68 days, and 10.94 +/- 5.34 days, respectively (p>0.05). While the duration of VC was determined as 8.93 +/- 4.33 days in the group without comorbidity, this period was found to be 12.26 +/- 5.69 days (p=0.025) in the group with the comorbidity. It was determined that the duration of VC was 9.55 +/- 6.37 days in women and 9.20 +/- 7.22 days in men (p=0.040). The duration of VC was found to be 10.18 +/- 7.1 days in patients over 50 years of age and 8.87 +/- 5.15 days under 50 years of age (p=0.03). A significant correlation was found between the laboratory test lactate dehydrogenase level and VC duration (p=0.007). However, a significant relationship could not be established between other laboratory test results and the duration of VC. In this retrospective observational study, the relationship between viral clearance duration in Rt-PCR and gender, age, CT results, comorbidities and laboratory results in nasopharyngeal swab samples was investigated and it was determined that the duration of VC was significantly prolonged in case of female gender, being over 50 years old and having a comorbid disease. The results obtained may contribute to predict the isolation times of the patients and to reveal the factors that may affect viral shedding.