Related Experiment Video
Updated: Nov 14, 2025
Reverse Genetics to Engineer Positive-Sense RNA Virus Variants
Published on: June 9, 2022
Viral Clearance Course of COVID-19 Outbreaks
Shaher M Samrah1, Abdel-Hameed Al-Mistarehi2, Tariq Kewan3
1Department of Internal Medicine, Faculty of Medicine, Jordan University of Science and Technology, Irbid, Jordan.
Insights
COVID-19 viral clearance can extend beyond symptom resolution, with positive tests occurring up to 20 days after symptoms improve. Continued public health measures like masking and hygiene are vital for controlling coronavirus disease 2019 transmission.
Area of Science:
- Infectious Diseases
- Virology
- Public Health
Background:
- Coronavirus disease 2019 (COVID-19) presents an unpredictable clinical course.
- Understanding viral shedding and clearance is crucial for managing the pandemic.
Purpose of the Study:
- To describe the incubation period and viral clearance time (VCT) in hospitalized COVID-19 patients in Northern Jordan.
- To identify predictors of prolonged viral clearance in COVID-19.
Main Methods:
- Retrospective analysis of 157 hospitalized COVID-19 cases from March 15 to June 09, 2020.
- RT-PCR testing every two days to determine viral cure (two negative tests ≥ 24 hours apart).
- VCT defined as time from first positive swab to first of two consecutive negative tests.
Main Results:
- Median incubation period was 6 days (range 1-17 days).
- Median VCT was 13 days (range 1-40 days); symptomatic cases and abnormal chest X-rays predicted longer VCT.
- Most symptomatic cases (91.7%) remained RT-PCR positive for up to 20 days post-symptom resolution.
Conclusions:
- Viral cure often lags significantly behind symptom resolution in COVID-19 patients.
- Sustained public health interventions (social distancing, hygiene, masking) are recommended even after clinical recovery to prevent further transmission.
Background:
Coronavirus disease 2019 (COVID-19) viral course and behavior remain unpredictable. This study describes incubation time and viral clearance of COVID-19 hospitalized cases in Northern Jordan.
Methods:
All COVID-19 confirmed cases hospitalized from March 15 to June 09, 2020, were included. Nasopharyngeal swabs were collected, and COVID-19 reverse transcription-polymerase chain reaction (RT-PCR) was performed every two days in all cases. The viral cure was defined when two negative RT-PCR tests were obtained ≥ 24 hours apart. Viral clearance time (VCT) reflects the time from the first positive nasopharyngeal swab to the first of two consecutive negative tests.
Results:
In this cohort, a total of 157 patients were included. Most cases resulted from two major outbreaks. The median incubation period was 6 days (IQR, 3-10) and ranged from 1 to 17 days. The median VCT was 13 days (IQR, 7-2) and ranged from 1 to 40 days. Symptomatic presentation and abnormal chest radiograph were predictors for a prolonged VCT (p=0.015 and p=0.014, respectively). The median time of resolution of symptoms was 7 days (IQR, 3-10 days). Most symptomatic cases (91.7%) remained RT-PCR positive for up to 20 days after symptoms resolution, with a median of 13.5 days. VCT significantly correlated with the incubation period (p=0.013).
Conclusion:
Viral cure lagged for as long as 20 days after resolution of symptoms. Continuing with social-distancing, frequent hand hygiene, and wearing facial mask remains essential and is recommended even after clinical resolution of symptoms.
Related Concept Videos
01:18Steps in Outbreak Investigation
01:29Subviral Agents
01:20Viral Replication: Lytic Cycle
01:17Transmission-based Precautions I: Contact, Enteric, and Droplets
Contact Precautions:
Contact precautions are the measures taken to prevent the transmission of infectious agents, especially epidemiologically important microorganisms such as MRSA or influenza, primarily transmitted through direct or indirect contact with an...