Document Type : original article


1 Baqiyatallah Research Center of Gastroenterology and Liver Disease, Baqiyatallah University of Medical Sciences, Tehran, Iran

2 Human Genetics Research center, Baqiyatallah University of Medical Sciences, Tehran, Iran

3 Department of Biology, Science and Arts University, Yazd, Iran

4 Students Research Committee, Arak University of Medical Sciences, Arak, Iran

5 Department of Research, Arka Education and Clinical Research Consultants, Tehran, Iran

6 Department of Pediatrics , Baqiyatallah University of Medical Sciences, Tehran, Iran


Background: The associations between the epidemiological, clinical, and serological features of coronavirus disease 2019 (COVID-19) and the nasopharyngeal viral load have not, yet, been understood completely.
Methods: This cross-sectional single center study of outpatient children and adolescents was conducted between January and March 2021. Reverse transcriptase polymerase chain reaction (RT-PCR) of nasopharyngeal swab specimens was positive for SARS-CoV-2. Nasopharyngeal Cycle threshold (Ct) values were measured for all patients considering different clinical features, age, and sex, in presence of covid-19 specific serum antibody.
Results: The data of 70 individuals with confirmed COVID-19 were analyzed (mean (range) age: 9.6 (5-14) years; 29 females (41%)). Sixty-four children (91.4%) were symptomatic at the time of sampling (mean time of symptom onset, 3.9 days). There were no differences in mean Ct values between the symptomatic and asymptomatic patients (31.4 vs 28.8, p=0.247). Ct values were significantly lower in cases with diarrhea (p=0.044) and younger children (p=0.003). No correlation was found between Ct values and gender (p=0.415). Serum antibody was measured in 25 (36%) patients. Presence of antibody was not associated with Ct values (p=0.121). Fifty-nine cases (84.3%) reported exposure to a SARS-CoV-2 positive household.
Conclusions: Higher nasopharyngeal Ct values, suggesting lower virus load, are related to older age, but there is no difference in Ct values between genders. Considering that diarrhea may predict lower Ct values in the respiratory system, the importance of early quarantine of children with atypical symptoms (such as gastrointestinal symptoms) or children in contact with a confirmed COVID-19 family member is highlighted


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