COVID-19 in Children: Correlation Between Epidemiologic, Clinical Characteristics, and RT-qPCR Cycle Threshold Values

Abstract

Background: Initially, the impact of SARS-CoV-2 infection on children was unknown. Standard COVID-19 diagnosis is confirmed using real-time qPCR. Cycle threshold (Ct) values of RT-qPCR are inversely proportional to viral load and the test indirectly quantifies viral RNA copy numbers. The objective of this study was to determine the correlation between epidemiology, clinical characteristics, severity of confirmed COVID-19 cases, and Ct values. Methods: An observational, analytical, cross-sectional study. All children with COVID-19 under 18 years old admitted to the Ricardo Gutiérrez Children’s Hospital between March 1, 2020, and February 28, 2021, were included. SARS-CoV-2 infection was confirmed using RT-qPCR. Results: Median age of patients was 7 years. Ct values were estimated in 419 cases, median Ct value was 23.5 [interquartile range (IQR): 18.9–30.9]. Levels were significantly lower in symptomatic than asymptomatic patients (Ct: 22.1; IQR: 18.4–22.1), in children <2 years of age (Ct: 20.6; IQR: 17.3–27.3) and when sample collection was <4 days after symptom onset (Ct: 21.1; IQR: 18.1–27.5). In children >2 years of age, Ct values were significantly lower in symptomatic (Ct: 22.6; IQR: 18.7–29.3) than asymptomatic (Ct: 31.2; IQR: 24.5–33.3) patients. Conclusions: Children younger than 2 years with COVID-19 have lower values of Ct—as a proxy for higher viral load—than older children. Symptomatic children over 2 years of age had lower Ct values compared with asymptomatic children.

SARS-CoV-2 specific antibody trajectories in mothers and infants over two months following maternal infection

“…These results concur with findings from global studies conducted during the first year of the pandemic, in which infection rates were lowest among infants and young children in communities ( 32 , 45 ) and households ( 46 – 48 ), with household secondary attack rates ranging from 5% to 55% and exhibiting marked variation across age groups ( 34 , 49 – 52 ). In an observational study of SARS-CoV-2 infected children, infants < 2 years of age were observed to have lower viral loads but lower prevalence of symptomatic cases as compared to children 2 years and older ( 53 ). We observed a slightly higher prevalence of PCR positivity and symptomatic cases among infants as compared to other household children aged 2-5 years in our study, though differences in PCR positivity may reflect age-related differences in exposures related to care and feeding, testing, and parental perception of symptoms and risks that influenced testing.…”

Clinical utility of SARS-CoV-2 subgenomic RT-PCR in a pediatric quaternary care setting

“…Moreover, Gentile et al. report lower CT values in children <2 compared to those age 2–17 [22] . Jiménez et al.…”

SARS-CoV-2 Variants of Concern: Presumptive Identification via Sanger Sequencing Analysis of the Receptor Binding Domain (RBD) Region of the S Gene

“…The need for a high viral load seems not to pose a problem, as most of the Ct values in symptomatic SARS-CoV-2-positive patients are lower than 20, especially when the clinical samples are collected within 10 days since symptom onset [ 23 , 24 ]. Moreover, the high viral load does not prevent performance of the test, as greater risk of transmission, as in an outbreak scenario, is associated with increased viral load values and positive relationships between viral load and infectiousness [ 25 ].…”