Virological Characteristics of Hospitalized Children With SARS-CoV-2 Infection

Abstract

Background and objectives: In children with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, virological characteristics and correlation with disease severity have not been extensively studied. The primary objective in this study is to determine the correlation between SARS-CoV-2 viral load (VL) in infected children with age, disease severity, and underlying comorbidities.

Methods: Children <21 years, screened for SARS-CoV-2 at the time of hospitalization, who tested positive by polymerase chain reaction were included in this study. VL at different sites was determined and compared between groups.

Results: Of the 102 children included in this study, 44% of the cohort had asymptomatic infection, and children with >1 comorbidity were the most at risk for severe disease. VL in children with symptomatic infection was significantly higher than in children with asymptomatic infection (3.0 × 10⁵ vs 7.2 × 10³ copies per mL; P = .001). VL in the respiratory tract was significantly higher in children <1 year, compared with older children (3.3 × 10⁷ vs 1.3 × 10⁴ copies per mL respectively; P < .0001), despite most infants presenting with milder illness. Besides the respiratory tract, SARS-CoV-2 RNA was also detectable in samples from the gastrointestinal tract (saliva and rectum) and blood. In 13 children for whom data on duration of polymerase chain reaction positivity was available, 12 of 13 tested positive 2 weeks after initial diagnosis, and 6 of 13 continued to test positive 4 weeks after initial diagnosis.

Conclusions: In hospitalized children with SARS-CoV-2, those with >1 comorbid condition experienced severe disease. SARS-CoV-2 VL in the respiratory tract is significantly higher in children with symptomatic disease and children <1 year of age.

FIGURE 1

Correlation between Ct and VL. There was a strong inverse correlation between Ct value and VL loads in samples obtained from children with COVID-19 (r = −1).

FIGURE 2

Nasopharyngeal VL comparison by age. A, VL comparison in children on the basis of age revealed significantly higher VL levels in children ≤1 of age, compared with children 1 to 5 (P = .01), 6 to 17 (P = .0002), or 18 to 21 (P = .001) years of age. The midlines represent medians, and the boxes represent interquartile ranges. The whiskers represent data points within the fifth to 95th percentile for the group. B, VL comparison between children <1 year of age and those 1 to 21 years of age revealed significantly higher VLs in children <1 year of age (P < .0001). The symbols for each group represent medians, and the whiskers represent 95% confidence intervals.

FIGURE 3

Nasopharyngeal swab VL comparison by disease severity. A, Children with symptomatic infection had significantly higher VLs than those with asymptomatic infection (P = .001). The symbols represent medians, and the whiskers represent 95% confidence intervals. B, Children with either mild or moderate-severe infection were noted to have higher VL levels, compared with children with asymptomatic infection. There was no significant difference in VL levels between mild and moderate-severe disease (P = .9). The midlines represent medians, and the boxes represent 95% confidence intervals. The whiskers represent the fifth to 95th percentile for the group, and outliers are represented by circles.

FIGURE 4

Nasopharyngeal VL comparison by underlying comorbidities. Nasopharyngeal VL comparison between groups with 0, 1, or >1 underlying comorbid conditions did not reveal a significant difference between groups (P = .8). The midlines represent medians, and the boxes represent 95% confidence intervals. The whiskers represent the fifth to 95th percentile for the group, and outliers are represented by circles.

FIGURE 5

VL comparison by site of detection. Comparison of VL at different sites did not reveal a significant difference between sites. The midlines represent medians, and the boxes represent 95% confidence intervals. The whiskers represent the fifth to 95th percentile for the group, and outliers are represented by circles.

FIGURE 6

Correlation between respiratory and gastrointestinal samples. A, VL comparison between paired nasopharyngeal and nasal swabs. B, VL comparison between paired NP and saliva swabs. C, VL comparison between paired NP and rectal swabs. D, VL comparison between paired saliva and rectal swabs.