Table 1:

Measures of SARS-CoV-2 infectivity in children and adults

VariableChildren aged ≤ 10 yr
n = 97		Children aged 11–17 yr
n = 78		Adults
n = 130		p value
Asymptomatic, no. (%)47 (48)19 (24)9 (7)< 0.001§
Positive culture, no. (%, 95% CI)18 (19, 11–28)18 (23, 14–34)57 (44, 35–53)< 0.001
Symptom to test time, median (IQR), d1 (1–4)2 (1–3.5)2 (1–4)0.6
Cycle threshold*, median (IQR)25.1 (17.7–31.3)22.2 (18.3–29.0)18.7 (17.9–30.4)< 0.001**
RNAseP†, mean ± SD25.7 ± 2.826.1 ± 2.626.1 ± 2.00.6
TCID50/mL‡, median (IQR)1171 (316–5620)316 (178–2125)5620 (1171–17 800)< 0.001††
Log RNA copies/mL, median (IQR)5.4 (3.5–7.8)6.4 (4.2–7.6)7.5 (5.2–8.3)< 0.001‡‡

  • Note: CI = confidence interval, IQR = interquartile range, RT-PCR = reverse transcription polymerase chain reaction, SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2, SD = standard deviation.

  • ↵* Cycle threshold is a semiquantitative measure of how much genetic material is present in the initial sample. If more RT-PCR cycles are required to detect SARS-CoV-2, then less viral RNA was present in the sample.

  • ↵† Cycle threshold values for human RNAse P gene, an endogenous internal amplification control, were used as a marker of quality of the nasopharyngeal sample.

  • ↵‡ Fifty percent tissue culture infective dose (TCID50) is a measure of infectious virus titre and represents the amount of virus required to kill 50% of cells in inoculated tissue culture.

  • ↵§ p value is < 0.001 for all comparisons: children ≤ 10 years old compared with children aged 11–17 years, children aged 11–17 compared with adults and children ≤ 10 years old compared with adults.

  • ↵ p = 0.5 children ≤ 10 years v. children aged 11–17 years; p = 0.003 children aged 11–17 years v. adults; p < 0.001 children ≤ 10 years v. adults.

  • ↵** p = 0.99 children ≤ 10 years v. children aged 11–17 years; p = 0.02 children aged 11–17 years v. adults; p < 0.001 children ≤ 10 years v. adults.

  • ↵†† p = 0.6 children ≤ 10 years v. children aged 11–17 years; p < 0.001 children aged 11–17 years v. adults; p = 0.1 children ≤ 10 years v. adults.

  • ↵‡‡ p = 0.99 children ≤ 10 years v. children aged 11–17 years; p = 0.2 children aged 11–17 years v. adults; p < 0.001 children ≤ 10 years v. adults.