Sri Lanka College of Paediatricians, Family Health Bureau and

World Health Organisation (WHO)- Sri Lanka

2. COVID-19 In Children

2.1 Incidence:
Compared to adults, the number of cases and proportion of severe COVID-19 disease among children is significantly low. In most instances, the proportion of childhood cases are approximately 10% or less of all COVID-19 positive patients. However, with the acute surge of the total number of cases, the number of reported cases among children has risen. Therefore, a high possibility of children with severe disease is also expected, along with the increased number. Following hypotheses have been proposed on why children are less susceptible to acquire COVID-19 infection or develop severe disease compared to adults.
  • Differences in the number and the distribution of ACE2 receptors and their affinity to SARS CoV-2
  • Differences in the endothelium and clotting function (make children less susceptible to developing endothelial damage, activation of coagulation pathways, and formation of microthrombi).
  • The presence of more cross-reactive and neutralizing antibodies after infections with other coronaviruses in children. In contrast, adults have more non-neutralizing antibodies that lead to antibody-dependent enhancement.
  • Strong and protective innate immune response in children compared to immunosenescence and dysfunctional or over-active innate immune response in adults.
  • Differences in the microbiota (oropharyngeal, nasopharyngeal, lung, and gastrointestinal)
  • Higher levels of melatonin which has anti-inflammatory and anti-oxidative properties
  • Lower prevalence of comorbidities that leads to severe disease
  • Less intense exposure to SARS-CoV-2 in children due to less social mobilization.
2.2 Modes of transmission:
  • Droplet transmission
  • Contact transmission
  • Airborne transmission: Consistent and robust evidence is emerging about the possibility of SARS-CoV-2 spreads by airborne transmission. This is particularly important in accelerating transmission within closed spaces with poor ventilation, but it does not mean that the virus can spread long distances through the air.
2.3 Incubation period:
Data on the exact incubation period in children is limited. Generally, the median incubation period is five days but may extend up to 14 days.  Usually, children develop symptoms 2-10 days after exposure.