Table 1

Characteristics of included studies and main results

First author/journalType of studyPublication dateCountryN total populationNumber of paediatric casesAsymptomaticsSource of transmission/observations
Cao et al6
J Formosan Med Assoc		Review of reported cases26 FebruaryChina/Taiwan44 672 laboratory confirmed casesNumber of reported cases comparing with adult population was 0.9% for <10 years, and 1.2% for 10–20 yearsMost showed mild symptoms. No data on asymptomatic casesMainly intrafamiliar cluster circles. Children could become the main spreader when their infection is mild/stool could be a source of transmission
Dong et al7
Pediatrics		Epidemiology of paediatrics cases17 MarchChina/cases recruited from the China Center for Disease Control and Prevention 2143 paediatric cases reported; 34% onfirmed; 66% suspected44% asymptomaticsNot confirmed but family transmission seems to be the main source of cases
Park et al8
J Korean Med Sci		A case study. Brief report16 MarchKorea –A 10-year-old girl. First case detected in KoreaMild symptomsClose contact of her uncle and mother who were confirmed
Le et al9
Lancet Child Adolesc Health		A case study23 MarchVietnam 3-month old girl. First case of infant detected in Vietnam Nasopharyngeal swabs positiveContact with her grandmother who was confirmed
Lu et al10
New England J Med		Correspondence. Series of cases18 MarchChinaChildren treated at the Wuhan Children’s Hospital171/1391 tested were (+).15% asymptomatic. Three patients required PICU (all with previous chronic conditions)90% confirmed family cluster
Chang et al11
J Formosan Med Assoc		Systematic review of nine case series26 FebruaryChina 93 cases26% asymptomatics75% family contact
Su et al12
Emerg Microbe Infections		Series of cases12 MarchChina–9 cases from 14 families, ages 11 months to 9 yearsSix cases asymptomatics. The rest of children with mild symptoms and recovered after 2–3 weeksFamily transmission. Five discharged children were admitted again because their stool showed positive result in SARS-CoV-2 PCR.
Qiu et al13
Lancet Infec Dis		Series of cases25 MarchChinaN total=61636 cases (6%) in children.Half of them asymptomaticsFamily contact
Du et al14
Infection		Series of cases (families)23 MarchChina53 adults14 children8 out of 14 children asymptomaticAll cases family clusters
NCIRS15Reported cases from New South Wales schools.26 AprilAustralia18 cases (9 staff school members and 9 students) during March–April9 cases of students from 10 high schools and 5 primary schoolNo data863 analysed contacts of students: 1 case detected
Posfay-Barbe et al16
Pediatrics		Series of cases from Geneva University Hospital27 MaySwitzerland4710 total cases. Familial cluster evaluation40 cases (0.9%)<16 yearsOne asymptomatic8% (n=3) developed symptoms before other family members
RIVM17National Institute for Public Health and the Environment27 MayNetherlandsStudy in households: 239 participants, including 185 housemates. This involves 123 adults116 children between 1 and 16 years.No dataThere are no indications that children younger than 12 years old were the first in the family to be infected.
Heavey et al18 Euro SurveillNational Public Health Emergency28 MayIrelandStudy of school contacts of three cases on children 10–-15 years before 3 December 2020125; 222; 475 school contacts analysed, respectivelyOne case asymptomaticNo secondary school cases detected
Carlos III Public Health Institute19ENE-COVID-19 study: first wave13 MaySpainStudy of IgG antibody in a representative sample of Spanish population (N total participant population=60 897)8243 children <15 years.No data on available on symptoms stratified by agePrevalence of IgG:
<1 year=1.1% (95% CI 0.3% to 3.8%)/1–4 years=2.2% (1.4% to 3.6%)/5–9 years=3% (2.3% to 4.1%)/10–14 years = 3.9% (3.1% to 4.9%)
General population=5% (4.7% to 5.4%).

  • ENE, National study on sero-epidemiology of SARS-COV-2; NCIRS, National Centre for Immunization Research and Surveillance New South Wales; PICU, paediatric intensive care units; RIVM, National Institute for Public Health and the Environment the Netherlands; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.