Epidemiological burden of parents being the index cases of COVID-19 infected children

Table 1 Salient features of the reviewed studies

Ref.	Country	Continent	Study design	Study period (2020)	Inclusion criteria	COVID-19 diagnosis confirmation in children	Age of COVID-19 infected children with index case	No. of COVID-19 infected children with index case		COVID-19 infected index case/s’
								Parent	Not-parent1	Age	COVID-19 diagnosis Ascertainment	Symptoms around the time of contact with children	Death due to COVID-192
Götzinger et al[15], 2020	21 European nations except France3	Europe	Case series	1 Apr-24 Apr	≤ 18 yr SARS-CoV-2 infected individuals	RT-PCR	Median age 5·yr (IQR 5–12)	324	24 (sibling); 234 (immediate family member or unknown)	Unclear	History	Unclear	Unclear
Kim et al[16], 2020	South Korea	Asia	Cross-sectional	20 Jan- 6 Apr	≤ 18 yr SARS-CoV-2 infected individuals	RT-PCR	15 yr	0	1 (sibling)	16 yr	RT-PCR	Symptomatic	No
								0	1 [unknown (not parent or sibling)]	Unclear	Unclear	Unclear	Unclear
Luo et al[20], 2020	China	Asia	Case report	NA	NA	RT-PCR	Average 7 yr	2	0	39 yr	RT-PCR	Symptomatic	No
Merza et al[21], 2020	Iraq	Asia	Case series	18 Mar-07 April	Hospitalized conformed COVID-19 cases	RT-PCR	Average 11 yr	3	0	45 yr	RT-PCR	Symptomatic	No
Silva et al[22], 2020	Brazil	South America	Descriptive report	NA	NA	Rapid test	Average 10.5 yr	2	0	2 index cases: Male: 51 yr; female: 42 yr	RT-PCR	Symptomatic (both)	No
Song et al[23], 2020	China	Asia	Descriptive report	NA	NA	RT-PCR	Average 3.94 yr	5	0	Parents (n = 3): Average age 40.33 yr	RT-PCR	Symptomatic	No
								0	2 (grandparent)	Grandparent (n = 1): 60 yr		Symptomatic	No
Torres et al[24], 2020	Chile	South America	Cross-sectional	NA	All school staff and randomly selected students	RT-PCR	Unclear	0	7 (school staff)	Unclear	RT-PCR	Unclear	Unclear
Yang et al[25], 2020	Taiwan	Asia	Descriptive report	NA	NA	RT-PCR	11 yr	0	1 (grandparent)	85 yr	RT-PCR	Symptomatic	Yes
Yung et al[26], 2020	Singapore	Asia	Case series	5 Mar–30 Apr	Paediatric household contacts of confirmed COVID-19 cases	RT-PCR	Unclear	74	2 (grandparent or another adult except parent)5	Unclear	RT-PCR	Unclear	Unclear
Zhang et al[27], 2020	China	Asia	Research letter	28 Jan–15 Mar	Secondary COVID-19 cases	RT-PCR	Average 3 yr	2	0	Unclear	RT-PCR	One case: Mild symptoms. Other case: Moderate symptom	Unclear
Danis et al[17], 2020	France	Asia	Descriptive report	NA	NA	RT-PCR	9 yr	0	1 (a visitor/tourist)	Unclear	RT-PCR	Yes	No
James et al[18], 2020	United States	North America	Descriptive report	NA	NA	RT-PCR	≤ 18 yr	0	2 (a pastor and his wife)	Two index cases aged 56 and 57 yr	RT-PCR	During contact: Initially asymptomatic, then symptomatic	No
Jung et al[19], 2020	South Korea	Asia	Research letter	NA	NA	RT-PCR	Average 5.5 yr	1	0	The mother: 40 yr	RT-PCR	During contact asymptomatic (symptomatic after RT-PCR diagnosis)	No
								0	1 (another patient who stayed in the same room)	For 9 years old: Unclear	Unclear	Unclear	Unclear

¹In parenthesis the COVID-19 infected child/children’s relation to the index case.

²Upto the time period for which index case data reported or at the time of contact–whichever reported in the reviewed studies.

³Austria, Belgium, Bulgaria, Croatia, Denmark, Estonia, Germany, Greece, Hungary, Ireland, Italy, Lithuania, Norway, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, and the United Kingdom.

⁴Either mother or father the index case; another non-parent may be an index case for some of the children.

⁵May also have a parent index case. RT-PCR: Reverse transcription polymerase chain reaction; SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2; NA: Not applicable; COVID-19: Coronavirus disease 2019.