Transmission dynamics of SARS-CoV-2 in children: an Indian case study

Researchers have studied the primary contacts of COVID-19 positive children in India in May 2020 and found all children to be asymptomatic, and only four of the parents became positive. Although this suggests lower transmission from children, no recommendations can be made yet on school reopening.

The number of COVID-19 cases caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) across the world has been increasing continuously. In India, the number of cases has seen a significant increase with a small dip only recently. To date, 9.67 million people have been infected nationwide and over 140,500 people have lost their lives.

Most of the studies on the spread of the virus have focused on the adult population. Less than 5% of cases are reported to be children. It is still unknown if this low number is because of children’s low susceptibility to the virus or decreased exposure. Most children who are found to be positive are seen to have only mild symptoms. A large proportion of children are also observed to be asymptomatic. This raises questions about how children transmit the disease and whether transmission from children is overall lower than the adult population.

Studying pediatric COVID-19 patients in May 2020

Researchers from Manipal Academy of Higher Education in India report the transmission dynamics of SARS-CoV-2 in children in a paper published in the Journal of Tropical Pediatrics.

During May 2020, travelers to the state of Karnataka coming from other states in India with high rates of COVID-19 had to be in institutional quarantine. Although all travelers were tested, because of resource constraints in testing, children below 18 years were prioritized. If there was a positive case, denoted as the index case, and all the family members were tested, if feasible. The parents were questioned about the health status of other non-familial contacts who traveled in the same vehicle or stayed in the same room as the index case.

The children who tested positive were admitted to the hospital and the case managed based on institutional guidelines. If the child was less than 15 years old, one of the parents stayed with them, while the other family members who tested negative continued to remain in the quarantine center. If the other family members also tested positive, they were admitted into the hospital.

The retrospective observational study included all the pediatric index cases and their primary contacts with a history of inter-state travel during May 2020. The authors included clinical and demographic information and analyzed the data after anonymizing potential patient identifiers.

Nineteen children between four and nine years old, with a median age of six years were included in the study. All the children who tested positive were asymptomatic throughout the study period. Similar to other reported studies, the SARS-CoV-2 infection of children in this study was also mild. Possible reasons for this could be a low expression of angiotensin-converting enzyme 2 in children or decreased immune response.

There were 42 familial contacts and 80 non-family contacts who traveled with the COVID-19 positive children. Of the non-family contacts, two were positive for COVID-19 and were primary contacts of one index case. Of the primary family contacts, five became positive. All except one contact was asymptomatic. It is also possible that primary family contacts of the index case were exposed to the virus via the non-family cases.

The authors write that with a similar type of exposure to the virus by a family, the children seemed more commonly positive. Even though adults stayed in the same vehicle, quarantine room, or hospital room without personal protective equipment, most parents were negative. Although it is possible that the parents were positive, but became negative by the time they were tested, since there was no previous history of exposure to an individual who tested positive or symptoms, it is likely exposure was during travel or quarantine stay.

The authors note some limitations of the study, such as its retrospective nature and the lack of multiple testing of the primary family contacts at different times to understand the time evolution of the transmission.

However, “despite the limited sample size, this study indicates children are commonly asymptomatic,” write the authors. Although there seemed to a lower rate of transmission from children, because of their susceptibility and the chance for greater transmission in closed spaces, no recommendations can be made yet for opening schools, they write. Therefore, there is a need to explore SARS-CoV-2 transmission dynamics in children further.

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