Two separate studies of pediatric patients in Wuhan, China found that though clinical manifestations of the coronavirus disease 2019 (COVID-19) in children were less severe than those of adult patients, young children, particularly infants, were vulnerable to the infection.1-2
“Why most of the children’s COVID-19 cases were less severe than adults’ cases is puzzling. This may be related to both exposure and host factors,” the authors of the first study wrote.1 “These results suggest that young children, particularly infants, were vulnerable to [COVID-19] infection. Therefore, the mechanisms for the difference in clinical manifestations between children and adults remain to be determined.”
The first study, published in Pediatrics, looked at a nationwide case series of 2,143 pediatric patients with COVID-19 reported to the Chinese Center for Disease Control and Prevention from January 16 to February 8, 2020. The median age of all patients was 7 years (interquartile range, 2-13) and 1,213 cases (56.6%) were boys.
Overall, they found 731 (34.1%) laboratory-confirmed cases and 1,412 (65.9%) suspected cases. Moreover, over 90% of all of the patients were asymptomatic, mild, or moderate cases. The median time from illness onset to diagnoses was 2 days (range, 0-42), and there was a rapid increase of disease at the early stage of the epidemic followed by a gradual and steady decrease.
The proportion of severe and critical cases was 10.6%, 7.3%, 4.2%, 4.1%, and 3.0% for the age group of ˂1, 1-5, 6-10, 11-15 and >15 years, respectively. Additionally, there were more severe and critical cases in the suspected than confirmed category, though it remains to be determined whether the severe and critical cases in the suspected group were caused by COVID-19 or other pathogens.
“The results of this study provide strong evidence for human-to-human transmission as children were unlikely to visit the Huanan Seafood Wholesale Market where the early adult patients were reported to obtain [COVID-19],” the authors wrote. “To gain a better understanding of children’s COVID-19, more detailed patient information, particularly clinical outcomes (e.g., discharge, transferred to intensive care unit, or death), should be collected in future studies.”
In the second study, published in JAMA Network, researchers identified 9 hospitalized infants infected with COVID-19 between December 8, 2019 and February 6, 2020.2 Seven of the patients were female, and the youngest was 1 month and the oldest was 11 months.
Overall, 4 patients were reported to have a fever, 2 had mild upper respiratory tract symptoms, 1 had no symptoms but tested positive due to exposure to infected family members, and 2 had no information on symptoms available. The time between admission and diagnosis was 1-3 days.
Each of the 9 infants were found to have at least 1 family member who was infected, with the infant’s infection occurring after the family member’s infection. Moreover, 7 of the infants were reported to be either living in Wuhan or having family members who visited Wuhan, 1 had no direct linkage to Wuhan, and 1 had no information available. None of the infants required intensive care or mechanical ventilation or had any severe complications.
Though the number of infants identified was small, the researchers suggested that this may be due to a lower risk of exposure or incomplete identification due to mild or asymptomatic disease, rather than resistance to infection. Further, infants who have infected family members should be monitored or evaluated and family clustering should be reported to ensure a timely diagnosis.
“Because infants younger than 1 year cannot wear masks, they require specific protective measures,” the authors wrote. “Adult caretakers should wear masks, wash hands before close contact with infants, and sterilize the infants’ toys and tableware regularly.”
1. Dong Y, Mo X, Hu Y, et al. Epidemiological Characteristics of 2143 Pediatric Patients with 2019 Coronavirus Disease in China. Pediatrics. doi:10.1542/peds.2020-0702.
2. Wei M, Yuan J, Liu Y, et al. Novel Coronavirus Infection in Hospitalized Infants Under 1 Year of Age in China. JAMA. doi:10.1001/jama.2020.2131.