Young children may be silent carriers of SARS-CoV-2

Experts from the Chinese University of Hong Kong (CUHK) have found that young children may be a potential source of contagion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) despite being asymptomatic. In young children, stool test is more feasible than sputum, deep-throat saliva or nasopharyngeal test for coronavirus disease 2019 (COVID-19) case detection to break the chains of COVID-19 transmission.

“As of 25 March 2021, a total of 11,429 cases of COVID-19 had been diagnosed in Hong Kong. Among all the cases diagnosed, 929 cases [8.1 percent] were children aged ≤17 years, of which 21.6 percent [n=201] of cases were toddlers aged ≤3 years,” said Professor Siew-Chien Ng of the Centre for Gut Microbiota Research, CUHK.  

“Importantly, 43.3 percent [n=87] of cases aged ≤3 years were asymptomatic and may potentially transmit COVID-19 in the community whilst being undetected,” pointed out Ng.

“While measures are undertaken to prevent the spread of COVID-19 in high-risk individuals, an appropriate strategy for preventing potential transmission between children and families should be designed to minimize unfavourable outcome in young children,” she suggested.

In the Massachusetts General Hospital Paediatric COVID-19 biospecimen repository study (n=192; mean age, 10.2 years), children in the asymptomatic or early phase of infection (ie, day 2 of symptoms) were found to have significantly higher SARS-CoV-2 viral load in nasopharyngeal swabs compared with adults requiring intubation for severe SARS-CoV-2 infection. In the study, 26 percent (n=29) of children were diagnosed with acute SARS-CoV-2 infection and 9 percent (n=18) had multisystem inflammatory syndrome in children (MIS-C), defined as fever >38°C for >24 hours, laboratory evidence of inflammation, ≥2 organs involved, no alternative plausible diagnoses, and a positive SARS-CoV-2 test by real-time polymerase chain reaction test, serology or antigen test. [J Pediatr 2020;227:45-52]

“As of 25 March 2021, 17,500 stool screening tests for COVID-19 had been conducted by CUHK since establishment of the service in late March 2020, with 22 confirmed cases detected [detection rate, 0.13 percent],” said Professor Paul Kay-Sheung Chan of the Department of Microbiology, CUHK.

“Of note, children aged ≤6 years and asymptomatic SARS-CoV-2 carriers accounted for >90 percent and >70 percent of the confirmed cases, respectively,” he pointed out. “We should stay vigilant of individuals in this age group as our data show that despite being asymptomatic, children may be a potential source of contagion of SARS-CoV-2 infection in the community, with high SARS-CoV-2 viral load, live viruses detected in 90 percent of stool samples, and extended incubation periods [up to 36 days in one of the cases].”

“Stool test provides an accurate, safe and effective option for COVID-19 screening, especially for the paediatric population who may have difficulty in providing respiratory samples through sputum, deep-throat saliva or nasopharyngeal swabs,” he suggested.

“Fever, cough and rhinorrhea are commonly reported in paediatric patients with COVID-19. Medical attention and COVID-19 stool screening test are recommended particularly for children who feel unwell after visiting high-risk areas, those residing in buildings subject to compulsory testing, or in case of reported sickness of unknown cause among school personnel and students, in order to break the chains of COVID-19 transmission,” said Professor Albert Martin Li of the Department of Paediatrics, CUHK.