Subject recruitment and clinical characteristics
Between 1st December 2020 to 31stMarch 2021, 31 patients who had recovered from COVID-19 were recruited
from Princess Margret Hospital, Hong Kong SAR. Fourteen (45.2%) were
boys and 17 (54.8%) were girls with a median age of 12 years (range
2.7-18 years). Twenty age-matched uninfected controls were also
recruited from Queen Mary Hospital, Hong Kong SAR, China and from the
community. Subject demographics and clinical characteristics are shown
in Table 1. The majority of subjects were Chinese (80.6%). Among the
COVID-19 cases, 83.9% were domestic cases, 32.3% were asymptomatic,
and the remaining cases (67.7%) had mild disease. Blood samples were
collected at 29 to 219 days after recovery.