ACKNOWLEDGEMENTS
We thank the staff at Community Vaccination Centers at Ap Lei Chau Sports Centre, Gleneagles Hospital Hong Kong, and Sun Yat-Sen Memorial Park Sports Centre. The investigators are grateful to all clinical research team members and laboratory staff of Department of Paediatrics and Adolescent Medicine of the University of Hong Kong, for their research support. We are most thankful to the study participants, as well as clinicians and laboratory staff who have provided clinical care and testing to the patients.