Objectives To assess the reactogenicity, measure the adaptive immune responses and track the long-term immune memory in healthy children and adults as well as pediatric patients receiving the COVID-19 vaccines-BNT162b2, CoronaVac-chosen by the Hong Kong Government; to compare the reactogenicity and immunogenicity across the vaccines used for these children and adults. Hypothesis to be tested The safety profile and the magnitude and durability of immune responses to the COVID-19 vaccines in children are non-inferior to those in adults. Design and subjects A single-site, comparative nonrandomised clinical trial for 450 healthy individuals or patients under 18 years old and one or both healthy parents and unrelated adults to receive one of COVID-19 vaccines by intramuscular injection (and intradermal injection) Instruments Mobile app for subjects to record adverse effects, enzyme-linked immunosorbent assay, plaque reduction neutralization assay, luciferase immunoprecipitation system assay and flow cytometry. Interventions BNT162b2 and CoronaVac, by intramuscular or intradermal route Main outcome measures Types and frequencies of adverse effects within 7 days, and changes and peaks of antibody levels and antigen-specific memory T cell responses for 3 years.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
1,018
mRNA vaccine developed by BioNTech against COVID-19
Inactivated virus vaccine developed by SinoVac against COVID-19, intramuscular
Inactivated virus vaccine developed by SinoVac against COVID-19, intradermal
Queen Mary Hospital
Hong Kong, Hong Kong, China
Adverse reactions
Percentage of occurrence, types, duration and severity of adverse reactions occurring within 7 days
Time frame: 7 days post-doses 1, 2 and 3 (and 4)
Binding antibody response
Geometric mean levels of SARS-CoV2 S and S-RBD-specific binding antibody and related markers as determined by Enzyme-linked Immunosorbent Assay
Time frame: 1 month post-dose 1, and 1, 6, 18, and 36 months post-dose 3 (and 2 weeks after dose 4)
Neutralizing antibody response
Geometric mean levels and geometric mean fold rise of SARS-CoV2 neutralizing antibodies as determined by plaque reduction neutralization assay and surrogate assays
Time frame: 1 month post-dose 1, and 1, 6, 18, and 36 months post-dose 3 (and 2 weeks after dose 4)
T cell response
Geometric mean percentage of CD4 and CD8 T cells specific to SARS-CoV2 S (and N and M) protein
Time frame: 1 month post-dose 1, and 1, 6, 18, and 36 months post-dose 3 (and 2 weeks after dose 4)
Vaccine breakthrough
Incidence of COVID-19 in participants throughout study period as self-reported or as determined by Luciferase Immunoprecipitation Systems assay/ELISA
Time frame: Throughout the study period, until 36 months post-dose 3/4
Adverse events
Percentage of occurrence, types, duration and severity of adverse events and severe adverse events throughout study period
Time frame: Throughout the study period, until 36 months post-dose 3/4
Binding anti-N antibody response
Geometric mean levels and geometric mean fold rise of SARS-CoV2 N-specific binding antibody as determined by Enzyme-linked Immunosorbent Assay in Arm C participants receiving CoronaVac
Time frame: 1 month post-dose 1, and 1, 6, 18, and 36 months post-dose 3 (and 2 weeks after dose 4)
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