Capacity of serum to neutralise SARS-CoV-2 spike protein-expressing pseudovirus will be assessed by a pseudovirus neutralisation assay.[Prior to initial vaccine dose; 20 days post initial vaccine dose; 20 days post vaccine booster dose (primary timepoint); 26 weeks post vaccine booster dose.];Detectable seroconversion of IgG against SARS-CoV-2 spike protein and receptor-binding domain will be assessed by enzyme-linked immunosorbent assay. [Prior to initial vaccine dose; 20 days post initial vaccine dose; 20 days post vaccine booster dose (primary timepoint); 26 weeks post vaccine booster dose.];SARS-CoV-2 spike protein-specific T cell response will be assessed by IFN-gamma ELISpot. [Prior to initial vaccine dose; 20 days post initial vaccine dose; 20 days post vaccine booster dose (primary timepoint); 26 weeks post vaccine booster dose.]

Capacity of serum to neutralise SARS-CoV-2 spike protein-expressing pseudovirus will be assessed by a pseudovirus neutralisation assay.[Prior to initial vaccine dose; 20 days post initial vaccine dose; 20 days post vaccine booster dose (primary timepoint); 26 weeks post vaccine booster dose.];Detectable seroconversion of IgG against SARS-CoV-2 spike protein and receptor-binding domain will be assessed by enzyme-linked immunosorbent assay. [Prior to initial vaccine dose; 20 days post initial vaccine dose; 20 days post vaccine booster dose (primary timepoint); 26 weeks post vaccine booster dose.];SARS-CoV-2 spike protein-specific T cell response will be assessed by IFN-gamma ELISpot. [Prior to initial vaccine dose; 20 days post initial vaccine dose; 20 days post vaccine booster dose (primary timepoint); 26 weeks post vaccine booster dose.]