Safety and efficacy of SCB-2019 COVID vaccine candidate as a ChAdOx1-S booster

The standard formulation containing 30 μg SCB-2019 with the toll-like receptor 9 (TLR-9) agonist CpG-1018 and alum showed the best booster response. This formulation demonstrated acceptable reactogenicity, comparable to that observed in the SPECTRA study. Moreover, it was safe and highly efficacious as a heterologous booster following primary vaccination.