Trial design
We conducted a randomized, double-blind, controlled phase 2 trial to assess the safety and immunogenicity of the mosaic-type trimeric RBD vaccine, named NVSI-06-09, as a heterologous booster shot following primary vaccination of an inactivated vaccine BBIBP-CorV. The homologous boost of another dose of BBIBP-CorV was used as control in the study. The trial was reviewed and approved by the Abu Dhabi Health Research and Technology Ethics Committee of UAE, and conducted under the principles of the International Conference on Harmonization-Good Clinical Practice (ICH-GCP) and the Declaration of Helsinki (with amendments). This study also met the local legal and regulatory requirements of UAE. The sponsors of the study are China National Biotec Group Co., Ltd (CNBG) of Sinopharm, National Vaccine and Serum Institute (NVSI) of Sinopharm CNBG, Lanzhou Institute of Biological Products Co., Ltd (LIBP) of Sinopharm CNBG, and Beijing Institute of Biological Products Co., Ltd (BIBP) of Sinopharm CNBG. The study protocol is provided in the Supplementary Protocol. The trial is registered with ClinicalTrials.gov (NCT05293548), and the study is still ongoing.