Clinical Trial Info

A Controlled Phase 2/3 Study of Adjuvanted Recombinant SARS-CoV-2 Trimeric S-protein Vaccine (SCB-2019) for the Prevention of COVID-19 (SCB-2019)

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This Phase 2/3 study will assess the efficacy against COVID-19 and SARS-CoV-2 infection, immunogenicity, reactogenicity, and safety of CpG 1018/Alum-adjuvanted SCB-2019 vaccine in 30,000 participants adults 18 years and older, across 4 continents.


Clover and CEPI announced that Clover's COVID-19 vaccine candidate successfully achieved the primary endpoint as well as demonstrating SCB-2019 (CpG 1018/Alum) demonstrated efficacy against the globally dominant Delta strain and other concerning variants.

Clover's adjuvanted protein-based COVID-19 vaccine candidate, SCB-2019 (CpG 1018/Alum) achieved the primary efficacy endpoint and secondary efficacy endpoints in SPECTRA, a global pivotal Phase 2/3 clinical trial. Vaccine efficacy was successfully demonstrated in an environment where 100% of SARS-CoV-2 strains observed in the efficacy analysis were variants. SCB-2019 (CpG 1018/Alum) demonstrated 79% overall efficacy against COVID-19 of any severity caused by the globally dominant Delta variant, which currently comprises over 90% of all cases worldwide. Efficacy was 92% against the Gamma variant and 59% against the Mu variant, and collectively these three strains (Delta, Gamma and Mu) comprised 73% of all strains identified in the study. Overall efficacy was 67% against COVID-19 of any severity caused by any strain in the study, successfully meeting the primary endpoint of the trial.Clover's vaccine candidate is one of the first to demonstrate significant efficacy against Delta in a double-blind, randomized clinical trial.