On Sept. 22, 2021, Clover Biopharmaceuticals, a global clinical-stage biotechnology company developing novel vaccines and biologic therapeutic candidates, and CEPI, the Coalition for Epidemic Preparedness Innovations, announced that 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. 

The SPECTRA clinical trial enrolled over 30,000 adult and elderly (≥18 years of age) participants at 31 sites in five countries (Philippines, Brazil, Colombia, South Africa, Belgium) across four continents, resulting in one of the most diverse COVID-19 vaccine clinical trials conducted to-date. SPECTRA was funded by CEPI as part of a up to $328 million investment to develop and enable equitable access to SCB-2019 (CpG 1018/Alum). 

SPECTRA is a 1:1 randomized, double-blinded, placebo-controlled Phase 2/3 trial to evaluate the efficacy, safety and immunogenicity of SCB-2019 (CpG 1018/Alum) compared to placebo. 30,128 adult and elderly subjects (≥18 years of age) were randomized and dosed with SCB-2019 (CpG 1018/Alum) or placebo administered in a two-dose regimen (21 days apart).

SPECTRA (Study Evaluating Protective-Efficacy and Safety of Clover’s Trimeric Recombinant Protein-based and Adjuvanted COVID-19 Vaccine) is a 1:1 randomized, placebo-controlled, double-blinded study to evaluate the efficacy, safety and immunogenicity of SCB-2019 (CpG 1018/Alum) compared to placebo in over 30,000 participants 18 years of age and older in 31 study sites in the Philippines, Brazil, Colombia, South Africa and Belgium. Participants received SCB-2019 (CpG 1018/Alum) administered in a two-dose regimen, 21 days apart, or placebo. Efficacy and safety result are reviewed by the independent Data and Safety Monitoring Board (DSMB), and all COVID-19 cases included in the efficacy analysis were adjudicated by an independent Endpoint Adjudication Committee (EAC). The SPECTRA study is sponsored by Clover and is funded by CEPI.

The primary endpoint for SPECTRA was prevention of PCR-confirmed symptomatic COVID-19 of any severity (mild, moderate or severe) with onset ≥14 days after the second dose in adult and elderly participants (≥18 years of age) without evidence of prior SARS-CoV-2 infection (seronegative) at baseline. The statistical success criterion was lower bound 95.72% CI >30%.

Predefined key secondary endpoints with available results included prevention of PCR-confirmed moderate-to-severe COVID-19 and severe COVID-19 with onset ≥14 days after the second dose in adult and elderly participants (≥18 years of age) without evidence of prior SARS-CoV-2 infection (seronegative) at baseline. The statistical success criterion was lower bound 97.86% CI >0%.