Diversifying the Global COVID-19 Vaccine Portfolio

Novel COVID-19 vaccines in the pipeline include CoVLP+AS03 and ZF2001. To develop CoVLP+AS03, researchers expressed the SARS-CoV-2 S protein in plant cells, which produced coronavirus-like particles that were combined with the adjuvant AS03. In an international trial to characterize CoVLP+AS03's preventive efficacy, >24,000 participants (median age, 29; 14.8% SARS-CoV-2 seropositive, 9.8% with comorbidities) were randomized to receive 2 doses of vaccine or placebo 21 days apart. Among 165 COVID-19 cases, 40 were in the vaccine group and 125 in the placebo group for a vaccine efficacy of 69.5%. Of 3 severe cases, all were in the placebo group. At diagnosis, SARS-CoV-2 viral load in the upper airways was 100-fold lower in the vaccine group than the placebo group. Solicited local and systemic adverse events were more common in the vaccine group, especially after the second dose. Frequency of serious adverse events was similar between groups (0.2% [vaccine] and 0.1% [placebo]).

For ZF2001, investigators expressed the dimeric SARS-CoV-2 receptor-binding domain in Chinese hamster ovary cells and adjuvanted it with aluminum hydroxide. To determine the vaccine's efficacy at preventing COVID-19, investigators randomized almost 29,000 participants (median age, 35; <0.1% with previous SARS-CoV-2 infection, 13.2% with comorbidities) to receive 3 doses of ZF2001 or placebo 30 days apart; they then assessed RT-PCR–confirmed COVID-19. There were 158 COVID-19 cases (vaccine) and 580 cases (placebo) for an overall efficacy of 75.7%. Vaccine efficacy was 87.6% against severe disease (6 and 43 severe COVID-19 cases in the vaccine and placebo groups, respectively), and 86.5% against COVID-19 related death (2 and 12 deaths in the vaccine and placebo groups). Frequencies of solicited and unsolicited adverse events were comparable between groups. Serious adverse events occurred in 1.4% of ZF2001 recipients and 1.8% of placebo recipients.