1. Two doses of the CoVLP+AS03 vaccine reduced the risk of contracting coronavirus disease 2019 (COVID-19) and infection severity compared to placebo.
2. While adverse events were more common in the vaccine compared to the placebo group, most were transient and mild or moderate in severity.
Evidence Rating Level: 1 (Excellent)
Study Rundown: The COVID-19 pandemic has resulted in the development and implementation of multiple mRNA-based vaccines. Though, there are associated concerns related to risk of adverse events and need for cold storage. This phase three randomized control trial evaluated the efficacy and safety of the novel CoVLP+AS03 COVID-19 vaccine as compared to a placebo control vaccine. Each group received two doses 21 days apart. It is the first plant-based vaccine approved for human use. The vaccine consists of plant-derived SARS-CoV-2 virus-like particles (CoVLP) and adjuvant system 03 (AS03). Patients were followed for a minimum of two months after vaccination. Those in the CoVLP+AS03 group demonstrated a significantly reduced risk of contracting COVID-19 as compared to placebo controls. Additionally, vaccination was associated with reduced disease severity and viral load at diagnosis in participants who did contract COVID-19. The study group reported significantly more adverse events than the placebo group, most of which were mild to moderate in severity. Vaccine efficacy and safety among individuals over 65 years old were not reported due to limited sample size. This is a major limitation given the higher risk of COVID-19 morbidity and mortality in this population.
Relevant Reading: Whole Inactivated Virus and Protein-Based COVID-19 Vaccines
In-Depth [randomized controlled trial]: In the present study, participants were randomly assigned to receive CoVLP+A03 (n=12,074) or placebo (n=12,067) vaccinations, of which 10,554 CoVLP+A03 and 9,536 placebo participants received two doses. Safety data was only available for a subset of the cohort. Participants were monitored for known adverse events associated with previously approved COVID-19 vaccines for seven days after injection. Further adverse events were monitored for 21 days. In total, 165 COVID-19 cases occurred of which 40 occurred in the vaccinated group. The overall vaccine efficacy was 69.5% (95% confidence interval [CI], 56.7 to 78.8) for preventing COVID-19 infection. The vaccine efficacy for preventing moderate-to-severe disease was 78.8% (95% CI, 55.8 to 90.8). The viral load of COVID-19 infected individuals in the study group was over 100-fold lower than that in the placebo group. Though, there was a higher incidence of solicited adverse events in the vaccinated group than in the placebo group (92.3% and 45.5% respectively for local events, and 87.3% and 65.0% respectively for systemic events). The incidence of unsolicited adverse events was not significantly different between groups. CoVLP+AS03 is the first plant-based vaccination modality to be approved for human use and may serve as a feasible alternative or booster shot to currently available options.
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