Recombinant plant-based Covid-19 vaccine promising for infection control: NEJM

Canada: In a new study conducted by Karen J. Hager and team, it was shown that the Coronavirus-like particles (CoVLP) + Adjuvant System 03 (AS03) vaccination prevented Covid-19 caused by a wide range of variations, with effectiveness ranging from 69.5% against symptomatic infection to 78.8% against moderate-to-severe illness. The findings of this study were published in The New England Journal of Medicine.

CoVLP generated in plants and displaying the prefusion spike glycoprotein of the primary strain of SARS-CoV-2 are mixed with an adjuvant (AS03) to construct the candidate vaccine. The authors of this study provide preliminary findings from a pivotal phase 3 trial of the CoVLP+AS03 vaccine to assess its effectiveness and safety.

Researchers allocated people (≥18 years of age) in a 1:1 ratio to receive two intramuscular injections of the CoVLP+AS03 vaccination or placebo 21 days apart in this phase 3 randomized, international, placebo-controlled study conducted at 85 locations. The primary goal of the experiment was to establish the effectiveness of the CoVLP+AS03 vaccine in averting symptomatic coronavirus disease 2019 (Covid-19), starting at least 7 days after the second injection and continuing until at least 160 cases were detected.

The key findings of this study were as follows:

1. The experiment drew a total of 24,141 volunteers, with a median age of 29 years.

2. Covid-19 was verified in 165 people in the intention-to-treat group using a polymerase-chain-reaction test; all viral specimens that could be sequenced had variations of the original strain.

3. Vaccine effectiveness was 69.5% against any symptomatic Covid-19 induced by five sequence-identified variations.

4. In a post-hoc analysis, vaccination effectiveness against moderate-to-severe illness was 78.8% and 74.0% among those who were seronegative at baseline.

5. There were no severe instances of Covid-19 in the vaccination group, where the median viral load for breakthrough cases was more than 100 times lower than in the placebo group.

6. The reported adverse events were mostly mild or moderate and transient, and they were more common in the vaccine group than in the placebo group; local adverse events were reported in 92.3% and 45.5% of participants, respectively, and systemic adverse events occurred in 87.3% and 65.0%.

7. The incidence of unintentional adverse events was comparable in both groups up to 21 days after each dosage (22.7% and 20.4%, respectively) and from day 43 to day 201. (4.2% and 4.0%).

In conclusion, CoVLP+AS03 is the first plant-based vaccination authorized for human use and one of only a few plant-derived biopharmaceutical products. The possible impact of this plant-based technology in the present epidemic will be heavily determined by the pandemic's development. The availability and continued development of this platform, on the other hand, might have significant ramifications for pandemic preparedness.

Reference:

Hager, K. J., Pérez Marc, G., Gobeil, P., Diaz, R. S., Heizer, G., Llapur, C., Makarkov, A. I., Vasconcellos, E., Pillet, S., Riera, F., Saxena, P., Geller Wolff, P., Bhutada, K., Wallace, CoVLP Study Team (2022). Efficacy and Safety of a Recombinant Plant-Based Adjuvanted Covid-19 Vaccine. The New England journal of medicine, Advance online publication. https://doi.org/10.1056/NEJMoa2201300