Efficacy and Safety of a Recombinant Plant-Based Adjuvanted Covid-19 Vaccine

Karen J Hager, Gonzalo Pérez Marc, Philipe Gobeil, Ricardo S Diaz, Gretchen Heizer, Conrado Llapur, Alexander I Makarkov, Eduardo Vasconcellos, Stéphane Pillet, Fernando Riera, Pooja Saxena, Priscila Geller Wolff, Kapil Bhutada, Garry Wallace, Hessam Aazami, Christine E Jones, Fernando P Polack, Luciana Ferrara, Judith Atkins, Iohann BoulayJiwanjeet Dhaliwall, Nathalie Charland, Manon M J Couture, Julia Jiang-Wright, Nathalie Landry, Sophie Lapointe, Aurélien Lorin, Asif Mahmood, Lawrence H Moulton, Emily Pahmer, Julie Parent, Annie Séguin, Luan Tran, Thomas Breuer, Maria-Angeles Ceregido, Marguerite Koutsoukos, François Roman, Junya Namba, Marc-André D'Aoust, Sonia Trepanier, Yosuke Kimura, Brian J Ward, CoVLP Study Team

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35 Citations (Scopus)


BACKGROUND: Coronavirus-like particles (CoVLP) that are produced in plants and display the prefusion spike glycoprotein of the original strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are combined with an adjuvant (Adjuvant System 03 [AS03]) to form the candidate vaccine.

METHODS: In this phase 3, multinational, randomized, placebo-controlled trial conducted at 85 centers, we assigned adults (≥18 years of age) in a 1:1 ratio to receive two intramuscular injections of the CoVLP+AS03 vaccine or placebo 21 days apart. The primary objective of the trial was to determine the efficacy of the CoVLP+AS03 vaccine in preventing symptomatic coronavirus disease 2019 (Covid-19) beginning at least 7 days after the second injection, with the analysis performed after the detection of at least 160 cases.

RESULTS: A total of 24,141 volunteers participated in the trial; the median age of the participants was 29 years. Covid-19 was confirmed by polymerase-chain-reaction assay in 165 participants in the intention-to-treat population; all viral samples that could be sequenced contained variants of the original strain. Vaccine efficacy was 69.5% (95% confidence interval [CI], 56.7 to 78.8) against any symptomatic Covid-19 caused by five variants that were identified by sequencing. In a post hoc analysis, vaccine efficacy was 78.8% (95% CI, 55.8 to 90.8) against moderate-to-severe disease and 74.0% (95% CI, 62.1 to 82.5) among the participants who were seronegative at baseline. No severe cases of Covid-19 occurred in the vaccine group, in which the median viral load for breakthrough cases was lower than that in the placebo group by a factor of more than 100. Solicited adverse events were mostly mild or moderate and transient and were more frequent in the vaccine group than in the placebo group; local adverse events occurred in 92.3% and 45.5% of participants, respectively, and systemic adverse events in 87.3% and 65.0%. The incidence of unsolicited adverse events was similar in the two groups up to 21 days after each dose (22.7% and 20.4%) and from day 43 through day 201 (4.2% and 4.0%).

CONCLUSIONS: The CoVLP+AS03 vaccine was effective in preventing Covid-19 caused by a spectrum of variants, with efficacy ranging from 69.5% against symptomatic infection to 78.8% against moderate-to-severe disease. (Funded by Medicago; ClinicalTrials.gov number, NCT04636697.).

Original languageEnglish
Number of pages13
JournalThe New England Journal of Medicine
Early online date4 May 2022
Publication statusE-pub ahead of print - 4 May 2022


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