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Vaccine description
Target SARS-CoV-2
Vaccine type Virus-like particles
Clinical data
Routes of

CoVLP is a COVID-19 vaccine candidate developed by Medicago and GlaxoSmithKline (GSK). It is a coronavirus virus-like particle vaccine grown in the Australian weed, Nicotiana benthamiana . [1] [2] [3]


The Medicago method to manufacture CoVLP is a "molecular farming" technology regarded as rapid, low-cost, and safe. [1] [4] It has been proposed specifically for production of COVID-19 vaccines. [5] [6]

As of January 2021, the Medicago CoVLP vaccine candidate was in a Phase II-III clinical trial in Canada and the United States, involving 30,918 participants. [7]


CoVLP is an example of a virus-like particle vaccine, consisting of a molecular complex which closely resembles a virus, but is non-infectious because its contains no viral genetic material. [1] It uses recombinant spike proteins derived from SARS-CoV-2. [8] [9]


N. benthamiana plant used by Medicago as a "minifactory" for rapid production of coVLP Nicoatiana benthamiana plant.jpg
N. benthamiana plant used by Medicago as a "minifactory" for rapid production of coVLP
Nicotiana benthamiana, leaf Nicotiana benthamiana leaf.jpg
Nicotiana benthamiana, leaf

The virus-like particles are produced by creating a bacterium engineered with genes of the virus, then introducing the bacteria into Nicotiana benthamiana plants. [1] The plants take up the bacteria virus-derived generic material, producing in its leaves the virus-like particles, which are then harvested and extracted. [3] [10]

In use since the 1990s, the method of using a plant like N. benthamiana has been called "molecular farming" or a "plant-based factory", having vaccine manufacturing advantages of rapid, low-cost production of proteins, large scalability for production, and safety of using plants for pharmaceutical production. [1] [4] It has been proposed specifically for production of COVID-19 vaccines. [5] [6]


Medicago is developing the COVID-19 vaccine candidate, CoVLP, in collaboration with the governments of Canada and Quebec, and by using an adjuvant manufactured by GlaxoSmithKline (GSK). [8] The GSK adjuvant is intended to enhance the immune response to CoVLP, reducing the amount of antigen required per dose, thereby facilitating mass production of vaccine doses. [11] [12]

Clinical trials

Phase I

Beginning in August 2020, CoVLP was in a Phase I clinical trial at two locations in Quebec to evaluate its safety and immune response. [13] Adults (18–55 years, n = 180) were randomized at two sites in Quebec, Canada, to receive two intramuscular doses of CoVLP (3.75 μg, 7.5 μg, and 15 μg) 21 d apart, alone or adjuvanted with AS03 or CpG1018. All formulations were well tolerated, and adverse events after vaccination were generally mild to moderate, transient and highest in the adjuvanted groups. There was no CoVLP dose effect on serum NAbs, but titers increased significantly with both adjuvants. After the second dose, NAbs in the CoVLP + AS03 groups were more than tenfold higher than titers in Coronavirus 2019 convalescent sera. Both spike protein-specific interferon-γ and interleukin-4 cellular responses were also induced. This pre-specified interim analysis supports further evaluation of the CoVLP vaccine candidate. [14]

Phase II

In November 2020, Medicago-GSK started a Phase II clinical trial for CoVLP with 588 participants. Researchers reported day 42 interim safety 17 and immunogenicity data from a Phase II, randomized, placebo-controlled trial in Adults aged 18+ immunized with a virus-like particle vaccine candidate produced in plants displaying 19 SARS-CoV-2 spike glycoprotein (CoVLP) adjuvanted with AS03 (NCT04636697). This report focuses on presenting safety, tolerability and immunogenicity, as measured by 21 neutralizing antibody (NAb) and cell mediated immunity (IFN-γ and IL-4 ELISpot) responses, 22 in Adults aged 18-64 (Adults) and Older Adults aged 65+ (Older Adults). The Phase II trial has a primary completion date of December 2021 and the estimated completion date of April 2022. [7] After a successful Phase II, the scientists moved into a Phase III trial.

Phase III

In April 2021, Medicago-GSK started a Phase III clinical trial for CoVLP, enrolling 30,918 participants in North America, Latin America, and Europe. [7] [15] [9] The Phase 3 portion is an event-driven, randomized, observer-blinded, crossover placebo-controlled design that will evaluate the efficacy and safety of the CoVLP formulation, compared to placebo.

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