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World’s first plant-based COVID-19 vaccine shares positive results

A Southampton-led UK study into the world's first plant-based COVID-19 vaccine has found it is 75% effective against the Delta variant.

The new vaccine from Medicago and GSK reported positive results against all variants seen in the trial. The Omicron variant was not circulating during the study.

Nearly 300 participants across 11 sites took part in the UK trial led by Southampton’s Dr Chrissie Jones. In total, around 24,000 adult volunteers were involved across six countries.

No related serious adverse events were reported and reactions after vaccination were generally mild to moderate.

Plant-based platform for new vaccines

The Phase 3 placebo-controlled study assessed Medicago’s vaccine candidate in combination with GSK’s pandemic adjuvant, a vaccine ingredient used to create a stronger immune response.

Dr Chrissie Jones, Associate Professor in Paediatric Infectious Diseases at University of Southampton, and Chief Investigator for the study said: “We are very grateful for the contributions of participants on the Medicago study, which have helped to identify another effective vaccine to help fight coronavirus.

“The fact the vaccine candidate from Medicago and GSK is shown to produce a robust immune response is exciting news as this plant-based platform can produce new vaccines. This could help support countries around the world which are yet to vaccinate their population, as it may be easier to manufacture and scale up, aiding low- middle-income countries.”

Developing Virus-Like Particles

Medicago has been developing its plant-based technology for the past 20 years. The technique produces Virus-Like Particles (VLP) for its protein vaccines.

VLPs are designed to mimic the native structure of viruses, allowing them to be easily recognised by the immune system. Because the VLPs lack core genetic material, they are non-infectious and unable to replicate.

VLP vaccines developed by other technologies have traditionally been used worldwide for more than 30 years.

Yosuke Kimura, Chief Scientific Officer at Medicago, said: “I am pleased to see our vaccine candidate moving forward and bringing to the world the first plant-based vaccine against COVID-19, diversifying the pool of vaccines available to help improve public health and protect more people.”

The vaccine candidate is not approved yet by any regulatory authorities. Full results of the Phase 3 study will be released in a peer-reviewed publication as soon as possible.

UK support for global vaccine

The 293 participants recruited in the UK were vaccinated between April and June 2021. The trial took place while the UK vaccine rollout was taking place, which impacted on the final number of volunteers. The first participant in Europe was recruited at the Swansea Bay University Local Health Board site.

Prof Andrew Ustianowski, National Clinical Lead for the UK NIHR COVID Vaccine Research Programme, said: “We are pleased to see this latest vaccine study findings, which have been supported by research teams and volunteers across the UK.

“The NIHR and our UK research community partners, along with the support of participants, continue to help to discover safe and effective vaccines to fight COVID-19. Positive study results such as this demonstrate that there is still a lot to learn and room for innovation within vaccine research.”


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