Plant-based Covid shot shows ‘positive’ results

Pharmaceutical companies Medicago and GlaxoSmithKline have announced ‘‘positive efficacy and safety results’’ from a global trial using what they say is the world’s first plant-based coronavirus vaccine.

Studying 24,000 adults across six countries, the trial found that the overall efficacy rate of the vaccine candidate was 71 per cent, rising to 75.3 per cent against ‘‘Covid-19 of any severity for the globally dominant Delta variant’’. However, the trial did not include the newly identified Omicron variant.

The global, placebo-controlled efficacy study used Canada-based Medicago’s plant-based vaccine in combination with British drugmaker GSK’s pandemic adjuvant, an ingredient that works to boost the immune response and efficacy of others’ vaccines.

The companies said they hoped the vaccine would diversify the current pool of shots available, and said the trial had shown ‘‘no related serious adverse events’’.

The vaccine candidate has yet to be approved by any regulatory authority. However, Medicago said it had initiated the regulatory filing process in the United States and Britain.

The World Health Organisation has called plant-based vaccines, made by producing antigens in genetically modified plants that can then be extracted and purified by conventional methods, a ‘‘new and exciting possibility’’.

‘‘Plant-derived vaccines have several advantages,’’ the WHO said, including being ‘‘produced cheaply in very high amounts’’ using carrier plants such as potatoes and corn.

It said the antigens created were ‘‘stable and can be stored for long periods of time’’.