Plant-based coronavirus vaccine shows ‘positive efficacy and safety results,’ developers say

Pharmaceutical company GlaxoSmithKline (GSK) on Tuesday announced positive results from a phase three trial of its plant-based coronavirus vaccine, the first inoculant of its kind to reach a stage to seek emergency approval.

The vaccine has an overall efficacy rate of 71 percent against all variants of the Sars-CoV-2 virus with the exception of omicron and is about 75 percent effective against the disease caused by the virus, COVID-19.

GSK partnered with Canadian biopharmaceutical company Medicago to develop the vaccine against the novel coronavirus. Medicago, which developed the vaccine with a GSK adjuvant, or additional substance to improve the vaccine, will immediately submit trial data and seek approval from Health Canada, the regulatory agency in the country. Filing processes for emergency approval have already been initiated in the U.S. and the U.K., GSK said in a press release.

“This is an incredible moment for Medicago and for novel vaccine platforms,” said Takashi Nagao, the president of Medicago, in a statement. “The results of our clinical trials show the power of plant-based vaccine manufacturing technology. If approved, we will be contributing to the world’s fight against the COVID-19 pandemic with the world’s first plant-based vaccine for use in humans.”

The vaccine trial was conducted among 24,000 adults spread across six countries. Patients in the trial reported no serious or adverse symptoms.

The results show the two-dose vaccine is especially effective compared to other approved vaccines because it was trialed in “an environment dominated by SARS-CoV-2 variants,” such as gamma and the dominant delta.

Medicago and GSK have both previously used virus-like particles, a 30-year-old technology, to produce protein vaccines. Living plants are used as bioreactors to produce non-infectious protein particles that mimic the native structure of viruses and thus bolsters the immune system response to an invading virus. In its vaccines, Medicago says it uses the plant species Nicotiana benthamiana, a close relative of the tobacco plant.

Medicago is developing a number of plant-based vaccines to combat the seasonal flu and the norovirus, among others. And GSK has a common vaccine made from virus-like particles that offers inoculation against hepatitis b.

Plant-based vaccines are typically cheaper to make and safer for patients. GSK said the new vaccine would not need to be stored in unusually cold temperatures like the Moderna and Pfizer vaccines, making it easier for distribution, too.

“The global COVID-19 pandemic is continuing to show new facets with the current dominance of the Delta variant, upcoming Omicron, and other variants likely to follow,” said Thomas Breuer, the chief global health officer at GSK, in a statement. “The combination of GSK’s established pandemic adjuvant with Medicago’s plant-based vaccine technology has significant potential to be an effective, refrigerator-stable option to help protect people against SARS-CoV-2.”