In September 2023 Gritstone bio announced that is has been awarded a contract by BARDA to conduct a Phase IIb comparative study that will evaluate the company’s self-amplifying mRNA (samRNA) vaccine candidate, targeting COVID-19. The agreement is valued at up to $433 million and is part of the US HHS initiative ‘Project NextGen’. This aims to “leverage public-private partnerships” in pursuit of new vaccines and therapeutics for COVID-19.  

The study 

The contract will support Gritstone as it conducts a 10,000 participant, randomised Phase IIb double-blinded study. The study will compare the efficacy, safety, and immunogenicity of the company’s next-generation COVID-19 vaccine candidate with an approved vaccine. Gritstone reports that “preparations for the study are underway”, with the execution being “fully funded by BARDA”. It will take place in the US, in collaboration with the COVID-19 Prevention Network (CoVPN), which is a NIAID-supported network of trial sites based at Fred Hutchinson Cancer Centre.  


Gritstone explains that self-amplifying mRNA (samRNA) is “rapidly emerging” as a “well-tolerated, scalable, and widely applicable platform technology”. It can be used in multiple vaccines if the sequence of the antigen that is encoded in the vector RNA is changed. Like “traditional mRNA vaccines”, these vaccines use the host cell’s translation system to “convert mRNA” to protein target antigens, stimulating immunity. However, in contrast to traditional mRNA, samRNA “creates multiple copies of the antigen RNA once in the cell”, which is believed to be a possible factor in extending the “duration and magnitude of antigen expression”.  

The CORAL programme 

Gritstone’s CORAL programme applies the team’s infectious disease approach to the prevention of COVID-19, aiming to drive both B cell and T cell immunity using self-amplifying mRNA (samRNA) and novel immunogens containing Spike and additional viral targets. So far, the programme has involved three Phase I trials. It is supported by BARDA, NIAID, CEPI, and the Gates Foundation.  

Dr Andrew Allen, Co-founder, President, and CEO of Gritstone bio is “honoured” to receive the award, which provides “strong validation” of the innovative vaccine platform in infectious diseases.  

“Not only does this contract supply the necessary resources to advance the development of CORAL, but it also signifies the trust and confidence the US government has placed in our novel vaccine approach.” 

Dr Allen recognised the “great utility” of first-generation COVID-19 vaccines during “the height of the pandemic”. However, they are “limited in breadth and durability of clinical protection”. Thus, CORAL was designed to “address these limitations”. In “multiple Phase I studies” the vaccine has demonstrated “induction of potent immune responses with potential to drive broad and durable clinical protection”.  

“We are excited about this opportunity to work alongside BARDA and look forward to initiating the Phase IIb study in the first quarter of 2024…Gritstone now sits at the precipice of unlocking the full potential of our novel vaccine platforms in both oncology and infectious diseases.”  

We were lucky to speak to Dr Allen about his team’s efforts against cancer at the Congress in Washington in April; you can check out our interview here. For more from Gritstone bio at the World Vaccine Congress in Barcelona, get your tickets here. Don’t forget to subscribe to our newsletters here!