Moderna and the US Biomedical Advanced Research and Development Authority (BARDA) have updated their contract for an additional funding commitment of up to $472m.

The funding will support the late-stage clinical development of the company’s Covid-19 vaccine candidate, mRNA-1273, including the expanded Phase III clinical trial.

Previously, BARDA agreed to provide up to $483m for the scale-up of the vaccine and clinical development, which was supposed to involve a smaller number of participants in the Phase III study.

After discussions with the US Food and Drug Administration (FDA) and Operation Warp Speed , Moderna has decided to expand the Phase III trial and involve nearly 30,000 participants in the US.

The amended contract brings the total value of the award to around $955m.

Moderna CEO Stéphane Bancel said: “Encouraged by the Phase I data, we believe that our mRNA vaccine may aid in addressing the Covid-19 pandemic and preventing future outbreaks.”

Set to begin today, the Phase III trial, named Cove , will be in alliance with the US National Institutes of Health (NIH)’s National Institute of Allergy and Infectious Diseases (NIAID).

The randomised, placebo-controlled trial will assess 100µg dose level in the US. The primary endpoint will be the prevention of symptomatic Covid-19.

Key secondary endpoints include the prevention of severe Covid-19 disease and infection by SARS-CoV-2.

Moderna added that the company is on track to deliver around 500 million Covid-19 vaccine doses per year and potentially up to one billion doses per year, beginning next year, at its US manufacturing site and as part of the collaboration with Lonza .

The company also partnered with Catalent for large-scale, commercial fill-finish manufacturing of the Covid-19 vaccine candidate at the partner’s biologics facility in Indiana, US.

In a public equity offering in May, the company received initial funding of $1.3bn from investors to start manufacturing mRNA-1273 supply at-risk.