The US government has bolstered its response to a potential Ebola outbreak by announcing plans to buy up more than a million doses of various treatments against the fatal virus.

The Biomedical Advanced Research and Development Authority (BARDA), which is part of the Office of the Assistant Secretary for Preparedness and Response (ASPR) within the US Department of Health and Human Services, is to add four products to its stockpile.

These are a single-dose vaccine from Merck Sharp & Dohme, a two-dose one from Janssen Vaccines and therapeutic drugs from Mapp Biopharmaceutical (ZMapp) and Regeneron Pharmaceuticals (REGN3470-3471-3479).

The companies will be provided with so-called Project BioShield funding by BARDA to help with late-stage development and submission for regulatory approval with the US Food and Drug Administration.

Merck will receive $39.2 million, Janssen $44.7 million, Mapp $45.9 million and Regeneron $40.4 million. Part of the money will also be used to purchase the products themselves: BARDA can buy up to 1.13 million regimens of the drugs for a potential public health emergency.

Project BioShield is designed to protect Americans from bioterrorism, as well as naturally-occurring outbreaks, and this is the first time that Ebola – which US authorities believe could be a threat on both counts - has been included in funding.

“This marks a pivotal moment in US and global preparedness for future public health emergencies from viral haemorrhagic fevers like Ebola,” said BARDA Director Rick Bright. “We reached this point at unprecedented speed, and that’s a direct result of innovative approaches to product development and to partnering across the US government, other nations and private industry.”

Ebola outbreaks usually occur in African countries: in the most recent, from 2014-16, more than 28,600 cases of Ebola virus infection were either suspected, probable or confirmed and more than 11,000 people died, according to the World Health Organisation.