WASHINGTON, Aug. 5 (Reuters) - The United States government will pay Johnson & Johnson more than US$1 billion for 100 million doses of its potential coronavirus vaccine, as it stocks up on vaccine and drugs in an attempt to tame the pandemic.

The latest contract is priced at roughly US$10 per vaccine dose produced by J&J, or around US$14.50 per dose, including a previous US$456 million the US government promised to J&J for vaccine development in March.

That compares with the US$19.50 per dose that the US is paying for the vaccine being developed by Pfizer and German biotech BioNTech.

J&J is studying both one and two-dose regimens of its vaccine. Pfizer and BioNTech's candidate would require two doses per person treated. The drugmaker said on Wednesday it would deliver the vaccine to the Biomedical Advanced Research and Development Authority (BARDA) on a not-for-profit basis to be used after approval or emergency use authorization by the US Food and Drug Administration (FDA).

The US government may also purchase an additional 200 million doses under a subsequent agreement. J&J did not disclose that deal's value.

With the latest deal, President Donald Trump's administration has spent US$9.4 billion on vaccine agreements, with five companies agreeing to provide at least 700 million doses, according to an AFP tally.

These deals, under Operation Warp Speed, foresee launching production in parallel with clinical trials, with the government taking the financial risk away from the private sector.

The US has also spent billions on building manufacturing sites, on companies that make syringes and vials, and on the development of treatments.

Washington has bought up almost all stock of the antiviral drug remdesivir that will be produced until September. The medicine is the first treatment with proven benefit against COVID-19.

Other drugmakers who have signed deals include Sanofi and Regeneron.

This is J&J's first deal to supply its investigational vaccine to a country. Talks are underway with the European Union, but no deal has yet been reached.

J&J's investigational vaccine is currently being tested on healthy volunteers in the United States and Belgium in an early-stage study.

There are currently no approved vaccines for COVID-19. More than 20 are in clinical trials.

Shares of J&J were up around 1 per cent in early trading on the New York Stock Exchange.