A billion doses of a possible COVID-19 vaccine, to be available this year and next.

That's AstraZeneca's plan if tests are successful.

The pharmaceutical company on Thursday (May 21) added that it should shortly get results of an early stage clinical trial.

The British drugmaker has already signed the first agreements to supply at least 400 million doses of the vaccine, which it is developing with Oxford University.

It's said that if results from the early stage tests are positive, they will lead to late stage trials in several countries.

Only a handful of vaccines in development have advanced to human trials.

That stage is seen as an indicator of safety and efficacy.

But it's the point when many new drugs fail.

Governments, drugmakers and researchers around the world are working on around 100 programs.

Though experts warn it could take 12 to 18 months to develop a vaccine.

AstraZeneca also said it had received more than $1 billion from the U.S. Biomedical Advanced Research and Development Authority towards the potential treatment.

Other drugmakers including Pfizer, Johnson & Johnson and Sanofi are also in various stages of vaccine development.

AstraZeneca said it was engaging with international bodies over the fair allocation and distribution of any new product around the world.