The US government has ordered 300 million doses of a potential COVID-19 vaccine being developed by AstraZeneca and Oxford University and hopes first doses can be made available by October, the Department of Health and Human Services said on Thursday. "This contract with AstraZeneca is a major milestone in Operation Warp Speed’s work toward a safe, effective, widely available vaccine by 2021," HHS Secretary Alex Azar said in a statement AstraZeneca expects to be able to deliver a billion doses of a possible COVID-19 vaccine this year and next if tests are successful, adding on Thursday it should shortly get results of an early stage clinical trail.