Testing of an experimental COVID-19 vaccine has begun in volunteers in Britain, the latest in a cluster to begin early-stage studies.

University of Oxford researchers gave injections to volunteers Thursday in a study that eventually aims to enroll hundreds.

Scientists around the world are testing different types of potential vaccines against the new coronavirus, with no way to know which will work.

The Oxford candidate and one in China are made using a different, harmless virus.

Two U.S. companies are testing vaccines made from copies of a piece of the virus's genetic code.