The head of emergencies at the World Health Organization is hailing "good news" in results shown by two COVID-19 vaccine candidates in early trials, but warns "there's a long way to go."
"We now need to move into larger-scale real-world trials," Dr Michael Ryan told reporters at a news conference in Geneva.
"But it is good to see more data and more products moving into this very important phase of vaccine discovery."
Ryan's comments came as scientists at Oxford University, in a paper published in The Lancet, said their experimental vaccine had been shown to trigger a protective immune response in hundreds of people who got the shot.
Also in the medical journal, Chinese researchers published a study on their experimental vaccine, using a similar technique as the Oxford team, that reported an immune response. Ryan noted there are 23 COVID-19 candidate vaccines in clinical development, but until Monday only one had produced Phase 1 clinical data.