A clinical trial evaluating a vaccine designed to protect against the new coronavirus will begin on Monday, according to a US government official.
Testing will begin with 45 young, healthy volunteers with different doses of shots co-developed by NIH and Moderna Inc.
The first participants will receive the experimental vaccine on Monday,
Public health officials say it will take a year to 18 months to fully validate any potential vaccine.
There's no chance participants could get infected from the shots, because they don't contain the virus itself.
The goal is purely to check that the vaccines show no worrisome side effects, setting the stage for larger tests.
Dozens of research groups around the world are racing to create a vaccine as COVID-19 cases continue to grow. Importantly, they're pursuing different types of vaccines - some researchers are even aiming for temporary vaccines, such as shots that might guard people's health a month or two at a time while longer-lasting protection is developed.
The worldwide outbreak has made more than 156,000 people ill and left more than 5,800 dead.
The vast majority of people recover. According to the World Health Organisation, people with mild illness recover in about two weeks, while those with more severe illness may take three weeks to six weeks to recover.
The National Institutes of Health is funding the trial, which is taking place at the Kaiser Permanente Washington Health Research Institute in Seattle, the official said.