KEY POINTS
  • "Phase three doesn't mean nearly there," Mike Ryan, executive director of the WHO's health emergencies program, said.
  • While there is hope scientists will find a safe and effective vaccine, there is never a guarantee, WHO Director-General Tedros Adhanom Ghebreyesus said.

Potential coronavirus vaccines entering late-stage human trials don't necessarily mean they are almost ready to be deployed widely to the general public, the World Health Organization said Thursday. 

"Phase three doesn't mean nearly there," Mike Ryan, executive director of the WHO's health emergencies program, said during a virtual panel discussion with "NBC Nightly News" Anchor Lester Holt hosted by the Aspen Security Forum. "Phase three means this is the first time this vaccine has been put into the general population into otherwise healthy individuals to see if the vaccine will protect them against natural infection."