- "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."
There are at least six potential vaccines in phase three human trials, including the ones from drug companies Pfizer and Moderna, Ryan said. There are more than 150 under development worldwide, he added.
Up until now, all the trials have been focused on safety and ensuring the vaccines generate an immune response in a small number of people, he said. "They are sort of gates that the vaccine has to go through. This is not a gate. It is a race for the vaccine now to demonstrate that it can protect large numbers of people."
While there is hope scientists will find a safe and effective vaccine, there is never a guarantee, WHO Director-General Tedros Adhanom Ghebreyesus said.
"We cannot say we have vaccines. We may or may not," he said.
The comments come after President Donald Trump said the U.S. may have a vaccine to prevent Covid-19 "far in advance" of the end of the year.
Earlier in the day, Trump said it's possible the United States could have a safe and effective vaccine for the coronavirus before the upcoming U.S. presidential election on Nov. 3.
"Oh I think, I think in some cases, it's possible before," Trump, who is seeking reelection, told conservative TV personality Geraldo Rivera "But right around that time. We have great companies, great, these are the greatest companies in the world.
Public health officials have repeatedly said a vaccine could be ready at the end of the year or early 2021, though there is no guarantee.
Scientists say questions remain about how the human body responds once it's been infected with the virus. The answers, they say, may have important implications for vaccine development, including how quickly it can be deployed to the public.
Additionally, officials need to make sure states have the vials, needles and syringes needed to administer the vaccine, or they could risk running out of it.
Dr. Anthony Fauci, the nation's leading infectious disease expert, has said a vaccine likely won't be "widely available" to the American public until "several months" into 2021.