It is "highly unlikely" a Covid-19 vaccine would be ready by election day, a senior administration official close to the coronavirus task force told CNN.
"Metaphysically possible. But highly unlikely," the official said.
The official added there is reason to be hopeful for a vaccine in the coming months as progress continues to be made.
"There will be lots to talk about, for sure," the official continued. "The trials are going very well."
A vaccine could come in early 2021, around inauguration day in January, said the official who also described that timeline as "optimistic."
More about vaccine timing: Last week, Dr. Anthony Fauci said he is cautiously optimistic that human trials of a coronavirus vaccine being developed by Moderna might show whether it’s both safe and effective by late fall or early winter.
Fauci — who as director of the National Institute of Allergy and Infectious Diseases helps lead federal vaccine development efforts — has repeatedly said he hoped the vaccine could start to be available by early next year, and then widely available in the spring and summer of next year if things go well.
President Trump on Thursday suggested a vaccine could be available by Election Day, saying he is “optimistic that it’ll be probably around that date.”