The U.S.’ top medical expert on the coronavirus pandemic, Anthony Fauci, said on Sunday that it would be clear whether a COVID-19 vaccine was safe and effective by late November or early December. 

In an interview with the BBC, Fauci, the head of the National Institute of Allergy and Infectious Diseases, then added, however, that there won’t be enough doses to vaccinate the general public at that time.

The public health expert said there is a set prioritization, with the first doses going to health care workers and then those at an increased risk of getting COVID-19.

Fauci reportedly predicted that it will be very difficult until the second or third quarter of next year for the vaccine to become widely available nationally.