The head of Pfizer says there is a "good chance" the company will know if its COVID-19 vaccine works by the end of October.
Pfizer CEO Albert Bourla is optimistic, but warns it's still a longshot if Americans could actually get the vaccine before 2021.
The company is currently trying to enroll 44,000 people in its phase three vaccine trial, up from its original 30,000 pool.
Pfizer is one of three companies currently in the late-stages of testing for a vaccine.
The other two are Moderna and AstraZeneca, the latter of which announced Saturday it would resume its trial after temporarily pausing it for safety reasons.