Top US epidemiologist Dr Anthony Fauci said that he is cautiously optimistic about Covid-19 vaccine.
Fauci said the vaccine for Covid-19 may be available by the end of the year.
Appearing before a House panel investigating the nation's response to the Covid pandemic, Fauci expressed 'cautious' optimism that a vaccine would be available, particularly by next year.
Phase 3 clinical trial of a vaccine discussed by Fauci began on Monday.
Federal health authorities under direction from the White House are carrying out a plan to manufacture 300 million doses of a vaccine on a compressed timeline.
Fauci is the nation’s top infectious disease official.
He informed that a quarter-million people have expressed interest in taking part in studies of experimental vaccines for the coronavirus.
Nearly 250,000 people have registered on a government website to take part in vaccine trials, he added.
However, not all patients who volunteer to take part in clinical trials are eligible to participate.
The trial for vaccine to be conducted at nearly 100 research sites and it is expected to enroll around 30,000 volunteers.
US has over 4.6 million cases of Covid-19, the highest in the world.
Over 155,000 people have died in America so far due to the infection.