Dr Anthony Fauci says the government is working on several potential vaccines for COVID-19.
We have many candidates and hope to have many winners, he told the Senate Health, Education, Labour and Pension committee. In other words, it is many shots on goal.
Despite the rapid pace of work on vaccines, Fauci was offering no guarantees.
He says, The big unknown is efficacy.
Fauci heads the National Institute of Allergy and Infectious Diseases and is the government's leading expert on the pandemic. He says he hopes to have a vaccine in advanced trials by late fall or early winter.