“There’s no guarantee that the vaccine is actually going to be effective,” Dr. Anthony Fauci tells Sen. Burr, on COVID-19 vaccine development efforts. https://t.co/4D1xwIZzVi

"I am cautiously optimistic that we will with one of the candidates get an efficacy signal." pic.twitter.com/YRNDAOQasJ

— ABC News (@ABC) May 12, 2020