Democratic presidential nominee Joe Biden on Thursday night said that once scientists say there is a safe and effective coronavirus vaccine, he will "take it and encourage people to take it."

Biden fielded multiple questions about the coronavirus pandemic during an ABC News town hall in Philadelphia. He derided President Trump for saying "this crazy stuff he's walking away from now – inject bleach in your arm and that's going to work. I'm not being facetious though — he actually said those things."

Biden said he regularly meets with scientists working on the vaccine, and he praised their research. Regarding a vaccine mandate, Biden said it "depends on the state of the nature of the vaccine when it comes out and how it's being distributed. But I would think that we should be talking about, depending on the continuation of the spread of the virus, we should be thinking about making it mandatory."

Moderator George Stephanopoulos asked Biden why he didn't tell people to wear masks during the early days of the pandemic in January and February, and Biden responded that he urged people to don face coverings in March once the practice was recommended by scientists like Dr. Anthony Fauci, the nation's top infectious disease expert. "What we should be doing now, there should be a national standard," Biden said. "Remember what the president said to the governors — well, they're on their own, it's not my responsibility, the governors can do what they need to do, not my responsibility. It is a presidential responsibility to lead. And he didn't do that."