WILMINGTON, Del. — Joe Biden on Wednesday expressed reservations about whether a coronavirus vaccine approved by the Trump administration would be safe, raising doubts about the president’s ability to put the health of Americans before politics. Biden said Americans should trust a coronavirus vaccine developed under the Trump administration only if the president gives “honest answers” to questions about its safety, effectiveness and equitable distribution. “I trust vaccines. I trust scientists. But I don’t trust Donald Trump,” Biden said. “And at this point, the American people can’t, either.”