Former Vice President Joe Biden on Thursday called for a nationwide mask mandate to help fight the spread of the coronavirus pandemic. “Every American should be wearing a mask when they’re outside for the next three months at a minimum,” Biden told reporters in Wilmington, Del. The presumptive Democratic presidential nominee spoke after sitting down for a briefing on the coronavirus with public health experts. He was joined at the briefing by his newly named running mate, Sen. Kamala Harris of California.