The second phase of human trials for a universal flu vaccine has begun in the U.S., the National Institutes of Health announced Friday, as scientists continue to search for an all-encompassing solution to protecting against the unpredictable and constantly mutating virus. The clinical trial, which will take place at four sites around the U.S., will enroll 120 healthy volunteers to either be injected with the experimental vaccine, called M-001, or a placebo. Six previous clinical trials with a total of 698 participants in Israel and Europe established that M-001 was safe, well-tolerated and produced an immune response to a broad...