Top U.S. infectious diseases expert, Dr. Anthony Fauci responded to Britain's plans to delay giving the coronavirus vaccine booster shot in an attempt to ensure more people could be given the more limited protection conferred by a single dose. Fauci recommended that vaccines should be led by science administered in the U.S. "the way clinical trials have instructed us to do it." He also warned on Sunday the mutated strain of COVID-19 was in the U.S. and will spread.