Americans braced for what the nation's top doctor warned Sunday would be “the hardest and saddest week” of their lives while Britain assumed the unwelcome mantle of deadliest coronavirus hot spot in Europe after a record 24-hour jump in deaths that surpassed even hard-hit Italy's. Britain's own prime minister, Boris Johnson, was hospitalized, 10 days after testing positive for COVID-19 in what his office described as a “precautionary step.” Amid the dire news, there were also glimmers of hope some hard-hit areas — the number of people dying appeared to be slowing in New York City, Spain and Italy.