Pfizer's announcement Monday of a potentially effective coronavirus vaccine triggered a wave of hope and optimism, renewing some expectations that life in the U.S. could return to normal sometime in 2021. Normal, however, is a ways away. Not every aspect of society will bounce back immediately, with rollouts of the vaccines starting with essential workers and plans dictating numerous phases of reopening, experts said. And a vaccine, even one with promising early results, cannot do anything to stop a grueling winter, with outbreaks growing rapidly across the country and record hospitalization rates threatening to overwhelm health care resources.