The U.S. is likely soon to have a fourth vaccine approved for the fight against COVID-19. Novavax just released the results of its Phase 3 clinical trial: Its two-dose vaccine demonstrates 90 percent overall efficacy and 100 percent protection against both moderate and severe COVID-19 disease. The doses are injected three weeks apart. The company reports that 77 cases of COVID-19 were observed in its clinical trial involving nearly 30,000 participants. Of those cases, 63 occurred in the placebo group and 14 in the vaccine group. "All cases observed in the vaccine group were mild as defined by the trial...