Moderna said Monday that its Covid-19 vaccine continued to deliver strong efficacy results, showing 94% efficacy in the main analysis of its key study. The company said it would immediately seek regulatory clearances in the U.S. and Europe. The milestone suggests that there could be two vaccines against the SARS-CoV-2 virus before the end of 2020. Pfizer and BioNTech released positive results for a similar vaccine on Nov. 18, and requested an emergency use authorization, or EUA, from the FDA two days later.