The Omicron variant of the coronavirus is incredibly contagious — it is able to infect people with even greater frequency than the Delta variant, and it is skilled at evading the immune system’s defenses. Much is still unknown about the new variant, and scientists are racing to understand its threat. But amid the uncertainty, there’s good news about a prospective new virus treatment: A pill by Pfizer is effective in reducing people’s risk of hospitalization or death from Covid-19. We explore these two developments and what they could mean for the next phase of the pandemic. Guest: Carl Zimmer, a science writer and author of the “Matter” column for The New York Times.