Pregnant people are at higher risk of severe COVID-19. This is a well-established fact. But it hasn’t always been. Earlier on, experts did not believe this group was at higher risk. This change in perspective is normal: in fact, it's how science works.
An epidemiologist breaks down the differences between short-term clinical trials and observational studies, and what each type of inquiry can tell us about how well vaccines work and how long they will last.