Breakthrough cases of COVID-19 seem to be more prevalent than ever. But just how common — and how dangerous — are breakthrough cases? And can they be prevented? To get the facts about COVID-19 breakthrough cases, we talked to infectious disease expert Steven Gordon, MD. He explains what they are, why they happen and whether vaccines are still effective (spoiler: They really, really are).  Breakthrough cases of COVID-19 seem to be more prevalent than ever. But just how common — and how dangerous — are breakthrough cases? And can they be prevented? To get the facts about COVID-19 breakthrough cases, we talked to infectious disease expert Steven Gordon, MD. He explains what they are, why they happen and whether vaccines are still effective (spoiler: They really, really are).  Breakthrough cases of COVID-19 seem to be more prevalent than ever. But just how common — and how dangerous — are breakthrough cases? And can they be prevented? To get the facts about COVID-19 breakthrough cases, we talked to infectious disease expert Steven Gordon, MD. He explains what they are, why they happen and whether vaccines are still effective (spoiler: They really, really are).