Stanford Radio

The Future of Everything with Russ Altman: E149 | Julie Parsonnet: How faith in herd immunity may be misplaced An expert in infectious diseases says that an undue focus on herd immunity could actually be doing more harm than good in the fight against COVID-19. Many have now become familiar with the term herd immunity, an idea few outside the infectious disease community knew just a few short months ago. It’s an elusive concept to comprehend, and harder still to achieve, but Stanford epidemiologist Dr. Julie Parsonnet says it’s important to understand just what herd immunity does – and doesn’t – mean for today’s pandemic. Broadly speaking, herd immunity is reached when enough people have either recovered from or have been fully vaccinated against an infectious disease and there are no longer enough susceptible people in the entire population (the herd) to sustain transmission. Herd immunity doesn’t mean there won’t be cases, only that when they crop up, they will then die out. Parsonnet says this term is