What is “herd immunity” and when will we get there?

Herd immunity means that enough people in a community are immune to a disease that the disease can’t spread easily among them. That helps protect people who are not immune—for example, those who can’t be vaccinated for some reason—from getting sick. In the case of COVID-19, we don’t yet know how many people need to be vaccinated to reach herd immunity. But we are likely still far away from that point.