US Could Reach Herd Immunity but Struggle to Maintain It
Many experts believe the US is approaching a point at which enough people will have either gotten COVID-19 or been vaccinated that the coronavirus can no longer spread easily — the definition of herd immunity. But that threshold should never be thought of as a fixed goalpost, scientists say. And reaching it wouldn't definitively end the pandemic either. Rather, herd immunity in the US is a moving target that the country would have to work to maintain over time. "Technically, whenever we see cases going down, that suggests that there is enough population immunity or herd immunity to drive ca...