How Herd Immunity Works, a Possible Key to the Covid Pandemic’s End

There’s a consensus that the key to ending the coronavirus pandemic is establishing herd immunity. But there are many unknowns. One is whether researchers can develop a safe and effective vaccine. Another is how long people who’ve recovered have immunity; reinfection after months or years is common with other human coronaviruses. Finally, it’s not clear what percentage of people must be immune to protect the “herd.” That depends on the contagiousness of the virus.

For a QuickTake explainer on how and when the pandemic will end, click here.