We May Never Know How Many People Have the Coronavirus

New studies underscore why poor testing capacity is such a risk

Someone who has coronavirus is supposed to quarantine at home for 14 days. Someone who doesn’t have symptoms but has been credibly exposed to the virus — like has a close contact with the disease or has traveled to an area where the virus is spreading — is also supposed to quarantine.

However, growing data suggests the number of people with mild symptoms who were never diagnosed with Covid-19 and infected…