A survey by the Centers for Disease Control and Prevention found that 54% of people infected with coronavirus were unable to pinpoint who may have infected them.

Only 46% reported recent contact with a COVID-19 patient. Most participants’ contacts were a family member (45%) or a work colleague (34%). Two thirds of participants were employed; only 17% were able to telework.

Outpatients were more likely to report being employed than were inpatients (70% versus 42%) and interacted with persons outside the home more frequently. Among employed participants, 25% reported working in health care.

The survey notes that case investigation, contact tracing and isolation of infected persons are needed to prevent ongoing community transmission, given the frequent lack of a known contact. Enhanced measures to ensure workplace safety, including social distancing and more widespread use of cloth face coverings, are warranted.

According to the report, "The wide range of symptoms reported, and the lack of known COVID-19 contact in 54% of patients, underscores the need for isolation of infected persons, contact tracing and testing during ongoing community transmission, and prevention measures including social distancing and use of cloth face coverings."