From JAMA:
Testing and infection.
Blue is PCR from nasal samples (this is the "gold" standard we are using when we swab your nose).

Pink is viral PCR from lung samples for those in the hospital.

Orange is whole virus recovered in the respiratory tract.

Yellow is viral PCR from stool

Purple is IgM immune response

Green is IgG immune response

The time course of PCR positivity and seroconversion may vary in children and other groups (the asymptomatic individuals who go undiagnosed).