On Apr. 17, 2020, the University of Washington Medicine announced that a new clinical blood test will be conducted at the UW Medicine Virology Lab to check people for past infection with SARS-CoV-2. The test looks for the presence of an antibody, called IgG, which people produce in fending off the pandemic coronavirus.

The antibody first appeared several days or longer after a person contracts the virus, even in those who never had symptoms or had just mild to moderate respiratory illness.