VirScan works by detecting antibodies, immune system proteins that can latch onto specific spots on a particular virus and hasten its destruction. Antibodies remain in the blood for years after an infection, guarding the body in case that same virus returns.
VirScan's library already spans more than 1,000 strains of virus, whose genetic sequences are turned into little chunks of viral protein. When a blood sample is added to these protein chunks, antibodies in the blood latch onto any of the viral bits they recognize.