Traditional lab tests for blood-borne pathogens can take days to yield results. Karius has developed a liquid biopsy test based on metagenomic sequencing and machine-learning analysis of microbial cell-free DNA in the blood, allowing the company to detect over 1,000 pathogens from a single blood draw in just one day. Doctors are already using the Karius tests to detect infections in immunocompromised patients, and it can also be used to help drug researchers identify the right subjects for clinical trials and control infection-related side effects.