"Save your business while saving lives," reads the website of Because Health, a Seattle tech start-up selling two types of tests to employers willing to pay $350 a pop to learn whether their workers have been infected with COVID-19. The company's "Workplace Health" plan includes not only nasal swab tests to detect infection, but also blood tests aimed at determining whether workers have developed antibodies to the virus -- and, possibly, future protection. "There's a tremendous consumer demand," said Dr. Lars Boman, the firm's Boston-based medical director. "Can they return to work? Can they return to life?"