Some UV light devices do claim to use UV-C rays. But Mia Lieberman, PhD, a clinical veterinarian at Harvard Medical School who's studied one such product, told CNN that the light may not be intense enough to work against COVID-19. "I don't think consumers should rely on a UV device that's commercially available to eradicate coronavirus on their phone," she said. "I don't think we have the data to know how much it helps."