At the beginning of the pandemic, almost exactly this time last year, we heard a lot of promises about the types of technology that could help us stop the spread of the disease. One of those tech miracles was thermal cameras — devices that could read someone’s temperature from a distance. Companies bought them in droves, thinking that installing them at the entrances of schools, airports or offices could stop sick people from entering. But do they work, and did they ever? Molly speaks with Conor Healy, the government director at IPVM, a video-surveillance research firm. He recently co-authored a study on fever-scanning devices and said many have one large flaw.