Copy shortlink: Each week, more than 500 people make their way to Weyerhaeuser Hall on the Macalester College campus in St. Paul, where they swab the insides of their lower nostrils under medical supervision to get tested for COVID-19. The students and employees, selected semi-randomly by a computer to provide nasal samples for COVID testing, have no symptoms of the disease and no reason to suspect they're infected. And that's the point. When COVID-19 case counts fall, doctors and public health officials say the importance of finding and isolating asymptomatic carriers will re-emerge as a top priority for ending the pandemic. An analysis published last month in JAMA Network Open estimated more than half of all COVID-19 transmission originates in people who don't know they are infected.