Dr. Priya Sampathkumar gets asked by her two teen-aged sons every day when they can expect to see NBA games again. She’s among the doctors desperately trying to answer that question — and the NBA is now trying to help. Sampathkumar is on the staff at the Mayo Clinic, which is starting to get support from the NBA and its players for a study that will aim to shed more light on how antibody testing can help the medical world further understand COVID-19. NBA teams were told this week about the study through an invitation for players and staff to volunteer to take part.