The new coronavirus has upended all of our usual calculus about seemingly ordinary activities. Is running past someone on the street safe? How about shopping in a grocery store with a 6-foot (2 meters) distance? And what about packages and takeout? And which of these activities poses the biggest risk?Unfortunately, there’s a lot we still don’t know about the way the virus that causes COVID-19 spreads.”At this point, I don’t think anyone can take a group of people with COVID, say how each person has become infected, and then say that xx% got infected with droplets and yy% got infected via touching surfaces,” Dr. Jeffrey N. Martin, a professor in the Department of Epidemiology and Biostatistics at the University of California, San Francisco, told Live Science in an email. “I don’t think this kind of study has ever been done for any infection. In most individual persons, we do not know how the person got infected.