The hasty reopening of businesses across much of the nation after the spring shutdown was largely blamed for a summer surge in infections, but social functions of various sizes among relatives, friends and co-workers may have been a contributing factor as well. Public health experts sound the alarm as the Labor Day weekend approaches. “People don’t think of it in the same way as the (President) Trump rally in Tulsa, a bunch of people on the beach or in the bars, but these small events add up to a lot. It’s just invisible,” said Dr. Peter Chin-Hong…