HERD IMMUNITY: Population immunity is slowing down the pandemic in parts of the US. “The US has been recording more than 1,000 covid-19 deaths and 45,000 confirmed cases a day. The flip side of the rapid spread, however, is there are progressively fewer vulnerable people to catch and spread the virus again. Researchers say they hope to determine how great a role the rise of this population immunity can play in managing the pandemic.”