Even though more people are being vaccinated in the Blue Ridge Health District each week, doctors at UVA Health are worried about a potential fourth wave of the coronavirus. “At most, about half the population has some level of protection against COVID either from vaccination or from natural infection. That’s a half glass full, half glass empty proposition,” Dr. Costi Sifri, an infectious disease doctor at UVA Health, said. “There are places in the U.S. – in Michigan around Detroit and the New York City area – where we are seeing increased case counts and those have been trending up for the la...