At the beginning of the pandemic, the coronavirus looked to be another respiratory illness. But the virus has turned out to affect not just the lungs, but the kidneys, the heart and the circulatory system — even, somehow, our senses of smell and taste. Gina Kolata writes in the New York Times that now researchers have discovered yet another unpleasant surprise. In many patients hospitalized with the coronavirus, the immune system is threatened by a depletion of certain essential cells, suggesting eerie parallels with HIV. The findings suggest that a popular treatment to tamp down the immune system in severely ill patients may help a few, but could harm many others.