On the increase, however, are cases of the more contagious variant first identified in Britain, which have doubled in the United States every 10 days, according to the Centers for Disease Control and Prevention. The instances are still low, but climbing. Only 293 cases were reported in late January. By Feb. 4, there were 611, and the number now stands at 1,168.
Scientists have been split about the reasons for the drop, citing increased vaccinations, decreased testing and the seasonal patterns of these kinds of viruses, whose transmission rates decline as the winter goes on. Others have suggested it’s because people are getting better at following social distancing restrictions.
Here are some significant developments: