As the world focuses on Covid-19, influenza -- that other contagious respiratory illness caused by a virus -- seems to have all but disappeared. Flu activity is “unusually low” for this time of year, the Centers for Disease Control and Prevention (CDC) said in its weekly U.S. influenza surveillance report. Masking, social distancing, people with symptoms staying home and children not being in school are thought to be the drivers of the reduced flu transmission. Only 136 people were hospitalized for the flu between Oct. 1, 2020, and Jan. 16, 2021 (compared to 400,000 in the entire 2019-'20 season). The 136 hospitalizations was a small fraction of those in a normal flu season.