This winter, three major respiratory viruses — respiratory syncytial virus or R.S.V., the flu and the coronavirus — are poised to collide in the United States in what some health officials are calling a “tripledemic.”What does this collision have to do with our response to the coronavirus pandemic, and why are children so far the worst affected?Guest: Apoorva Mandavilli, a science and global health reporter for The New York Times.Background reading: Most cases of Covid, flu and R.S.V. are likely to be mild, but together they may sicken millions of Americans and swamp hospitals, public health experts warned.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.