WASHINGTON — The “upsurge” in respiratory illness in China is not from “a new or novel pathogen,” the director of the Centers for Disease Control and Prevention reassured members of Congress on Thursday.

The uptick can instead be attributed to existing viruses and bacteria, including Covid, flu, respiratory syncytial virus, or RSV, and mycoplasma pneumoniae, Dr. Mandy Cohen said, backing up the explanation offered by Chinese authorities and accepted by the World Health…