LEBANON, N.H. — Dr. Anthony Fauci, the United States’ top infectious disease expert, warned against reopening schools in coronavirus hot spots.

Fauci, head of the National Institute of Allergy and Infections Diseases, spoke via video conference Monday to physicians and medical students at New Hampshire’s Dartmouth-Hitchcock Medical Center. He said while the nation’s “default principle” should be that children return to school, “to say that every child has to go back to school is not really realizing the fact that we have such a diversity of viral activity.”

He said there may be some areas where the level of virus is so high that it would not be prudent to bring children back to school.

Determined to reopen America’s schools despite coronavirus worries, President Donald Trump recently threatened to hold back federal money if school districts don’t bring their students back in the fall. He and top White House aides also have been ramping up attacks against Fauci, with Trump saying Fauci has “made a lot of mistakes.”