“The absence of national leadership on Covid-19 is unprecedented and dangerous,” said the letter, signed by current and former officers of the CDC’s Epidemic Intelligence Service of outbreak investigators. “CDC should be at the forefront of a successful response to this global public health emergency.”

Signers included two former CDC directors: Jeffrey Koplan, who led the agency under Presidents Bill Clinton and George W. Bush, and Tom Frieden, who served under President Barack Obama.

All of the signatories were writing to “express our concern about the ominous politicization and silencing of the nation’s health protection agency” during the current pandemic, said their letter, which was published Friday in the Epidemiology Monitor, a newsletter for epidemiologists.