The report, sent to state governors and dated Nov. 29, said that everyone over the age of 65 or with significant health conditions "should not enter any indoor public spaces where anyone is unmasked."
It also said that all Americans under 40 should "assume you became infected" if Thanksgiving gatherings involved anyone outside of their immediate families.
"You are dangerous to others and you must isolate away from anyone at increased risk for severe disease and get tested immediately," the report read.
SEE ALSO: Should you quarantine after Thanksgiving gathering amid rising COVID cases? Yes, expert says
As of Wednesday, the United States has confirmed more than 13.7 million coronavirus cases and 270,000 deaths, according to the John Hopkins University dashboard.
The country reported 177,000 new cases Tuesday, and more than 99,000 people are currently hospitalized with COVID-19 in the US, a new record.
The report said the COVID-19 risk to all Americans is at a "historic high."
"The national daily COVID incidence after Memorial Day, but before the summer surge, was fewer than 25,000 new cases/day and is now more than 180,000 new cases/day; COVID inpatients then were fewer than 30,000 but are now more than 90,000; fatalities have more than doubled. We are in a very dangerous place due to the current, extremely high COVID baseline and limited hospital capacity; a further post-Thanksgiving surge will compromise COVID patient care, as well as medical care overall," it read.