Vilsack recently traveled to Mexico to discuss trade policies between the US and Mexico.
He is not considered a close contact of President Joe Biden, per a White House official.
Garland, Raimondo and Pelosi announced their positive tests after attending the elite Gridiron Club Dinner in Washington last Saturday. President Joe Biden did not attend the dinner.
Dinner attendees had their vaccination status checked, but were not required to show proof of a negative Covid-19 test for entry.
This story has been updated with additional details.