US Defence Secretary Lloyd Austin says he has tested positive for Covid-19 and is experiencing mild symptoms and will quarantine at home.
It is the second time Mr Austin has contracted coronavirus.
In a statement, the 69-year-old said his is fully vaccinated and has received two boosters.
He said he will quarantine for the next five days in accordance with CDC guidelines and “will retain all authorities and plan to maintain my normal work schedule virtually from home”.
Mr Austin said his last in-person contact with President Joe Biden was on July 29.
In January, Mr Austin also contracted Covid-19 and had received a booster in October.
“Now, as in January, my doctor told me that my fully vaccinated status, including two booster shots, is why my symptoms are less severe than would otherwise be the case,” Mr Austin said.
“I will continue to consult closely with my doctor in the coming days.”
He added: “Vaccinations continue to both slow the spread of Covid-19 and to make its health effects less severe.
“Vaccination remains a medical requirement for our workforce, and I continue to encourage everyone to get fully vaccinated and boosted.”