Donald Trump Jr has tested positive for coronavirus.
“He’s been completely asymptomatic so far and is following all medically recommended COVID-19 guidelines,” the spokesman said.
It comes just after Andrew Giuliani, the son of Mr Trump’s personal lawyer Rudy Giuliani, announced he had tested positive.
Other members of Mr Trump’s inner circle to have contracted the virus in recent weeks include White House chief of staff Mark Meadows, Housing and Urban Development Secretary Dr Ben Carson, and top aides David Bossie and Corey Lewandowski.
The US is currently experiencing a fresh rise in COVID-19 cases as the country heads into the holiday season.
The country has recorded more than 1.1 million new cases in the last week, according to Centers for Disease Control and Prevention.
Presumptive President-elect Joe Biden has warned of a “dark winter” and urged Americans to re-think their Thanksgiving plans.
Meanwhile, Reuters reported on Friday that drug giant Pfizer was applying to US health regulators for an emergency use authorisation of its COVID-19 vaccine.
At a press conference on Thursday, Mr Biden insisted he would not seek to order a nationwide lockdown.
That came days after his coronavirus adviser, Dr Michael Osterholm, warned of “COVID hell” and advocated a total lockdown “for four to six weeks”.
“Everybody asks that question every single time,” an annoyed Mr Biden said.
“The answer was I would follow the science. I am not going to shutdown the economy, period. I say it again. No national shutdown. No national shutdown.”