National security adviser Robert O’Brien has tested positive for COVID-19, a White House official confirmed on Monday.

"National Security Adviser Robert O’Brien tested positive for COVID-19. He has mild symptoms and has been self-isolating and working from a secure location off site,” the official said in a statement.

“There is no risk of exposure to the President or the Vice President," the official added. "The work of the National Security Council continues uninterrupted."

The positive test makes O’Brien the highest-ranking White House official to date to test positive for the virus, which has infected more than 4.2 million Americans and killed more than 145,000 people in the U.S.

O’Brien, tapped as national security adviser last September, is one of President Trump’s most trusted advisers. He meets regularly with Trump to brief him on national security matters and, as a result, is tested for the coronavirus daily.

O'Brien traveled earlier this month to Europe to meet with his counterparts from France, Italy, the United Kingdom and Germany. He often travels with Trump, including making a July 10 trip to U.S. Southern Command headquarters in Doral, Fla., for a briefing on counter-narcotic operations.

He is also a member of the White House's coronavirus task force, which meets at least once a week. It was not immediately clear when O'Brien last attended a task force meeting in person.

Bloomberg News first reported O’Brien had tested positive. According to the news outlet, O’Brien is believed to have contracted the virus while taking some time off from work and has been out of the office since late last week.

White House economic adviser Larry Kudlow told reporters Monday that he spoke to O’Brien on Friday and said he believed O’Brien’s daughter was sick prior to him contracting the disease. Kudlow said he hadn’t spoken to O’Brien on Monday and couldn’t confirm that he had tested positive.

The case is the latest instance of the coronavirus reaching the White House, which has taken precautions in order to keep the president and vice president safe, including testing everyone who comes in close contact with them. However, the White House has done away with some measures implemented to prevent the spread of COVID-19, including removing a requirement for staff members to wear masks and stopping temperature checks for those entering the White House complex.

One of the president’s military valets and the vice president’s press secretary previously tested positive for the virus. Kimberly Guilfoyle, who is a top Trump campaign official and is dating Donald Trump Jr., also tested positive earlier this month.

Last week, a cafeteria employee working in the Eisenhower Executive Office Building tested positive for the virus, as did a U.S. Marine assigned to Trump’s helicopter squadron ahead of the president’s planned trip to his Bedminster, N.J., golf club.

--Updated at 12:16 p.m.