President Donald Trump's national security advisor, Robert O'Brien, has tested positive for COVID-19, the White House said Monday. O'Brien, who holds a key role in the administration, "has been self-isolating and working from a secure location off site," the White House said in a statement. "There is no risk of exposure to the president or the vice president," it added, stressing that the work of the National Security Council continued uninterrupted. O'Brien travelled in mid-July to Paris, where he notably met with his French, German, Italian and British counterparts. Trump's national security advisor is the latest -- and most senior -- among several associates of the president to have contracted the novel coronavirus. In May, Katie Miller, Vice President Mike Pence's spokeswoman who is also married to Trump's close advisor Stephen Miller, tested positive for the virus. She has since returned to work. In early July, Kimberly Guilfoyle, a former Fox News television personality and the girlfriend of Trump's eldest son, Donald Jr, also tested positive. Guilfoyle has played a prominent role in fundraising for Trump's campaign for reelection in November. Trump has faced mounting criticism over his handling of the coronavirus outbreak, which has infected 4.2 million Americans and killed almost 150,000. jca/ec/jm