WASHINGTON - President Donald Trump's National Security Adviser Robert O'Brien has tested positive for the coronavirus — making him the highest-ranking official to test positive so far.That's according to two people familiar with the situation who spoke on condition of anonymity because they weren't authorized to discuss it by name.RELATED: Virus vaccine put to final test in thousands of volunteersThe White House confirmed that O'Brien has mild symptoms and “has been self-isolating and working from a secure location off site,” adding that: “There is no risk of exposure to the President or the Vice President" and that the "work of the National Security Council continues uninterrupted.”National Security Adviser Robert O'Brien speaks with.