Former New Jersey Gov. Chris Christie checked himself into Morristown Medical Center Saturday afternoon as a “precautionary measure” following his positive coronavirus test result.

In a tweet, he said has “mild symptoms” and went to the hospital due to his “history of asthma.”

Christie, Trump’s former 2016 rival, told The Associated Press on Friday that the last time he was with the president was Tuesday during preparations for his debate with former Vice President Joe Biden in Cleveland. Christie had tweeted Friday morning that he had last tested negative ahead of Tuesday’s debate and was not having any symptoms then.

Christie is the latest person who has been in close contact with the president recently to test positive for the virus. In addition to Trump and first lady Melania Trump, multiple people who have traveled with Trump or attended events with the president have contracted the virus over the last several days.