'I didn't think it was a big deal,' Clinton says of pneumonia bout

U.S. Democratic presidential candidate Hillary Clinton leaves her daughter Chelsea's home in New York, United States September 11, 2016, after she left ceremonies commemorating the 15th anniversary of the September 11 attacks feeling 'overheated.'

Democrat Hillary Clinton said on Monday she could resume presidential campaigning in a couple of days after a bout of pneumonia that she initially had not believed was "that big a deal."

Clinton's health scare after she almost collapsed at an event on Sunday, causing her to cancel some campaign trips, revived concerns about a tendency toward secrecy that has dogged her campaign, and underscored perennial worries about the medical fitness of candidates for one of the world's most demanding jobs.