Chipotle Mexican Grill has health professionals on hand to diagnose workers calling in sick as truly ill, and not just taking a paid day off to nurse a hangover, its CEO, Brian Niccol, told an investors conference this week.

"We have nurses on call, so that if you say, 'Hey, I've been sick,' you get the call into the nurse," Niccol told a Barclays webcast on Wednesday. "The nurse validates that it's not a hangover — you're really sick — and then we pay for the day off to get healthy again."

The CEO detailed steps taken to recover the trust of customers after a slew of high-profile safety scares that battered Chipotle's brand and led Niccol's predecessor, Steve Ells, to step down in late 2017.

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Starting in 2015, an E.coli outbreak forced the closure of dozens of restaurants in Oregon and Washington and norovirus sickened more than 100 patrons in Boston. The chain last summer closed an Ohio restaurant for a day of cleaning after 647 customers became ill due to what health officials determined was due to a toxin that occurs in food left at unsafe temperatures.

But Chipotle handles things differently these days in its 2,500 restaurants, acccording to Niccol. "We have a very different food-safety culture than we did two years ago," he said. "Nobody gets to the back of the restaurant without going through a wellness check."

The efforts to safeguard against illness extends beyond encouraging sick workers to stay home to trying to ensure germs from customers don't spread, according to Niccol, who came to Chipotle nearly two years ago from Taco Bell.

Tables at Chipotle restaurants these days are cleaned with a norovirus-killing cleaner, Niccol said.

"There's probably people in here that might have the common cold. Even if we clean up after you, and we don't use a cleaner that kills that germ, it hangs around for the next customer," he said. "Even though our team member did nothing wrong — there was nothing wrong with our food — we have to hold ourselves to a higher standard to make sure that the dining room gets sanitized in a way that it hasn't been in the past."