CHICAGO – On Monday, the U.S. Centers for Disease and Prevention announced the close of its investigation into Chipotle’s E. coli outbreak.

“We are pleased that the CDC has concluded its investigation, and we have offered our full cooperation throughout,” said Chris Arnold, Chipotle’s communications director, in a statement. “Over the past few months, we have taken significant steps to improve the safety of all of the food we serve, and we are confident that the changes we have made mean that every item on our menu is delicious and safe.”

Chipotle’s recent series of food safety outbreaks rattled its investors and enough of its customers to see visits decline, but the chain’s strong base of teens and young adult customers continued to support the fast casual chain, reports The NPD Group. 

“Young adults represent the largest share of Chipotle’s overall traffic,” said Bonnie Riggs, NPD Group’s restaurant industry analyst. “Their willingness to overlook any food safety concerns to eat at Chipotle could be a result of unabashed loyalty or lack of awareness.”

In the quarter ending December, during which several of the outbreaks occurred, total visits to Chipotle were down 5% compared to a 19% traffic gain the same quarter a year ago. Teens and young adults, however, increased their visits to the fast-casual chain by double-digits last year, according to NPD.

“What our research tells us is that Chipotle has a strong loyal base from which to build its business back up relatively quickly,” said Riggs. “To win back the trust of their former customers, Chipotle will need to continually communicate all of the ways in which they are preventing any future outbreaks and prove to them that they are able to deliver on their ‘food with integrity’ promise.”