Multiple outlets report that foodborne illness outbreaks linked to large restaurant chains are rare, even though such incidents can still occur and cause illness among customers. The coverage highlights that when outbreaks are reported, they can create major disruptions for the affected businesses, including customer concern and operational impacts, despite the low overall frequency of chain-related cases. Sources note that major restaurant companies are not immune to public-health risks, but routine food-safety controls and oversight typically help prevent widespread outbreaks. At the same time, the reporting emphasizes that illnesses can still surface when contamination occurs or when food handling and hygiene procedures fail at specific locations. The articles also point to the broader context of foodborne illness reporting: investigations may take time, and not every illness is definitively tied back to a particular restaurant. Overall, the sources agree that while restaurant-chain-linked foodborne illnesses do not happen often, they can still lead to customer sickness and significant business fallout when they do.