The outbreak of gastrointestinal illness at Hotel Sofitel in Redwood Shores continued days after last month’s ill-fated NAACP dinner, leading the hotel to temporarily shut down all its food operations for disinfection.

The hotel and San Mateo County Health System confirmed Monday that additional people, including guests and hotel employees, became sick in the days after the NAACP State Convention on Oct. 25, when 12 people were taken by ambulance to hospitals for treatment of dehydration. Others drove themselves to the hospital the night of the gala or rode out the symptoms at home.

The cause of the outbreak remains under investigation. Hotel Sofitel spokeswoman Sandra Duhamel said foodborne illness and a norovirus are both possibilities. County environmental health investigators didn’t find any violations linked to foodborne illnesses, she said. The company hired an epidemiologist who said the symptoms, vomiting and diarrhea with recovery in 24 to 48 hours, indicated a possible norovirus.

The hotel has conducted a propertywide cleaning under the guidance of Belfor Property Restoration, said Duhamel, adding some of the food outlets are now back in operation. The hotel was open for business Monday, and a handful of guests were seen eating downstairs.