Switzerland cancelled training on Monday after 19 players and staff members reported stomach problems.
The Swiss started their Women's Euro 2022 campaign with a 2-2 draw against Portugal on Saturday and are due to face Sweden in their second Group C game on Wednesday.
However, their preparations for that match at Bramall Lane have been disrupted due to eight players and 11 staff members being forced to isolate with gastrointestinal symptoms.
The Swiss Football Association confirmed in a statement that the players affected are Eseosa Aigbogun, Svenja Folmli, Seraina Friedli, Rahel Kiwic, Lara Marti, Sandrine Mauron, Julia Stierli and Riola Xhemaili.
The affected players and staff members will remain in isolation until they no longer show any symptoms.
Swiss team doctor Martin Schober said: "The cause of the gastrointestinal problems cannot be conclusively clarified from the current situation.
"The symptoms of vomiting and diarrhoea are severe, but so far mostly brief. Some of them had only mild symptoms or no symptoms as early as this morning.
"If everyone is symptom-free tomorrow, we can travel to Sheffield as planned. Otherwise, further investigations are required."