Oslo, 4 August 2025 – Oslo Municipality has confirmed a hepatitis A outbreak tied to Frognerseteren Restaurant in Holmenkollen, and public-health officials are urging anyone who dined or worked at the landmark café between 15 July and 28 July to monitor themselves for symptoms and, if unvaccinated, contact their doctor immediately.
Eleven laboratory-confirmed cases have been recorded since last Wednesday, and Oslo’s chief medical officer, Dr. Anne Lise Ryel, says the number is expected to rise. “All patients either ate at or worked at Frognerseteren in the past three weeks,” Ryel told reporters at a hastily convened press conference Monday morning. “The pattern is unusually tight, which suggests a common food-borne source.”
The iconic timber-framed restaurant, perched above the city with panoramic fjord views, voluntarily closed its doors on Sunday evening after the first two infections were traced back to its kitchen. Frognerseteren’s management said in a statement that a staff member who handled cold prepared dishes tested positive for hepatitis A last week, and follow-up testing identified viral RNA in samples of a house-made shrimp mayonnaise served during the second half of July.
“We are devastated that our guests and employees may have become ill,” said Frode Andersen, Frognerseteren’s general manager. “We have discarded all potentially affected products, undertaken a deep clean of the kitchen, and are cooperating fully with the Norwegian Food Safety Authority and the municipal health department.”
Hepatitis A is transmitted primarily through the “faecal-oral” route—often via contaminated food handled by an infected person who has not followed proper hand hygiene. The virus has an incubation period of 15–50 days; early symptoms include fever, fatigue, loss of appetite, nausea, and jaundice. Most adults recover fully within two months, but the infection can be more severe in people with underlying liver disease or compromised immune systems.
Oslo’s health agency has launched a city-wide vaccination campaign for restaurant staff and is offering free post-exposure prophylaxis—vaccine or immunoglobulin—to anyone who ate at Frognerseteren between 15 and 28 July. Residents can book a slot through the municipality’s online portal or by calling the outbreak hotline (22 80 50 00).
Norwegian Food Safety Authority inspectors have seized remaining food stocks and are reviewing supplier records to determine whether contaminated shellfish or produce may be implicated. The agency is also auditing hygiene routines and staff training records. Preliminary findings indicate that while the restaurant’s temperature logs were in order, a temporary worker who began in mid-July had not yet completed mandatory hygiene certification.
Local reaction has been swift. Social media groups devoted to Oslo dining buzzed over the weekend with worried patrons sharing dates of recent visits. “We celebrated my mother’s birthday there on the 24th,” said Ingrid Halvorsen, a resident of Nordstrand. “Everyone in our party is vaccinated, but it’s still unsettling.”
Frognerseteren, which dates back to 1891 and is famed for its cloud-berry waffles and sour-cream porridge, typically draws thousands of hikers, skiers, and tourists each week. Andersen says management is “exploring options” to reopen once health authorities give the all-clear, but no date has been set.
For now, city officials are urging calm. “This is a contained outbreak,” Dr. Ryel emphasized. “With prompt vaccination and careful monitoring, we can prevent further spread.”
Anyone who develops symptoms is advised to stay home, avoid preparing food for others, and seek medical attention. Updates on the investigation and vaccination clinics can be found at oslo.kommune.no/hepatitisA.