Twenty-eight prison officers have been told to stay at home after a colleague tested positive for Covid-19.
The Government of Jersey said no prisoners at the island’s HMP La Moye had been affected by the case.
The infected person is following public health guidance and isolating with the rest of their household, officials said.
All social visits have been suspended for prisoners while contact tracing is under way, the government said.
It is the first case of coronavirus to be linked to Jersey’s only prison.
Nick Watkins, Acting Governor of the States of Jersey Prison Service said it was “well-prepared” for the staff absences.
Gaps in staffing would be covered by officers not affected by the case, the government said.
It added there was “no evidence” the virus was active in the prison population.
Prisoners will be allowed to video call or use in-cell mobile phones to contact their friends and family while visits are suspended.