Two staff at HMP Northumberland have tested positive for Covid-19.
However, the private prison's operator, Sodexo, insists "no prisoners have tested positive" in light of the new cases.
During the pandemic, Britain's prisons have become infection hotspots, with the enclosed space proving a ripe breeding ground the virus to spread.
Some jails - including HMP Northumberland - stopped visits at the peak of the pandemic, before eventually easing restrictions over the summer.
However cases have once again surged across the North East, including in Northumberland.
Back in July, the region was averaging less than two cases a week. Over the last seven days, there have been 580 cases.
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And confirming the two new cases, a spokesperson for the Acklington prison said: "We are working fully to guidelines issued from Public Health England, HMPPS and Sodexo and the necessary measures have been put in place to minimise the spread of infection."
The Category C jail traditionally houses around 1,300 inmates. Many are locked up for less serious, non-violent, crimes and are deemed low risk.
Earlier in the pandemic, low-risk prisoners nearing the end of their sentence were given early release as part of Government measures to try and stop the virus spreading in cramped conditions.
That paused in August by officials who claimed - back then - that the virus was under control inside Britain's jails.
