First Minister Nicola Sturgeon said the Scottish government was keeping an eye on Shetland as cases continue to rise.
Latest government figures show 25 cases have been recorded since Christmas Eve, with 14 recorded on Monday 28th December alone.
And Ms Sturgeon said that developments in the isles were being “very closely monitored”.
“We’re seeing quite a big number of cases in Shetland relative to its population,” she said.
Ms Sturgeon urged people not to visit other people’s houses, not even at New Year.
She will update Holyrood on any changes to lockdown rules on Wednesday afternoon.
NHS Shetland’s Elizabeth Robinson said on Monday it was now “almost certain” Shetland would be moved into tier four.