One new case was identified in the outbreak late on Saturday night, bringing the total to 48 cases. The newest case was a contact of a previously-identified patient.
NHS Western Isles Chief Executive Gordon Jamieson urged island residents not to become “complacent” as the outbreak continues despite small case increases each day.
Over ten per cent of the island, whose population is just over a thousand, have been asked to self-isolate since the outbreak began.
As the island has limited healthcare facilities, serious Covid-19 cases must be evacuated by air.
Mr Jamieson announced the new cases in an update late on Saturday night.
"We have had one new positive case of Covid-19 here in the Western Isles,” he said.
"The case is a contact of an existing case and is on Barra. That brings the total number of cases on Barra associated with this outbreak to 48.
"Whilst the new positive case numbers on a daily basis are diminishing, I have to let you know that tonight since the outbreak began, our fifth emergency retrieval is underway from Barra. Our thoughts go out to that patient and their family.
"Our message to the wider public is please do not get complacent. Please continue to follow the rules,” he said.
Barra, along with Vatersay, was moved to Level four restrictions last week in light of the outbreak.
Like other island areas the communities had previously been in Level three.
There have been some delays to processing of Covid-19 tests from Barra in recent days, as they must be transported from the island to a lab in Stornoway for testing.
NHS Western Isles thanked the Coastguard rescue teams in Barra, Lochboisdale, Stornoway and Harris, which are assisting with the transportation of tests.
Chief Medical Officer Dr Gregor Smith said last week that the Barra outbreak was being monitored “very closely” by the First Minister and an Incident Management Team.
“The First Minister and I have had some preliminary discussions about it, and we will continue that discussion with ministers and officials,” he said.