Canterbury DHB's Emergency Coordination Centre controller Dr Helen Skinner confirmed yesterday afternoon two Chatham Island residents had tested positive.
They were isolating and being supported on the island, she said in a statement.
"We encourage anyone who isn't vaccinated or hasn't had their booster to get vaccinated as soon as possible - the Chatham Islands Health Centre will be offering vaccinations tomorrow."
The DHB would be distributing RAT tests to all households on the islands early this week, as a precaution to allow early detection of positive cases, Dr Skinner said.
"We encourage anyone who has symptoms to have a RAT test and report their results to My Covid Record. Any positive results should also be reported to the local health centre so that we can support follow up."
The Chatham Islands launched a mass vaccination programme last year.
When that was announced, health officer Ralph LaSalle said the idea was to protect the entire islands.
"Given the remote location of the islands and the small population, we are vaccinating the whole community at once because this is more efficient and will make best use of our resources."
The Chatham Islands are provided health services through the Canterbury District Health Board.
Of the 638 people who live on the islands, only 56 percent are boosted, compared to the national average of 73 percent.
