New Zealand Prime Minister Jacinda Ardern tested positive for COVID-19 with moderate symptoms, her office said in a statement on Saturday.
She will not be in parliament for the government's emissions reduction plan on Monday and the budget on Thursday, but "travel arrangements for her trade mission to the United States are unaffected at this stage," the statement said.
Details of the trip are still to be confirmed, although she is scheduled to deliver the commencement address at Harvard University on May 26.
Ardern had been symptomatic since Friday evening, returning a weak positive at night and a clear positive on Saturday morning on a rapid antigen test, it said.
She has been in isolation since Sunday, when her partner Clarke Gayford tested positive, it said.
Due to the positive test, Ardern will be required to isolate until the morning of May 21, undertaking what duties she can remotely.
Deputy Prime Minister Grant Robertson will address media in her place on Monday.
New Zealand enforced one of the world's most restrictive approaches to managing the initial COVID-19 outbreak in 2020, and its death toll of 892 remains among the lowest of developed nations.
However, it has experienced an Omicron surge since restrictions were loosened in March, with Ardern's positive case among more than 50,000 recorded over the last week.