A spokesman said Ardern's participation in events this week - including the Budget - would depend on whether she was well enough each day.
Last week while Ardern was isolating but before she tested positive for Covid-19 she chaired Cabinet remotely and took part in Parliament's proceedings.
Yesterday, it was revealed she tested positive for Covid-19 and had been symptomatic since Friday evening.
She has been in isolation since Sunday when her partner Clarke Gayford tested positive. Her daughter Neve tested positive on Wednesday.
"Despite best efforts, unfortunately, I've joined the rest of my family and have tested positive for Covid-19," she said.
"To anyone else out there, isolating or dealing with Covid, I hope you take good care of yourselves!"
The Prime Minister will be required to isolate until the morning of Saturday, May 21.
Travel arrangements for her trade mission to the United States are unaffected at this stage.
The Prime Minister is far from alone - more than a million Kiwis have tested positive for the virus since the pandemic began, although experts think the actual number of infections is double that number.
Among them are a slew of fellow politicians, including Luxon and Covid-19 Response Minister Chris Hipkins in March.
Former National leader Simon Bridges, Police Minister Poto Williams and MPs Tamati Coffey, Anahilia Kanongata'a-Suisuiki, Joseph Mooney, Penny Simmonds and Stuart Smith have also previously tested positive for Covid-19.
The Minister of State for Trade and Export Growth Phil Twyford, also tested positive for Covid-19 earlier this week.
Twyford tested positive from a RAT after beginning to feel symptomatic on Friday evening, and is displaying moderate symptoms, a spokesperson said.
As a result of Twyford's test result, he is no longer able to travel to East Timor on Monday, where he was to represent the Government at the 20th anniversary of East Timor's independence, and the inauguration of Dr Jose Ramos-Horta as East Timor's next President.
Environment Minister David Parker was the first New Zealand MP to test positive for the virus.
