Two key members of Prime Minister Jacinda's Ardern United States trip have tested positive for Covid, just two days from her scheduled White House meeting with President Joe Biden.

Top diplomat Chris Seed has tested positive for Covid-19, as has Ardern's chief press secretary Andrew Campbell.

"Both are isolating in San Francisco, where the Prime Minister departed from this morning," a statement said.

"The rest of the delegations is currently in air and en route to Washington DC. They produced negative RATS prior to leaving this morning. No one else in the delegation is
currently symptomatic.

"The New Zealand Embassy in Washington DC is in contact with the White House, but there is no change to meeting arrangements at this stage."

Seed, the chief executive of the Ministry of Foreign Affairs, has tested positive after landing in San Francisco last night on the way to Washington DC.

A spokesman said Seed had mild symptoms and had tested negative prior to today, including ahead of a meeting with California Governor Gavin Newsom two days ago.

Newsom announced on social media that he had tested positive for Covid-19 – a day after meeting with Ardern and her team, including Seed. Those meetings were all outdoors.

Jacinda Ardern and California Governor Gavin Newsom following the RX Joint Venture Signing in San Francisco. Photo / AP

It is the second known Covid-19 case in the PM's delegation after a person in the wider delegation tested positive earlier in the trip.

Seed was due to sit in with Ardern in her meetings with Biden and US Vice President Kamala Harris.

Ardern is unlikely to be affected, having only recently recovered from Covid-19 herself.

It is likely US Ambassador Rosemary Banks will sit in on those meetings in Seed's place and he will have to isolate in San Francisco for at least five days under US rules.

PM's press secretary has Covid symptoms

The PM's press secretary, Andrew Campbell, is also now showing Covid symptoms and has not travelled to Washington DC while he gets a PCR test to ensure it is not Covid-19.

Campbell has returned a negative rapid antigen test result and will fly to the capital city later if the PCR test is negative.

The PM's delegation has been travelling on the RNZAF Boeing in the US and has travelled to five cities in a busy schedule – it arrived in San Francisco after a day in Seattle which included meetings with technology companies and a social function.

The business delegation travelling with the PM left the trip to return to New Zealand from San Francisco last night.

Earlier this week, director general of health Ashley Bloomfield also tested positive while overseas – he had travelled to Geneva for a World Health Organisation meeting.

The PM travels to Washington today ahead of the meeting on Tuesday (early morning Wednesday NZ time). The US marks Memorial Day on Monday, a public holiday.

The pair are expected to discuss trade, China and possibly gun law reforms.