Acting Prime Minister Grant Robertson has tested positive for Covid-19.
The Deputy Prime Minister and Finance Minister - who is steering the country during Prime Minister Jacinda Ardern's trip to Europe - revealed his infection in a post on Instagram.
"I guess it had to happen eventually! Fairly mild symptoms, but will try to do right thing and get some rest," he said.
"Still Acting PM while I am compos mentis (some would say that is questionable at best of times!) but grateful to colleagues for stepping in for House and meetings today," he posted this morning.
Ardern ended her visit to the Nato summit this week in Madrid warning that the unstable international environment was not limited to Europe - she called out China for its recent challenging of international norms and Russia for its information warfare in the Pacific. "The shift in environment we are currently seeing is not limited to one region.
"In our neighbourhood, we see the mounting pressure on the international rules-based order. We see attempts to disrupt and destabilise – even New Zealand is targeted by Russian mis- and dis-information," Ardern said.
She added that "China has in recent times also become more assertive and more willing to challenge international rules and norms".
The Nato summit has been dominated by Russia's invasion of Ukraine, but the alliance also discussed a new "Strategic Concept", a document that sets out how Nato sees the world security picture. These are drawn up once every decade, and the new strategic concept, adopted at this summit, includes a strong rebuke of China's assertiveness.