The prime minister of New Zealand confirmed that the coronavirus infections that triggered the country’s first lockdown in months are the UK variant, raising fears of a setback to the country’s previously successful fight against the disease. Jacinda Ardern said on Monday that no new community cases had been found since New Zealand’s largest city was placed into an emergency three-day lockdown on Sunday night, raising hopes that the lockdown would be short. “We were right to take a cautious approach and focus on safety because we’ve confirmed it is the UK variant,” she told Radio New Zealand. “This is a highly transmissible and a fast-moving strain, one that requires extra care in order to stamp it out, and this is exactly what our approach entails,” she added. It is the first time the more infectious UK variant has been found in New Zealand, which has achieved one of the lowest infection rates in the world thanks to strict border controls. Three people – a mother, father and daughter from the same Auckland family – tested positive for coronavirus over the weekend. The mother works at Auckland’s international airport for a company that does laundry for international aircrew. Initial speculation had focused on the strain escaping from a quarantine hotel, but Mrs Ardern said genome sequencing of the latest case had failed to “link it to any of the cases we’ve had come through our managed isolation facilities … it tells us it wasn’t someone who went from an airline into our managed isolation.” She said investigations tracing the source were focusing on three scenarios, including whether the variant arrived with a transit passenger who stayed airside at the airport, or international aircrew via a uniform cleaned by the laundry company. She said the third scenario, that the infection had come from an unsequenced patient at a quarantine hotel, was unlikely because difficulties with sequencing had generally been associated with older cases of infection. Auckland’s 1.6 million people were told to stay at home for three days from midnight on Sunday. Under tier three of the country’s four-level lockdown system people must stay at home in their household bubbles and public venues have to close. Schools will be closed except for children of key workers. Essential shops like pharmacies and food shops are allowed to remain open for face-to-face contact but must follow social distancing. Gatherings of up to 10 people are allowed for events like funerals. The rest of the country has been put into tier two, which requires people to wear masks on public transport and observe social distancing. New Zealand is one of the only countries in the world to have largely stamped out Covid-19 in the community, thanks to a combination of strict domestic lockdowns and stringent border controls. Entry to non-citizens has been closed since March. Citizens returning from overseas must spend a fortnight in a quarantine hotel. In late January the country confirmed its first case of the South African variant in the community in a 56-year-old woman who had recently returned from Europe. Health Minister Chris Hipkins said that case was probably contracted during the woman’s hotel quarantine. She only tested positive 10 days after she was released.