Wellington, 19 August 2021 (dpa/MIA) - New Zealand has approved the use of the Pfizer/BioNTech coronavirus vaccine for children and adolescents as it grapples with a Covid-19 outbreak, Prime Minister Jacinda Ardern announced on Thursday. The country entered a snap lockdown on Tuesday after a community-transmitted Covid-19 case was detected, the first in almost six months. The cluster, in Auckland, has now grown to 21 cases, with 11 new infections reported on Thursday. Ardern announced that 12-to-15-year-olds would now be eligible for the Pfizer/BioNTech coronavirus vaccine. "It's safe and it's the right thing to do," Ardern said. The vaccine was previously approved for people aged 16 and older. Two doses will be required, roughly six weeks apart. Ardern said health officials were now "fairly certain" they knew how and when the virus entered the country. Genome sequencing had linked the cases to a recent traveller from Sydney, Australia, who arrived in New Zealand on August 7. That person went into quarantine on arrival, and officials were still determining "some missing links" between the case and the new community cases. "I know we are all prepared for cases to get worse before they get better. However, today we believe we have uncovered the piece of the puzzle we have been looking for," Ardern said. More than 100 locations of interest have been identified, including a casino, high school, church, university and nightclub. With a population of some 5 million, New Zealand will remain in a hard lockdown until at least Saturday. The country has reported about 2,580 cases of Covid-19 since the onset of the pandemic, with 26 deaths.