Covid-19 may have circulated in the community for weeks, New Zealand’s top health official said, as a ninth potential new case emerged overnight.
Dr Ashley Bloomfield, chief health officer, said a new case has been identified at the country’s second-largest school, Mt Albert Grammar, which hosts 3,000 students.
Bloomfield said isolation and testing of any close or occasional contact with positive cases was the main response to the outbreak, as was the search for the original source.
Genome sequencing was “well underway” on the four original cases, to trace the train of transmission, but he agreed that “it was possible” that the virus has been circulating in the community for weeks, as some experts. now suggest.
“We will find the source, I have no doubt.” Bloomfield told Radio NZ.
One of those infected worked at a cool store in Auckland, and it was also being investigated whether the virus was entering the country by imported freight, although health officials stressed that this scenario was “very unlikely.”
New Zealand health officials say it is only a matter of time before resolving the mysterious outbreak that has plunged the country’s largest city, Auckland, into lockdown for three days, while the rest of the country saw its alert level increased from 1 to 2.
New Zealanders were shocked by the return of the virus after 102 days without community transmission.
The discovery of four cases in south Auckland prompted Prime Minister Jacinda Ardern to place the country’s largest city on a 60-hour lockdown on Wednesday in an attempt to crush the spread.
Later Wednesday, four more probable cases were announced, all linked to the original family group, some of whom also traveled to the North Island resort town of Rotorua over the weekend.
On Thursday morning, local media reported a ninth case based on a notice sent to families in Mount Albert Grammar.
Bloomfield confirmed that a student, classified as close contact of the four existing positive cases, had tested positive.
The infected student attended class on Monday, and local health officials said they were contacting and isolating around 100 close contacts they had at school.
The process of contact tracing, isolation and testing is crucial in New Zealand which, unlike other countries, has pursued an elimination strategy for the virus.
It was successful in the fall, when a 51-day lockdown eradicated the virus from the community and allowed the Kiwis to resume their normal lives, outside of strict border controls.
The epidemic has also returned New Zealanders to a tradition of lockdown; pending Jacinda Ardern’s daily 1 p.m. press conference to find out the number of new cases.
The government will decide at a critical cabinet meeting on Friday whether to extend or deepen the lockdown, a decision largely based on the number of cases and whether the source case has been found. They must also consider whether to postpone a national election scheduled for September 19.
Finance Minister Grant Robertson said the government will also consider additional economic assistance for affected people and businesses as needed.
On Thursday morning, queues at test facilities began before dawn, with waits of up to six hours in some cases. Panic purchases of basic groceries continued and supermarkets have now issued purchase limits for certain items.
Police Commissioner Andrew Coster said most Aucklanders comply well with lockdown rules, although some have tried to flee the city for holiday homes on the coast, or even as far as the resort town of Queenstown on the South Island.
AAP contributed to this report