The Ministry of Health says the individual flew from Rotorua and arrived in Blenheim on October 21.
He sought a test upon arrival after developing a sore throat. The positive case is likely linked to the Te Awamutu cluster.
There was no good news for Auckland or Waikato either on Saturday; 91 cases were reported in Auckland and eight in Waikato. There were also four in Northland, including two children under 12, and the and single South Island case in Nelson-Marlborough.
Professor of Public Health Michael Baker said officials should start thinking about measures to limit inter-island spread of Covid-19.
"Fairly obviously, it would be good to think about a very proactive policy to limit transmission now from the North Island to the South Island."
A single isolated case flying to Blenheim should be quite manageable, provided contact tracing was "very rapid".
The Blenheim case illustrated the challenge of trying to contain the outbreak where there was ongoing transmission, Baker said.
"It does mean the system will have to remain very vigorous if it's to avoid this virus transmitting throughout New Zealand, which it could do quite quickly. It does mean we need a very vigorous effort to stamp out the remaining chain of transmission in Waikato.
“If transmission becomes well established in Waikato, it's obviously much harder to maintain a boundary around there."
University of Auckland microbiologist Associate Professor Dr Siouxsie Wiles said the case showed why the South Island had not been put at alert level 1, and it was a wake-up call for the south.
Marlborough economist Alistair Schorn said the positive case came at an unfortunate time for businesses, many of which were expecting additional visitors due to the Labour Day and Marlborough Anniversary (November 1) long weekends.
"The main thing is people are going to that much less inclined to have face-to-face contact with others until they know how and when this is going to shake out ... This 'basic hesitance' will have some effect on normal economic activities, but how big or small is yet to be determined.”
The surge in cases in the past week is putting pressure on Auckland’s hospitals with 55 people now hospitalised with Covid, including 8 at North Shore Hospital, 19 at Middlemore, 27 at Auckland hospital and 1 at Waikato.
There are five people in ICU.
Last week the Nurses Organisation warned the country was “dangerously unprepared” for a potential tsunami of community Covid cases.
It said there were around 3500 nursing vacancies nationally across the health sector and training for nurses to pick up intensive care duties had been “woefully inadequate”.
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