A Covid-19 modeller says it will be a minor miracle if new cases in Waikato do not spread more widely.
Three cases have been found from a house in the Firth of Thames - a level 2 area where a man was bailed from prison in Auckland.
Professor Michael Plank told Morning Report it looks like household members were infectious in the community for about a week.
He said officials need to see a lot of test results to gauge how far the virus may have spread.
He said it will be risky to move Auckland down alert levels at this point.
