Health officials are poring over the medical records of thousands of children who were treated at a Pukekohe dental clinic to determine if any are harbouring serious diseases.
So far just 447 of the nearly 2500 children treated at the Pukekohe Intermediate dental clinic have had their health records, including immunisation charts, scrutinised.
A spokesman for the health board's chief medical officer said no children had yet been identified with any of the diseases at the centre of an emergency screening programme.
It's feared children treated at the dental clinic between September 13 and January 23 may have been exposed to hepatitis B and C and HIV because of malfunctioning dental equipment.
However, officials had only looked at the medical histories of children treated in January.
They were yet to look at the bulk of the 2000 children who were treated between September and December.
Only 25 children across the country have HIV and just six children in the northern region have hepatitis B.
The spokesman said the chances of one of those children being treated at the clinic was remote but the health board was taking a cautious approach.
He said the main concern was children not fully immunised against hepatitis B.
That group would be prioritised for follow-up treatment and parents encouraged to take their children for booster shots.