National's accused the government of botching its measles catch up campaign - which saw tens of millions of dollars spent - but reached just seven percent of its target.
The office of the Auditor General says Covid-19 and lockdowns materially affected the campaign.
But it also raised questions about a lack of targets and whether more thought should've been given to structuring funding to minimise waste.
Health Minister Ayesha Verrall says the campaign was disrupted "for understandable reasons".