New Zealand's supply of coronavirus test kits and swabs has come under scrutiny at the Epidemic Response Committee on Tuesday.
Director-General of Health Dr Ashley Bloomfield was grilled by Opposition MPs over the availability of nose swabs for GPs after several complained of a shortage.
National's Dr Shane Reti said he's been contacted by many people who have complained they're being turned away from testing facilities despite recommendations from their GPs.
Dr Bloomfield said it was very hard for him to second-guess the clinical judgement of either the GP or the person at the testing station.
"The testing stations are explicitly established to test and assess everybody who has symptoms and to apply the case definition," he told Dr Reti.
"It may be that not everybody is tested, but that doesn't mean that either the GP or the testing station has got it wrong."
International guidelines say the first-choice test for coronavirus is a nose swab, followed by a throat swab because the virus lives at the back of the nose. But Dr Reti said he's been told by doctors that they've run out of nose swabs, and DHBs have said there are supply issues.
"We don't have a problem with stock and supply chain of nose swabs and the issue may have been a distribution issue which we have pulled up into a national process," Dr Bloomfield replied.
"What I would say is you're correct - I wouldn't challenge you on that. A nasal swab is by far the preferred sample to get. If there is a shortage in any one place of the nasal swabs then the throat swab can be used but it's not ideal. Our aim is to make sure there is a good supply of both throat and nasal swabs."
Dr Bloomfield said he didn't have the figures for the ratio of nose to throat swabs.
National health spokesperson Michael Woodhouse said he was "staggered" to find laboratories are rationing which tests they do because they don't have the reagents and cassettes to test all the swabs coming in.
Health Minister David Clark said there have been "historic" challenges supplying these.
"The stocks of complete test kits has continued to grow," he replied. "They are challenging to acquire as Mr Skegg noted last week in the international environment, but we are acquiring more test kits.
"Where labs had a capacity constraint on test kits they were referring tests to other labs and they were working together."
But Woodhouse said these problems were only a few days ago.
"You can not deny the laboratories themselves were having to select which tests to do because of a shortage of testing material the needed."
Dr Bloomfield accepted there had been a shortage of reagent at Dunedin's Southern Community Laboratories last week, but this had been provided on Saturday.
He requested more details on any other people who were delayed in being testing because of a shortage in testing materials.