Health experts criticise NZ's COVID-19 community transmission data as 'meaningless, uninterpretable'

Public health experts have told Newshub the Health Ministry's data on COVID-19 cases is meaningless and we haven't won the battle on community transmission. 

The concern is that in-depth, targeted community testing is still yet to begin. 

Auckland University School of Medicine Professor Des Gorman says we can't claim to have stopped community transmission.

"Quite frankly, given the way we've been reporting data and given the extent of testing we've done, I suspect that question [of stopping community transmission] is still to be answered," he says.

Another epidemiologist, Otago University Professor Nick Wilson, also agrees we are "some way" from being able to claim we've stopped community transmission because the level of testing in New Zealand has not been at a high enough level for long enough.

Another epidemiologist, who asked not to be named, agreed telling Newshub "we have not won anything yet".

It comes after Prime Minister Jacinda Ardern said on Monday we had won the battle against community transmission.

"There is no widespread, undetected community transmission in New Zealand. We have won that battle."

Health Minister David Clark reiterated that point on Thursday.

"We have collectively managed to stop community transfer of COVID-19 for now."

The Ministry of Health has an "uninterpretable" way to calculate community transmission, Gorman says.

The Health Ministry says it changed its method of reporting community transmission last week.

The way the data is gathered now is that if 'Person A' gets the virus from an unknown source and gives it to, for example, four other people, then only person A is classified as community transmission.

"I think it's uninterpretable and consequently it's meaningless and I think it profoundly understates community transmission," Gorman says.

There are six clusters in New Zealand where the origin is unknown. The clusters are Marist College, three rest homes, a stag party and a "community" cluster in west Auckland.

Only the first person in each of these clusters of "unknown" origin is considered community transmission. 

So total community transmission according to the ministry is four percent. This is a much lower figure than if we included everyone else in those clusters, which would make it 28 percent of all cases.

Even this week, the Marist cluster added another case, which Gorman says calls into question our so-called "gold standard" contact tracing.

"If they're confident that the community prevalence is trending to zero, and if they're confident they can track people within 48 hours, and if they're confident they can isolate cases, we should be at level 2. If we're not there, presumably one of those three platforms is yet to reach the stage of confidence," he says.

On Thursday, the message from the Prime Minister was that the COVID-19 struggle will be ongoing.

"This is going to be with us for a long time and we will have to keep winning battles every step of the way," Ardern says.

On Tuesday, when Newshub asked Dr Ashley Bloomfield if the way community transmission was being reported was misleading, he said it wasn’t.

However, a spokesperson pointed out that if the Ministry knows how transmission occurs through a cluster - for example through household contacts - then it's less of a concern.

The Ministry spokesperson told Newshub that's because "we have mechanisms for controlling the spread through close contacts being quarantined etc". 

This article was amended on May 1 because it stated one of the clusters was a community care provider. That cluster has now been reclassified by the Ministry of Health as a "community" cluster in Auckland and does not relate to one specific care provider.