Covid 19 coronavirus: Derek Cheng - The Covid data problem hindering Jacinda Ardern's big call on Monday

COMMENT

The key to having the country waltz into nationwide lockdown with little to no grumbles was "sharing all of the information", according to Jacinda Ardern.

With this knowledge, the public are more inclined to trust in the PM and docilely follow wherever she leads them.

So, as people start to get itchy lockdown feet in the lead up to Cabinet's decision on Monday, you'd think there would be a concerted effort to give us the fullest Covid-19 picture possible.

But we are still in the dark on many questions that Covid data should be able to answer, begging the question: will Cabinet's huge decision be similarly hamstrung?

The crux of the matter is articulated in a blog by Otago University public health experts: "It is still unclear from the Ministry of Health website as to the extent to which new cases of Covid-19 in the last 24 hours or last week ... have no known source."

The Ministry has dutifully informed us every day of the number of new cases, including the good news of no new cases in the past two days.

But in health chief Ashley Bloomfield's own words, it's "just one moment in time". The real deal is the overall trend - not only in the case numbers, but the types of cases and how they've changed over time.

If there were 10 new cases, for example, but they were all safely quarantined at the border, then the threat of an outbreak is minimal to none.

Otago University epidemiologist Professor Michael Baker is one of three public health experts calling for Covid-19 data to be presently in a more meaningful way. Photo / Supplied

As blog authors Gordon Purdie, Nick Wilson and Michael Baker say, data presented well can shed light on possible community transmission as well as any cracks in our elimination plan.

Any international air crew with the virus or any case linked to an infected overseas arrival would show a weakness in border measures.

Data on Kiwis who caught Covid-19 from someone who wasn't linked to an imported case would shed light on contact-tracing capacity.

A nurse testing positive would reveal a failure of containing infection in hospitals, while a positive test from an asymptomatic group could be a sign of a previously undetected chain of transmission.

The change in these numbers over time would show if our border measures were working, if our contact-tracing was improving - as Bloomfield has claimed - and whether we needed more protection for hospital staff.

The most critical category are any cases where the source of infection is unknown. As Ardern and Bloomfield have repeatedly told us, these are the most dangerous because there might be branches of transmission that are harder to identify, trace and isolate.

In looser alert level restrictions, one undetected case could quickly become dozens of cases.

There were only two cases with an unknown source of infection when the PM first made the call to move us all into nationwide lockdown.

It would be far more useful for the ministry to give us a daily update on these specific cases, and the trend over the past day, week and 28 days (two 14-day incubation cycles).

Trying to find this information has been, to put it mildly, challenging.

In one exchange I had with the Ministry of Health three weeks ago, I was told there were 30 such cases and they were classified as "community transmission". But according to the ministry website, there were meant to be 42 community transmission cases at the time.

Asking how 30 aligned with 42 led to a response that they were not, in fact, community transmission, but classified under "source under investigation". But there were also meant to be 42 of these cases at the time, which begged the same question.

Eventually the ministry seemed to realise that its classifications were not very useful, and they were changed to include a category of locally-acquired cases with an unknown source of infection - but with no timeline.

They currently make up 4 per cent of all cases, or about 60 cases in all, but many of them are no longer active because of the success of the lockdown.

The only way to find out the number of recent cases, it seems, is to ask Bloomfield directly at his press conferences - and he has always provided answers, suggesting that the data is there but a decision has been made not to publish it on the ministry website.

Director General of Health Ashley Bloomfield says a day of no new cases is just "one moment" in time. Photo / Mark Mitchell

This also means, incredulously, that public health experts wanting this information have to watch the press conferences in the hope that the question is asked and Bloomfield has an answer.

Some of these experts are even advising Bloomfield on the threat of Covid-19 in New Zealand.

Even when Bloomfield provides answers, it can be confusing. He has revealed that some cases have popped up in Timaru, Whanganui, and Te Puke.

Yesterday he said there were two unresolved cases: one in Nelson-Marlborough and one from the workforce at Auckland Airport. But there's no explanation about what happened to the Te Puke, Whanganui, or Timaru cases. Does that mean they've been resolved? If so, how?

The ministry's data issues are not new.

At the end of March, it quickly backtracked after it stopped giving daily updates of testing numbers when those numbers dropped.

Last month when the number of tests reached a respectable level, Baker lamented the lack of any regional or demographic context, and the ministry then started publishing the testing data in each DHB and across each ethnic group.

But this hasn't been updated since April 18.

Baker has previously lamented poor contact-tracing data, which was later laid bare in an independent audit that revealed the lack of an end-to-end system that could tell us when a case first had symptoms, was tested, had the test result returned, and how long it took to trace and isolate contacts.

Bloomfield says the Ministry aspires to have this end-to-end system, but whether we are there yet remains unclear.

All of this information would ideally be before Cabinet when it makes its big decision on Monday.

But it should also be available for public health experts and members of the public as a matter of course.

That would go some way towards maintaining a high level of public trust and confidence, which is crucial to bringing the public along with whatever decision Ardern and her Cabinet make.