Despite the deluge of numbers shared in the hours of daily Covid-19 press conferences, some numbers remain elusive and the reason why isn’t consistent or clear.

It’s been 74 days since the first case of Covid-19 was announced in New Zealand and while the daily scrutiny of numbers has created a nation of epidemiology hobbyists, answers to some key questions aren’t forthcoming.

Community transmission happened. The public don’t know whether this happened in their neighbourhood, or hundreds of kilometres away.

Hospitals weren’t overwhelmed but finding out how many people have been in hospital has been tricky. People in hospitals with Covid-19 haven’t necessarily been counted as being in hospital. 

Data shared by the Ministry of Health has been tantalisingly vague on key measures. This has drawn criticism from university researchers trying to make sense of risk. Does overseas travel mean someone caught the virus overseas even when there’s an enormous gap between their travel and the date their details were recorded? It’s not clear from what’s in the public domain.

For all the hours of press conferences, the transparency of the Ministry of Health response has been less than crystal clear at times.

At worst there’s a feeling there’s been obfuscation of facts. At best an acknowledgement staff could simply be overwhelmed in a crisis. While some media questions fall through cracks, others are diligently responded to in-depth over evenings and throughout weekends. 

The hospital numbers disconnect

How many people who have Covid-19 are in our hospitals?

Residents of some rest homes with confirmed or probable cases of Covid-19 shifted into hospitals didn’t make the official daily count. They might have been at a hospital, in a hospital bed, eating hospital food, tended to by hospital staff wearing PPE and have a confirmed or probable Covid-19 infection but until they received hospital-level care they weren’t included in official numbers. 

Director-General of Health Ashley Bloomfield explained the relocation of residents from rest home to hospital. 

“It’s not because they need hospital-level care; it’s because the assessment of the clinical staff was that was the most appropriate place where they could get appropriate daily supervision and care.”

Yesterday the official number of people hospitalised with Covid-19 was two. One in Middlemore Hospital and one in North Shore hospital.

Readers contacting Newsroom had expressed concern at the disconnect between the official numbers and the rumours of how many Covid-19 positive patients were in hospital. Was something being covered up or was the ministry hopelessly out of touch?

During the weekend, Newsroom attempted to gather the number of people with Covid-19 in hospital who weren’t included in the hospitalised total. 

Depending on which numbers are right, it’s a case of 8+2=2 or 5+2=2

“There are currently three St Margarets residents at Waitakere and five at North Shore Hospital. As mentioned previously, not all residents are receiving hospital-level care and so are excluded from the daily hospitalisation number,” said a Ministry of Health spokesperson.

On Monday, a Waitematā DHB spokesperson said the ministry’s numbers were incorrect and gave a number of five.

“We have a total of five Covid-positive patients at Waitematā DHB. All are at North Shore Hospital (none at Waitakere Hospital) and this includes three residents from St Margaret’s who tested positive before they transferred into our care due to a shortage of staff at the rest home.”

Whether this is important depends whether you were interested in how many people were so sick they needed hospital-level care, or whether your interest was on the overall levels of strain the hospital system was under.

With the public push to flatten the curve so hospitals avoided being overwhelmed, there’s a case for public interest in the number of infected patients hospitals were hosting. Whether the level of care they were receiving was hospital-level, or residential care level could be seen as splitting hairs.

Whose community did community transmission happen in?

The other mystery has been around community transmission. It was a term bandied about in the early days which has since been modified to the more long-winded “locally acquired cases, unknown source”.

It means a person has been infected and the contact tracers can’t find out where the infection came from. Importantly it can mean the virus is circulating through a community.

If there’s community spread going on in your area, then it’s probably wise to take that slight tickle in your throat seriously and get tested.

Newsroom has attempted to establish the District Health Board (DHB) regions this has occurred in.

“As at 9 May 2020, there are 67 locally acquired cases with unknown source. These numbers are too small at DHB level to be released without breaching the privacy of individuals affected,” said a Ministry of Health spokesperson. 

There are 20 DHBs in New Zealand. The ministry has been reporting on cases daily and lately the numbers of new cases has been two or three. Details of these have been shared in the press conferences and in daily data releases. It’s easy to track down the age range, sex, and DHB of every new case announced.

Newsroom asked for clarification, pointing out details were routinely released even when numbers were low: “I’m not sure I can understand the reasoning here. Can you please explain exactly how releasing the information could breach privacy?”

The ministry response: “Our usual policy on reporting numbers is that we don’t report numbers less than 10.”

Yesterday, as three new confirmed cases, with ages, sex, DHB and travel details were announced, Newsroom again tried to clarify the disconnect between the policy of 10 and the reality of what’s regularly shared.

“The Ministry endeavours to balance the need to release details around cases where there is a public health reason to do so, with the desire to protect the privacy of individuals as much as possible.”

After a request, the ministry did release the numbers of one DHB which had more than 10 cases. 

Southern DHB had 17 cases considered to be community transmission. The most recent of these was April 7, over a month ago.

There are another 50 cases scattered somewhere in New Zealand the public aren’t allowed to know about, according to the ministry, because of privacy reasons. 

Privacy Commissioner John Edwards suggested the query be sent to the Ombudsman for urgent review. While not willing to comment on this particular case until it comes across his desk as part of a formal process, he did share ways to balance privacy with information of public interest.

“There are different approaches to disclosing unit level data, depending on the kind of data you’re talking about. Stats NZ for example uses random rounding with a factor of three, which means they won’t report any figure where the actual number is between zero and three. They will instead report zero or three. I understand Statistics Canada uses random rounding of any statistic where there are fewer than five subjects, that is, they will report anything between zero and five as zero or five.”

Newsroom is seeking an urgent review.

The daily spreadsheet

It’s not just media calling for better information. A spreadsheet published every day by the ministry has been criticised by University of Otago’s Gordon Purdie, Nick Wilson, and Michael Baker.

In a polite blog post, its shortcomings are pointed out. Helpful suggestions are made for an improved format.

The cause of transmission isn’t explicitly included in the data beyond an international travel column which is filled with a yes, no, or is left blank. It’s not clear this is the cause of the case. The date listed against each case is the date when details were entered into the database. This isn’t always the date a person was tested, or the date they received a positive result. 

There’s also been frustration at the age groupings. Older people are lumped into a 70-plus group while others are broken out by decade. Data about symptom onset and recovery are also missing. 

The shortcomings of the database were expressed by Bloomfield on April 19 when he was asked if the ministry knew the average length of time contact tracing would take under Level 2. Bloomfield listed three areas of work under way. 

“Secondly, the system that is being used is not one that’s particularly easy to get information out of. So we’re updating that ability to get information not just out of that system, which is called EpiSurv, but also to be able to link it to our other health databases. So that work is happening apace.”

Tomorrow will be 75 days since New Zealand’s first case and 24 days since Bloomfield said work was happening apace. If EpiSurv and data gathering has been improved, the results are not being shared with the public.

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