Covid-19 coronavirus: Why the counting of Covid deaths is changing

The way we analyse how many people in New Zealand have died from or with Covid-19 is changing, becoming more accurate and informative.

Top health officials say it will better encapsulate the toll the virus has taken on our communities, while also giving us a more useful tool to contrast New Zealand's management of Covid-19 against comparable countries.

A health expert has welcomed the change, but also warned the upgrade may still underestimate the number of Kiwi lives Covid has claimed.

However, a marketing expert says the more transparent reporting system could boost compliance in measures employed to fight transmission, measures considered crucial with six weeks still left of winter.

What has changed?

In the past, deaths associated to Covid-19 have been reported in a quite basic manner in that anyone who died within 28 days of having the virus was considered a 'Covid-death'.

This often came with the proviso that the "underlying cause of death may have been unrelated to Covid-19", as per the Ministry of Health's website currently.

As of Friday, Covid deaths will now be reported with a focus on those people deemed to have died with Covid-19 as an underlying or contributing factor.

It would also specify those deaths that were still under investigation.

The numbers were determined by fast-tracking all deaths with an associated positive test report to the Ministry's clinical mortality coding team to determine whether the infection was the underlying cause of the death, contributed to the death, or was unrelated to the death.

Yesterday, New Zealand had registered almost 1900 deaths (1870) of people under the old classification.

The Public Health Agency's deputy director-general Dr Andrew Old. Photo / Mark Mitchell

Today, the Ministry of Health's public health agency deputy director Dr Andrew Old said the true number of Kiwis whose death was due to or contributed to by Covid-19 was 1252.

Old characterised the new system as a better measure of Covid's burden on society and was an approach consistent to that of the United Kingdom, Australia and the United States.

Through that consistency, it had been established New Zealand's cumulative mortality rate was much lower than those countries.

The United Kingdom's cumulative rate was 2648 deaths per million of population. In the US, it was 3057.

Had New Zealand had similar rate, up to 15,000 deaths could have been recorded.

"Whether we're counting deaths from or with Covid, New Zealand has a lower cumulative Covid mortality rate than many other counties, due to our success early on in the pandemic," Old said.

Director General of Health Dr Ashley Bloomfield and the Public Health Agency's deputy director general Dr Andrew Old. Photo / Mark Mitchell

Old estimated the infection either caused or in some way contributed to a person's death in two-thirds to three-quarters of cases.

He reinforced the change in reporting was not as a result of a deficit of care for those with the virus, but instead at the request of the World Health Organisation.

Death data still likely to be an underestimate

University of Otago epidemiologist Professor Michael Baker welcomed the move, saying it was a useful upgrade.

"All health agencies and researchers want health statistics that are valid, i.e. that measure what they intend to measure.

"This change will therefore increase the confidence we have that deaths attributed to Covid-19 are valid."

Otago University epidemiologist Professor Michael Baker. Photo / Supplied

However, he warned even an updated reported system would still undercount the number of deaths caused by Covid-19, as evidenced by other illnesses.

"We know that deaths from other infections such as influenza have always been hugely underestimated.

"Only about five per cent of deaths linked to influenza have this infection recorded as the cause of death.

"This problem is partly because of the way that mortality reporting focused on the underlying cause of death, so tends to default to any major chronic illnesses that a patient had, rather than acute infections that contributed to their death at that time."

Reporting shift could convince anti-vaxxers and boost overall compliance

Marketing expert Dr Bodo Lang believes a clearer and more informative reporting system could help shift anti-vax sentiment in New Zealand communities.

Separate to the health benefits, Lang - from University of Auckland's Business School - said it could convince those less-inclined to follow the Government's pandemic control measures to take them seriously.

"Having this new classification will also be useful to address one of the criticisms from anti vaxxers and Covid doubters: how many deaths are really caused by Covid?

"The evidence will now be clearer on this, possibly resulting in a reappraisal of Covid's seriousness by those who were least likely to follow Covid guidelines."

People are being urged to RAT test and mask up as the second Omicron wave continues. Photo / NZME

Director general of health Dr Ashley Bloomfield again reiterated the importance of mask-wearing and rapid antigen testing, a message echoed by his colleagues as New Zealand experiences its second Omicron wave.

Lang said the improvement of traditionally "opaque" Covid-death reporting could shore up compliance in those measures.

However, he also noted the opposite could occur if new data found Covid had been largely unrelated to many of the previously linked deaths.