NZ ‘elimination day’ already reached - expert

New Zealand could officially claim today as Covid-19 ‘‘elimination day’’ but health officials have backed away from that idea.

However, leading epidemiologist Michael Baker says the ‘‘countdown’’ was not correct because the country had already officially reached elimination last Monday when the county moved into level 1 and there were coincidentally no active cases.

He is urging the Ministry of Health to release further data to prove this.

Yesterday marked 23 days since New Zealand recorded its last case of Covid-19 but just when the Government will deem the virus ‘‘eliminated’’ from the community has become contentious.

And it looks unlikely it will make that declaration.

Elimination is defined as the absence of a disease at a national or regional level. Eradication refers to its global extinction.

To claim elimination of Covid19, health officials have said they want to be sure two full cycles of the virus’s transmission – 28 days – have passed since the last case of community transmission left selfisolation.

But University of Otago Professor of Public Health Baker said it should be 28 days from when the last case of community transmission went into isolation, and we’re well past that, he said.

He urged the Ministry of Health to release its data showing the last locally acquired case was put into isolation and were no longer a source of other cases.

‘‘Based on some accounts I have heard and reference dates from the ministry, it pretty much coincided with last weekend. By the time Cabinet met on Monday, it was a pretty reasonable time to say elimination has been achieved.’’

There had been a focus on active cases, but the thing that was most important was the likelihood

of having undetected cases in New Zealand, he said.

‘‘Once you get to 28 days since the last infectious person was put into isolation, then you have a 95 per cent chance of elimination.’’

According to modelling by the University of Otago, which lined up with Te Pu¯ naha Matatin research centre in Auckland, there was now a very likely (well above a 95 per cent chance) New Zealand had completely eliminated the virus, Baker said.

Cabinet would have used this modelling when making its decision last week, he said.

There was a need for the Ministry of Health to improve the data it presented on its website, so the country could backtrack its progress to elimination – a date Baker said the country reached ‘‘with a reasonable degree of certainty’’ on Monday, June 8.

The country needed a point for reference and something the ministry could be ‘‘celebrating,’’ he said.

This was a problem he had raised repeatedly with the ministry.

‘‘I have found it frustrating that this date has not been put up for all New Zealanders to see.

‘‘This is a critical date for New Zealanders, so I think it is something that should feature on the ministry website to say, ‘this is the last date that a person got infected in New Zealand /locally acquired case was put into isolation’, therefore the clock started ticking from there.’’

This would exclude people who came from overseas and were found to have the virus but were in quarantine.

The fact Cabinet and its advisers concluded the country could move to level 1 immediately was a very strong statement that in their view the virus was eliminated, he said. ‘‘It all added up last Monday. I think that is the date we should use.’’

Politicians got a bit nervous about having a definition of elimination and may feel that it might set them up to fail, he said.

‘‘By the time Cabinet met on Monday, it was a pretty reasonable time to say elimination has been achieved.’’ Professor Michael Baker