Unknowns still to virus spread

‘Test, test, test,’’ Prime Minister Jacinda Ardern said a week ago. And since then more than 20,000 tests have been run and the number of coronavirus cases has almost doubled.

Nearly two weeks into a monthlong lockdown and experts say New Zealand is tracking well. Testing of symptomatic Covid-19 cases appears to be in full swing, the number of new cases appears to be decreasing, and clusters of the virus have been rooted out.

Dr Ashley Bloomfield, the director-general of health, said yesterday he was ‘‘increasingly confident’’ that the number of coronavirus cases were trending down, and the data indicated there may not have been much community transmission happening when the country entered lockdown. However, experts tracking the coronavirus response say there remain some large unknowns that need to be answered before New Zealand can exit the lockdown safely.

Test, test, test

Professor Michael Baker, an Otago University epidemiologist who has been advising the Government on its pandemic response, was not concerned about the possible testing opportunities missed and said it was right to focus on people with acute Covid-19 symptoms.

‘‘It sounds like there are not many positives coming through, which is good news, but you have to have that other bit of information now, which is, what’s the distribution of testing?’’

He said a broader range of people needed to be checked through surveillance testing – reaching into the community to find transmission of the virus – and he provided three hypothetical examples why.

‘‘If there were cases in the Samoan community in South Auckland, and remaining affecting young Samoan people, the virus could circulate to several generations before it’s detected if those people were not turning up at clinic.

‘‘Or, if it was circulating amongst young people in the North Shore of Auckland, some of whom have recently been, in the last couple of months, on a trip to Hong Kong ... and the virus has just continued to circulate in that group.

‘‘Or, on the West Coast, where the woman unfortunately turned up in hospital and died quite quickly, I haven’t seen explanation for how she got infected but perhaps there is some circulating virus linked to tourists who came through two months ago.’’

Baker, along with colleagues, published a paper detailing four surveillance testing methods – the first being the current testing regime – which would help confirm the virus had been eliminated.

He said focus should now be on testing of people who ‘‘are not particularly ill’’ in communities that are ‘‘hotspots’’ for the virus, or in deprived areas with crowded homes that might not be accessing testing stations.

Another method could be testing people with a higher risk of exposure to the illness: contacts of cases without symptoms, healthcare workers, and other essential workers such as supermarket staffers.

The fourth method would be to either test sewerage, or conduct widespread community testing, to ensure a region was free of coronavirus.

Both Health Minister David Clark and Bloomfield, speaking at a parliamentary select committee yesterday, said the Government was working on a plan for targeted surveillance testing.

More details were expected to come within days.

The missing 16 per cent

For the past week, nearly 20 per cent of coronavirus cases have been under investigation as health officials track the person’s movements to determine where the virus was picked up — a vital task in cornering community spread.

But this contact tracing, currently done manually and largely over the phone, will not be enough once the lockdown lifts, Sir Peter Gluckman said. ‘‘We need fast and effective contact tracing. That is the guts of maintaining our security of low pandemic risk after the lockdown is completed.’’

A former science adviser to the prime minister, Gluckman said technological solutions – various phone apps which tracked other phones within proximity – had worked in Singapore and South Korea to quickly determine who a Covid-19 case had come into contact with.

‘‘People don’t want to be yoyoing in and out of lockdown, or high levels versus low levels. People have made large sacrifices ... We owe it to all of them and to our safety to have all the weapons at our hands that will keep us safe,’’ he said.

Bloomfield has said there were now 190 staff working on manual contact tracing, using a system now linked to the National Health Index – speeding up the process.

‘‘We need fast and effective contact tracing. ’’

Sir Peter Gluckman Scientist