New Zealand's current Covid-19 case rates are "what we want to see at this stage", an infectious diseases specialist says.
Today, the Government reported 50 new cases of the virus – the lowest number in two weeks – which came in step with the highest ever number of tests in a single day, 4098.
Otago University's Professor David Murdoch said that the positivity rate of tests carried out was tracking at less than 2 per cent.
"So that would indicate that we are testing a good number of people," he said.
"We are in the top eight countries in the world, along with the Iceland, Switzerland, and Norway, in terms of the numbers that we are testing.
"Of course, the question is, are we reaching all of New Zealand? And it's a really important question because the testing stations have been designed to reach everywhere.
"But certainly, the indications are that this is what we want to see at this stage."
Murdoch said there were wider testing measures that could put in place to give more confidence that community transmission wasn't happening around New Zealand.
"This is a really crucial part of the elimination strategy because we need to be confident that it is working and that we're confident the numbers – assuming they continue to go down – stay down."
Expanding testing could involve broadening the case definition for testing, or targeting certain groups of people who were vulnerable.
"There is always talk of testing people without symptoms and it's a little bit of a dangerous area because we don't know the test performance in that area.
"But certainly, a case can be made for testing extra people, just to add extra confidence. It won't be a very efficient way of going about it, because there'll be lots of negatives likely."
Murdoch said the biggest concerns for the seven labs running testing around the country wasn't capacity – which they were operating within – but maintaining the supply chains for imported testing equipment.
"Getting that supply chain for the length of time we need it, that's the major concern at the moment," he said.
"The worst-case scenario is every country in the world could be overwhelmed… we hope we never get to that, but at the moment, we have spare testing capacity, as long as the supply chain is maintained."
Director General of Health Ashley Bloomfield said there were 4098 tests yesterday, the highest number so far, bringing the total to 46,875.
Stock for tests was about 50,000, he said.
Bloomfield said there wasn't enough information about the loss of smell for it to be added as a specific symptom for people to be tested on that symptom alone.
Asked about people waiting up to a week to have test results returned, Bloomfield said people were told about positive results immediately, and he was aware of reports that negative results sometimes took longer than they should have.
"People will be waiting and they'll be anxious while they wait."
He said he had contacted a DHB boss this morning when he found out about a case where the test result took longer than it should have.
Bloomfield said the case definition wasn't designed around community testing, which was part of broader surveillance testing.
Prime Minister Jacinda Ardern said yesterday there was reason to be "quietly confident and cautiously optimistic".
Another good sign was that the number of close contacts that cases were reporting had gone down to two or three people – because people were confined mainly to their homes under alert level 4.