Coronavirus: Expert confident latest cluster of COVID-19 cases can be contained

An infectious diseases expert says while the latest string of COVID-19 cases in Auckland is "a concern", locals should have confidence the outbreak can be contained.

There have been 11 cases discovered so far in the cluster, centred on Papatoetoe High School. There's concern however just two days after getting back to level 1 the city could go back to level 3 restrictions, after it emerged one of those infected worked two shifts at Kmart in Botany, on Friday and Saturday. 

University of Otago expert David Murdoch told The AM Show on Wednesday the current situation "ranks" with previous outbreaks in Auckland.

"Any new cases are a concern. We really need to be doing what we've been doing - the contact-tracing is underway, it still looks connected which is good but obviously extra cases, extra places to do testing, there's obviously anxiety around that." 

In the past, when cases have clear lines of transmission we haven't had to move alert levels - it's when cases pop up with no obvious source of infection, such as a week-and-a-half ago and in August last year, that alert levels typically move up. 

All students at Papatoetoe High are being urged to get retested.

"The extra testing is important because what happens is sometimes if you test people very early on, they can be negative," said Dr Murdoch. "It is important to do this again, given the situation we're in."

The typical incubation period for SARS-CoV-2, the virus which causes COVID-19, is about six days - but that's only an average, hence the 14-day isolation period people are required to undergo if they're a suspected case or coming into the country. 

There have been cases of incubation periods even longer than that - around 1 percent of cases, according to research. 

If there is a wider outbreak, Dr Murdoch says at least we know what to do - New Zealand's zero-tolerance for unchecked community transmission has seen it record one of the lowest death tolls in the world (in fact, New Zealand was actually one of just a handful of countries to record a drop in deaths in 2020, according to excess mortality figures). 

"We have been in this before, we're likely to be in it again. We know it works, and we know this is what we have to do going forward while we get the vaccine rolled out and the world changes in response. It is a nuisance, but it is something we just have to do."

Director-General of Health Ashley Bloomfield told The AM Show all the cases had been linked genomically, and there was no need - at this stage - to raise the alert level.