Covid-19 testing of the wider population is on the cards as World Health Organisation research shows people are most contagious within their first few days of being infected

Director-General of Health Ashley Bloomfield says Covid-19 carriers are highly infectious when they show few signs of carrying the virus.

People were most infectious just before or as they first developed symptoms of Covid-19, according to the latest World Health Organisation situation update, Bloomfield said.

He said even where people didn’t show symptoms, the virus could still only be spread through droplets or contaminated surfaces.

“The important thing here is that whatever the transmission, whether it’s symptomatic, pre-symptomatic or indeed if possible, asymptomatic, the same precautions will protect people,” Bloomfield said.

“Better physical distancing. Not going out if you are unwell and putting others at risk. Cough and sneeze etiquette and, very importantly, meticulous hand hygiene,” he said.

Bloomfield said there had been no documented cases of “truly asymptomatic” transmission. 

Once exposed to the virus, a person took between five and six days to develop symptoms, he said. People were most infectious within one to three days of developing symptoms. 

Bloomfield said there were now 868 confirmed cases of Covid-19 across the country. 

Seventy-one new cases were added to that list today. Of those, 49 were new confirmed cases and 22 were probable cases. 

Clusters of cases had been detected in Napier, Wellington, Hamilton, Auckland, Bluff, Matamata and Waitakere. This was where 10 or more people had been infected from one source.

The largest cluster was based around Marist School in Auckland, which had 59 cases of infection.

There were now more than 1 million cases of Covid-19 worldwide. 


Bloomfield said he wasn’t aware of reported plans that shipping containers could be used to add ICU capacity.

However, he noted the country had a number of other options it would go to first before shipping containers were brought in.

Hospitals had freed up space thanks to the halting of all elective surgeries, he said.

Bloomfield said they also had the option of converting hospital office space to ICU units.

“For example, at Hutt Valley Hospital they’ve opened up what was the old ICU – it had been used for office space for several years – to become a spillover for additional ICU capacity if needed,” Bloomfield said.

“We also have our private hospital facilities that we can call on. They would definitely be where we would go first,” he said.


Bloomfield defended the country’s rate of Covid-19 testing and signalled “population testing” could be on the cards at a later date.

A seven-day rolling average of tests was sitting at just over 2000 per day, he said.

The total number of lab tests to date was 29,485, with a high of 3446 tests processed yesterday.

New Zealand also had the capacity to do over 5400 tests each day, he said.

“The more testing we do, the better our picture will be of the extent of infection,” Bloomfield said.

“That would also be the point of doing some more population-wide testing as part of our surveillance to determine what degree of asymptomatic infection we might have,” Bloomfield said. 

He said the country was leading the world in terms of the amount of testing it did per capita. 

Bloomfield wanted there to be enough capacity for both diagnosis of cases and “surveillance” to find new cases within the wider population.

That surveillance would help decide how and when the country would need to move between levels. 

“Two weeks ago, we didn’t need to test as much because there wasn’t as much infection in the country and there weren’t as many contacts to test,” Bloomfield said.

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