Saturday, November 27

ESR Says Sewage Tests Tool In Kit To Detect Covid-19

The Institute for Environmental Science and Research (ESR) has developed a number of new techniques to use in wastewater testing in an attempt to detect Covid-19.

The machine sorts Covid-19 positive samples for genome testing.

A machine sorts Covid-19 positive samples for genome testing.
Photo: RNZ / Dom Thomas

Public health professor Philip Hill yesterday raised concerns about the tests, saying there were questions about their sensitivity and their ability to distinguish between viable and non-viable viruses.

He said the sensitivity of wastewater testing is not absolutely clear.

“You cannot distinguish a basically unviable virus from a viable virus, in other words, when you are no longer infectious and you are still getting rid of some viral particles that have parts of the genome that are still detectable, then you will still be positive in the waters. residuals “.

ESR chief scientist Brett Cowan agreed, saying that people can continue to shed the virus for some time, even weeks after being infectious, but the amount of virus they are shedding generally decreases during this time.

But he said the sensitivity of wastewater testing is now much better understood.

“We know that if we do the test outside of Jet Park, Auckland’s quarantine facility, the water is always positive, but that’s a very easy case. If we add 100,000 people to that sewage stream and do the test at the end of that current, we know that maybe if we have five or six positive people in that basin, we will probably detect it. “

He said that sewage testing is just one tool in the kit, and right now the most important tool is contact tracing.

Cowan said the sewage tests provide a wide image similar to that taken by a satellite.

“We can see a lot of New Zealand, up to 80 percent, but we see it at slightly lower resolution.”

Cowan said testing tends to be done at the city level and an unexpected positive result would require further investigation.

First, he said they would test more frequently, perhaps moving on to daily testing.

“The second thing we would do is if a particular city had four main pipes going into that treatment station, we would test them individually. If we found one of them to be positive, we could go up the pipeline system to get more and more specific. . “

Cowan said the amount of viruses shed by people with Covid-19 is quite variable, with some people shedding a few thousand virus particles while others shed billions.

Cowan said ESR scientists have been looking for viruses like norovirus in wastewater for a few years.

“What is new however is the focus on Covid, there are a number of new techniques and approaches that we are using for Covid that have allowed us to improve the performance of these tests.”


This is an official COVID-19 ALERT.

All New Zealand You are now at Covid-19 Alert Level 4.

The alert level will be reviewed after 3 days for all areas EXCEPT Auckland and the Coromandel Peninsula, which will likely remain at level 4 for an initial period of 7 days.

A community case of Covid-19 has been identified.

Stay at home whenever possible and follow level 4 alert guidelines. This will stop the spread of Covid-19 and SAVE LIVES.

All are asked to:

Wear a mask and keep a distance of 2 meters from others when you leave your house.

If you are sick, call your doctor or Healthline on 0800 358 5453 for advice on getting tested.

Keep scanning QR codes every time you leave your home.

Practice good hygiene: wash your hands often.

Services that include supermarkets, pharmacies, clinics and gas stations will remain open at alert level 4. Face covers are mandatory for all people, both employees and customers, in companies and services that operate at alert level 4 that involve contact with the client.

For more information on Alert Level 4, go to [the government website]


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Kia Kaha – Stay strong

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