Government to test sewage at managed isolation facilities

The country's Crown Research Institute in charge of testing for Covid-19 will begin testing the sewage of managed isolation facilities, Marc Daalder reports

Scientists at ESR, the Crown Research Institute that has led New Zealand's Covid-19 testing response, have plans to test sewage from managed isolation and quarantine facilities for Covid-19.

Sewage testing, which New Zealand is already experienced in when testing for poliovirus, allows countries with active outbreaks to track changes in prevalence of the virus and allows those without outbreaks to monitor for warning signs, ESR research and development manager Dr. Brent Gilpin told Newsroom.

"Wastewater testing offers the potential to identify if the virus is circulating in the community – as the virus causing Covid-19 can be excreted in faeces a few days before people show any symptoms. The use of wastewater to detect the Covid-19 virus provides an opportunity to develop an early-warning monitoring tool designed specifically for New Zealand’s conditions," he said.

ESR first trialled sewage testing for the coronavirus in mid-April, targeting areas with significant outbreaks like Matamata and Wellington. Early tests managed to detect the virus in sewage, proving the system was operational.

Now, that work will continue with the testing of sewage from managed isolation and quarantine facilities housing returnees from overseas.

"ESR hopes to establish sampling of sewage from such a facility as soon as possible and is in discussion with Watercare, hotel management and the Ministry of Health," Gilpin said.

"ESR wants to do this initially to calibrate the sampling and testing against the known positive cases. As part of this ESR would like to establish testing of faeces and saliva from people who test positive, and collect information on their daily activities and health. This will inform the feasibility of expanding this to other facilities or regions."

"Testing everyone presenting to hospital with a runny nose or sore throat is, in our experience, having negative downstream consequences on the delivery of healthcare..."

The early-warning system isn't totally accurate yet, Gilpin said. ESR hopes the testing of managed isolation facilities and further trials will ensure the system doesn't produce false negatives.

"We need to be really confident that if the test results don’t show any SARS-CoV-2, that there really aren’t any infected people in the community. When, where and how much sewage to test, to be able to detect a very low number of cases, are key questions that we need to understand better," he said.

The development of the early-warning system comes as doctors around the country warn the Government's widespread Covid-19 testing has put strain on staff and resources.

"Testing everyone presenting to hospital with a runny nose or sore throat is, in our experience, having negative downstream consequences on the delivery of healthcare," Canterbury DHB's interim head of infection prevention and control Joshua Freeman said.

"I agree with community testing  - however there is a risk that the numbers of tests required to test all of these with any of these listed symptoms will mean that health services are diverting staff and resources to testing and away from usual care," Lynn McBain, the head of the University of Otago (Wellington) department of primary health and general practice, said.

McBain proposed consideration of alternative models of community testing to alleviate the burden on primary practitioners and overwhelmed CBACs. The sewage testing could do just that.

While Director-General of Health Ashley Bloomfield has insisted testing will remain accessible for anyone with any symptoms, he agreed sewage testing could complement the effort.

"It's a very useful supplement," he said.

Bloomfield said the Ministry of Health would shortly be releasing a surveillance plan, which would include widespread community testing, sewage testing and symptom monitoring efforts.

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