Covid 19 coronavirus: 3 ways New Zealand could try harder and smarter

New Zealand labs run a staggering number of Covid-19 tests every day.

With our total count approaching the 1 million mark, labs across the country are processing just over 5,000 samples daily.

As the Auckland outbreak showed, it could quickly escalate to 20,000, but it was grueling and painstaking work.

And, contrary to popular belief, it was not automated, with a series of manual steps that laboratory technicians had to repeat up to thousands of times a day.

“The risks of overuse and occupational burnout among laboratory scientists are very real,” said Dr. Joshua Freeman, clinical director of microbiology and virology for the Canterbury District Board of Health.

“This threatens the sustainability of our public health response. For this reason, laboratories are working hard to eliminate the manual steps of processing and analyzing Covid samples.”

New Zealand’s standard test method for Covid-19 remained what is called the polymerase chain reaction or PCR.

That involved looking for the genes of the virus in a sample taken from the person being tested, usually with a swab from the nose or throat that kiwis are now familiar with.

Could we do it another way?

Rapid antigen tests

Last week, the World Health Organization announced an initiative to make so-called rapid antigen tests available to low- and middle-income countries.

These tests detect specific proteins (antigens) on the surface of the virus that causes Covid-19.

They are considered as attractive as they are easy to use, may not need to be performed in a laboratory, and provide results in as little as 15 to 30 minutes.

In contrast, PCR tests require technical expertise, must be carried out in laboratories, and typically take up to 24 hours to provide results.

Why have these tests not been implemented here and elsewhere?

“One of the main reasons has been concerns about the accuracy of these tests and, until recently, there was little data on their performance,” explained Professor David Murdoch, a clinical microbiologist and infectious disease physician at the University of Otago.

“We now know that rapid antigen tests are less sensitive than PCR for detecting Covid-19 cases and may not detect fewer than 20 percent of cases.”

In other words, he said, they could produce a relatively high proportion of false negative results.

That meant scientists had to weigh the benefits of ease of use and quick response times, against the risk of more cases being lost.

“There is a valid argument that people who have a positive rapid antigen test are more likely to have high levels of the virus and are more likely to be infectious to others,” he said.

“However, it is not yet clear how certain we can be that a person with a negative rapid antigen test is not infectious.”

Saliva and serology tests

ESR scientists have been exploring the potential of saliva tests, which can be more sensitive, effective and less invasive than nasal swabs.

It has already been suggested that our border workers could be excellent candidates for using rapid and minimally invasive techniques, such as the SalviaDirect method developed by researchers at Yale University and recently approved by the US FDA.

Border workers can submit a saliva sample every day, or every few days, along with routine temperature checks and health questionnaires.

But Freeman did not consider saliva testing to be currently viable for laboratory processing, as the samples required additional manual steps to homogenize and liquefy the sample.

Even after homogenization, big unanswered questions remained about whether large volumes of samples could be reliably processed on available automated instruments.

“Therefore, when comparing the merits of saliva with nasopharyngeal swabs, the implications for our workforce of laboratory scientists and realism about what can be achieved in practice in the laboratory setting must be considered,” he said. Freeman.

“Saliva can certainly have a niche role as an alternative to nasopharyngeal swabs, but a lot more work is required before we know whether the high-volume saliva test is a realistic option.”

Serological tests, meanwhile, were blood tests that could show whether a person may have ever been infected without knowing it, revealing chains hidden in outbreaks with mysterious sources.

They also had the potential to identify those who were infected within a few minutes, allowing them to isolate themselves and avoid infecting others.

“These are becoming more important as the pandemic progresses and we are looking to find those people who have had the disease but didn’t know they were sick,” ESR Executive Director Peter Lennox told the Herald last month.

“We are waiting for the ethics around a study in the area of ​​serology, so keep your eyes peeled for this.”

Waste water testing

Another area ESR is exploring further was the possibility of sewage stations being used for Covid-19 surveillance at the community level.

The approach, called wastewater-based epidemiology, has already been used in New Zealand to study other viruses and even illegal drug use.

Recent studies have suggested that live traces of the virus can be isolated from the feces and urine of infected people and can sometimes survive for up to several days after leaving the body.

The concept was being pushed by many prominent Kiwi scientists, including Professor Neil Gemmell of the University of Otago, who is part of a group led by ESR that just awarded $ 1.6 million to begin research.

“The main message is that the research is progressing, but the data from the sample collection is not yet actionable,” Lennox said.

“The overall long-term goal is to have robust and reliable tools for wastewater detection that can be used to identify any unrecognized Covid-19 infections in New Zealand.

But before that could be done, a proper methodology needed to be developed, and sewage samples from Auckland and elsewhere were recently collected for analysis.