Have you had stealth Covid-19? This new test will tell you

Kiwis will soon have a new way to discover whether they’ve unknowingly had Covid-19, with a simple blood-based test developed by two New Zealand companies.

Rako Science and Pictor today unveiled their new antibody test – dubbed Test2Detect – which they say will give people critical information for their Covid-19 vaccination plans.

There’s also potential for the tests to help shed fresh light on New Zealand’s blurry immunity picture – particularly our hidden proportion of asymptomatic cases – as health officials develop long-awaited national prevalence surveys.

Initially to be made available at Rako’s Auckland CBD and Christchurch locations, the tests are able to detect whether a person’s body generates an immune response from having caught the coronavirus.

This is done by picking up those circulating antibodies that are triggered in response to both the virus’ spike protein (SP) or nucleocapsid protein (NP).

In someone who’s been only vaccinated but not exposed to the virus itself, just the spike protein would be triggered – meaning the test can differentiate immunity from vaccine or viral infection.

The tests are expected to be useful for people keen to regularly check their virus antibody levels – something that may help them guide when to get booster shots.

A blood sample is collected using Rako Science and Pictor's Test2Detect - a simple antibody test that can detect whether someone has had been unknowingly infected with the virus that causes Covid-19. Photo / Jesse Marsters

University of Auckland immunologist Dr Anna Brooks, who serves as a consultant with Auckland-based Pictor, said the test would also be useful for those people experiencing Long Covid symptoms, but who hadn’t had confirmation of infection.

“Timing your test since your infection is important, as NP antibodies wane faster than SP,” she said.

“However, not everyone generates detectable NP antibodies, but it will be worthwhile checking, just in case this helps confirm you’ve had Covid-19.”

International studies indicate asymptomatic transmission may account for four in 10 cases, yet, without a national sero-prevalence survey built on regular blood samples in the community, it’s tough to say how many people have Covid-19 at any one time.

Similarly, it’s hard to calculate how many Kiwis have had Covid-19 at all.

With two waves of the ultra-infectious Omicron having washed over New Zealand – and a third one infecting thousands more people each week – that proportion is likely to be at least two-thirds of the population.

While more than 90 per cent of the population has had at least two doses of the Pfizer vaccine, for many Kiwis, the neutralising antibodies they gained would have significantly waned since their last shot.

Rako Science and Pictor today unveiled their new antibody test – dubbed Test2Detect – which they say will give people critical information for their Covid-19 vaccination plans. Photo / Jesse Marsters

Rising numbers of reinfections – now accounting for at least two in 10 of national cases – were now making our immunity profile even more complex.

Rako Science director Leon Grice told the Herald that, while the tests had obvious benefits for personal health, he saw no reason the tech couldn’t be used at a population level.

The company had been in months-long discussions with the Ministry of Health in regard to national prevalence studies, now not expected to launch until 2023.

While filling in key gaps in surveillance, this would also be useful in comparing our sero-prevalence to countries like Australia, where there’s now good data to show that more than 80 per cent of people have been infected.

The test was the first of its kind developed in New Zealand, and allowed people to order what was a typically expensive lab process at a cheaper price.

“A significant amount of investment has been made to bring this test to the market and our partnership with Rako Science increases accessibility to this important clinical tool for those in remote locations,” Pictor’s chief executive officer Howard Moore said.