Is this the future of Covid-19 testing?

Simplified testing technique could be of particular interest to countries and regions with limited resources, writes Harry Cockburn

Bjorn Reinius, principal investigator of the study (centre) with co-first authors Ioanna Smyrlaki (right) and Anders Ekman (Stefan Zimmerman)

A team of researchers in Sweden say they have developed a new method for fast, cheap and accurate Covid-19 testing that could be rolled out quickly.

Scientists at the Karolinska Institute in Stockholm said their method circumvents a complicated part of other testing methods, thereby speeding up the process, and requiring fewer expensive chemicals.

Existing tests for Covid-19 infection depend on the detection of viral RNA taken from patients by nasal or throat swabs. From these samples the RNA molecules must then be extracted and purified.

This RNA purification process can result in a major bottleneck for the testing process because it requires “a great deal of equipment and logistics as well as expensive chemical compounds”, the Swedish team said.

The new technique removes the RNA-extraction procedure. Instead the patient samples are taken, then inactivated by means of heating, which renders the virus particles no longer infectious.

The first version of the scientific research was published on the preprint server medRxiv, where it was read more than 15,000 times even before it was then peer-reviewed by other experts in the field and officially published in Nature Communications.

In this state it can pass straight to the diagnostic reaction that detects the presence of the virus.

According to the researchers, the most important aspects of their method's success are the virus inactivation procedure, and a new formulation of the solution used to collect and transport the sample material taken from the patients.

“By replacing the collection buffer with simple and inexpensive buffer formulations, we can enable viral detection with high sensitivity directly from the original clinical sample, without any intermediate steps,” said Dr Bjorn Reinius, research leader at the Department of Medical Biochemistry and Biophysics at Karolinska Institute.

The potential for cheap and rapid roll-out of the tests means it could be particularly useful in countries and regions with limited resources, the team said.“We started working on the issue of developing a readily available testing method as soon as we saw the developments in Asia and southern Europe, and before the situation reached crisis point in Sweden,” said Dr Reinius.“Our method was effectively finished already by the end of April, and we then made all the data freely available online.”The early data, which at that stage was not peer-reviewed, sparked significant interest among institutions and research groups around the world.

“Thanks to the low cost and the simplicity of the method, it becomes a particularly attractive option at sites and in situations with limited resources but a pressing need to test for Covid-19,” Dr Reinius said.

“I would certainly like to see this test used in Sweden too, for example for cheap periodic testing of asymptomatic people to eliminate the spread of infection.”

The possibility of a rapid roll-out of simpler tests comes as the UK is facing demand for tests at four times the current capacity, while 90 per cent of tests being done are failing to hit the 24-hour turnaround target.

Furthermore, the NHS test-and-trace programme is grappling with looming shortages of the chemicals and machines required for the existing tests.

Prime minister Boris Johnson has pledged enough capacity to test 500,000 people a day by the end of October, but production is running two or three weeks behind schedule.

The research is published in the journal Nature Communications.