Scientists identify alternative technique to speed up Covid-19 testing

Scientists have identified an alternative amplification technique to detect the genetic material of SARS-CoV-2, that causes Covid-19, which could offer a way to rapidly test large number of people for the disease.

However, the researchers from Heidelberg University in Germany noted that the technique is not as sensitive as quantitative RT-PCR, the current standard method for Covid-19 testing.

Faster and less complicated testing could aid in the rapid isolation of infected people and help to identify and prevent new outbreaks of the disease until a vaccine becomes available, they said.

The researchers noted that quantitative RT-PCR can successfully detect viral RNA but requires expensive machinery and chemical reagents that can sometimes be in short supply.

The standard method also depends on time-consuming temperature cycling steps to amplify enough RNA from a patient sample for detection, resulting in a processing time between three and 24 hours in most clinical laboratories, they said.

In the journal Science Translational Medicine, the researchers propose using a technique called reverse transcription loop-mediated isothermal amplification (RT-LAMP), which can be carried out at a constant temperature using simple equipment and a different set of reagents.

In their tests of RNA isolated from 768 nasopharyngeal swabs from individuals tested for Covid-19, the researchers determined that RT-LAMP was less sensitive than quantitative RT-PCR but could be used to evaluate large groups of people, with an average test processing times of 30 minutes.

They concluded that RT-LAMP works best for identifying people with moderate to high amounts of SARS-CoV-2 virus in their bodies, but is not sensitive enough to identify infection in people with a low viral load -- such as those at the beginning or end of the illness.

The researchers also tested the possibility of using RT-LAMP directly on nasopharyngeal swabs -- without the need for RNA isolation -- but concluded this technique was less sensitive than using isolated RNA.