New Covid-19 test could give results in under an hour - but it's yet to be approved

Researchers say they've developed a low-cost swab test that can diagnose Covid-19 infections in about 45 minutes.

The CRISPR-based test – which uses gene-targeting technology and requires no specialised equipment – could help relieve testing backlogs in the United States as Covid-19 continues to spread, the scientists said.

The US Food and Drug Administration has not approved the test, but clinical assessments are being conducted in an effort to fast-track approval. The test is described in a paper published on 16 April in the journal Nature Biotechnology.

"The introduction and availability of CRISPR technology will accelerate deployment of the next generation of tests to diagnose Covid-19 infection," co-lead developer Dr Charles Chiu said in a University of California, San Francisco news release. He is a professor of laboratory medicine at the university.

Easy to interpret

The new test – dubbed SARS-CoV-2 DETECTR – is among the first to use CRISPR gene-targeting technology to test for the presence of the novel coronavirus.

CRISPR can be modified to target any genetic sequence, so test developers "programmed" it to zero in on two sequences in the genome of SARS-CoV-2, which causes Covid-19.

One sequence is common to all SARS-like coronaviruses, while the other is unique to SARS-CoV-2. Checking for both sequences ensures that the new test can distinguish between SARS-CoV-2 and closely related viruses, Chiu and his team explained.

Like other tests, this one can detect coronavirus in samples from respiratory swabs from patients. It provides results in about 45 minutes, compared with roughly four hours for widely used tests based on polymerase chain reaction (PCR) techniques.

The researchers said that another advantage of the new test is that it can be performed in virtually any lab, using off-the-shelf chemical agents and common equipment. PCR-based tests require specialised equipment, limiting them to well-equipped diagnostic labs.

Field testing

The new test is also easy to interpret. Much like a store-bought pregnancy test, dark lines appear on test strips to indicate the presence of coronavirus genes.

While the new test is slightly less sensitive than PCR-based tests, researchers said that's unlikely to have much impact in diagnosis because infected patients typically have high viral loads.

As they work to validate the new test for FDA approval, researchers are making tweaks so that it can be used in field testing at locations such as airports, schools and small clinics.

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