Washington: Scientists have developed a new method of testing for COVID-19 that doesn't make use of key reagents but still delivers an accurate result, an advance that may lead to an inexpensive diagnosis technique in developing countries where chemical supplies are in short supply.

The method, described in the journal PLOS Biology, omits the step in the widely used reverse transcription polymerase chain reaction (RT-PCR) test where the scarce reagents are needed, but has an accuracy of 92 per cent, missing only the lowest viral loads.

The researchers, including those from the University of Washington in the US, tested the new method using 215 COVID-19 samples that RT-PCR tests had shown were positive, with a range of viral loads, and 30 that were negative.

They said it correctly identified 92 per cent of the positive samples and 100 per cent of the negatives.

While the positive samples the new test failed to catch had very low levels of the virus, the scientists said ultra-sensitive tests that identify individuals with even the smallest viral loads may not be needed to slow the spread of the disease.

"It was a very positive result," said Jason Botten senior author of the study from the University of Vermont in the US.

"You can go for the perfect test, or you can use the one that's going to pick up the great majority of people and stop transmission," Botten said.

While standard PCR tests have three steps, the version developed by the researchers has only two, the study noted.

"In step 1 of the RT-PCR test, you take the swab with the nasal sample, clip the end and place it in a vial of liquid, or medium. Any virus on the swab will transfer from the swab into the medium," Botten said.

"In step 2, you take a small sample of the virus-containing medium and use chemical reagents, the ones that are often in short supply, to extract the viral RNA. In step 3, you use other chemicals to greatly amplify any viral genetic material that might be there. If virus was present, you'll get a positive signal," he explained.

In the new method, Botten said, a sample of the medium that held the nasal swab is taken directly to the third, amplification step, removing the need for scarce RNA extraction reagents as well as significantly reducing the time, labour and costs required to extract viral RNA from the medium in step 2.

According to the researchers, the test is ideally suited to screening programs, in both developed and developing countries, since it is "inexpensive, takes much less processing time, and reliably identifies those who are likely to spread the disease."

Its low cost and efficiency could extend testing capacity to groups not currently being tested, including the asymptomatic, nursing home residents, essential workers and school children, Botten added.

He said the standard RT-PCR test could be reserved for groups, like health care workers, where close to 100 per cent accuracy is essential.

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New Delhi, Nov 21: Karnataka Chief Minister Siddaramaiah on Thursday launched the Karnataka Milk Federation's (KMF) Nandini brand milk products in the Delhi-NCR market, pricing them marginally lower than competitors to gain a foothold in the region.

The cooperative will retail four cow milk variants, curd, and buttermilk from Friday, with competitive pricing that undercuts established players like Mother Dairy and Amul.

Cow milk will be sold at Rs 56 per litre, full Cream Milk at Rs 67 per litre, Standardised Milk at Rs 61 per litre, Toned Milk at Rs 55 per litre, and curd at Rs 74 per kg.

"We have surplus milk in the state. KMF along with Mandya Milk Union will market surplus milk of 3-4 lakh litres per day in Delhi-NCR," Siddaramaiah told reporters after launching the products.

The federation currently collects 100 lakh litres of milk daily, with local consumption at 60 lakh litres, leaving a surplus of 40 lakh litres for expansion into new markets.

However, the Chief Minister acknowledged the challenges of transporting milk over 2,500 km, which takes 50-54 hours.

There is a need to find new markets for surplus milk and gradually the KMF should be able to sell 5-6 lakh litres per day in Delhi-NCR, he added.

KMF Chairman LBP Bheemanaik assured that milk quality would be maintained during transit.

The federation has already partnered with 40 dealers in the Delhi-NCR region to facilitate sales, he added.

With a robust infrastructure of 26.76 lakh milk producers, 15,737 dairy cooperative societies, and 15 district milk unions, KMF has a turnover of Rs 25,000 crore and exports dairy products to over 25 countries.

State Animal Husbandry Minister K Venkatesh and Agriculture Minister N Cheluvarayaswamy were present at the product launch.