CCMB-developed dry swab Covid-19 test kit launched commercially

The speedy process is a simple variation of the RT-PCR method and can help scale up Covid-19 testing

A Covid-19 testing method, developed by the Centre for Cellular and Molecular Biology (CCMB) last year to cut costs and time involved, has now been made available on a commercial scale.

The Hyderabad-based CSIR-CCMB had, in November, come out with a technique that eliminates the sample packing in Viral Transport Medium and also the RNA extraction process.

The speedy process is a simple variation of the RT-PCR method and can help scale up the Covid-19 testing 2-3 fold with no additional resources, CCMB states. The dry swab test method has also received the ICMR approval.

The CCMB, on Wednesday, announced a tie-up with Meril Diagnostics, for scaling up the Dry Swab-based tests across diagnostic labs in the country.

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The Gujarat-based medical devices production company said it is currently equipped to manufacture two crore kits per month. “Each kit suffices for 100 tests. Using these kits, each test will cost between Rs 45-60,” said Sanjeev Bhatt, Vice President, Corporate Strategy, Meril.

However, the method still needs the RT-PCR kit and that cost would be in addition. Sample collection, processing-testing charges by the labs are also separate.

In the conventional RT-PCR testing, nasopharyngeal or oropharyngeal swab samples are collected from the suspected individuals and transported to testing centres, sometimes hundreds of kilometres away.

These swab samples are generally placed in a liquid called Viral Transport Medium (VTM). To avoid leakage, the samples are packed heavily adding to the processing time at the collection and testing centres. Despite such care, there are leakages from samples sometimes, which render those batches untestable and unsafe in handling.

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CCMB researchers found that VTM can be avoided totally. Dry swab technique also does not require the RNA extraction process, and can be directly used for RT-PCR testing with sensitivity and specificity similar to the current gold standard.

“RNA extraction, even with automation, takes four hours for roughly 500 samples. VTM and RNA extraction both add a significant burden on money and time required for mass testing for coronavirus. We believe the dry swab method has the potential of bringing the costs and time of testing by 40-50% in all kinds of settings,” said Dr Rakesh Mishra, advisor, CCMB.

The extraction-free Dry Swab Kit can be used to isolate the viral RNA from dry swab samples. These isolates can then be directly used for RT-PCR.

“Applying this method, one can simply break open the cells by using appropriate buffer solutions and use them for RT-PCR directly. There is no need for separate steps of RNA extraction and purification,” Dr Vinay Nandicoori, director, CSIR-CCMB said.