Home / Science / Health /  To ramp up COVID-19 testing, ICMR approves dry swab-direct RT-PCR method. How it works

The Indian Council of Medical Research (ICMR) has approved a dry swab-direct RT-PCR testing method for the COVID-19 virus developed by CSIR-Centre for Cellular and Molecular Biology (CCMB). "This method developed by CSIR-CCMB is a simple variation of the existing gold standard RT-PCR method," the ministry of science and technology said in a statement.

The dry swab-direct RT-PCR testing method is aimed at scaling up the testing by two to three fold with no new investment of resources, the ministry said. Considering its lesser cost and quick turn-around time, ICMR has now issued an advisory for the use of CSIR-CCMB dry swab method.

CSIR-CCMB has been testing samples for coronavirus since April 2020. After working closely with the healthcare workers of Telangana, it identified some of the key issues that slow the testing process. To make the testing process faster and simpler, the researchers developed the dry swab RNA-extraction free testing method for the COVID-19 virus.

In the conventional testing method, nasopharyngeal or oropharyngeal swab samples collected by sample collection centres are transported to testing centres, sometimes even hundreds of kilometres away. The samples are generally placed in a liquid called Viral Transport Medium (VTM). To avoid leakage, they are packed heavily that adds on to sample processing times at both the sample collection and testing centres.

"The dry swab-Direct RT-PCR method involves collecting and transporting the nasal swab in dry state which makes the transportation and handling of the samples easy and less prone to spillage and spread of infection," the ministry said in a statement.

In dry swab-direct RT-PCR testing, the step of RNA isolation from the sample is omitted. It involves processing of the sample followed by direct RT-PCR using the kit recommended by ICMR. "Omitting the step of RNA isolation offers a huge benefit over the conventional method, as the RNA isolation is a major bottleneck in terms of time, cost and trained manpower," the official statement mentioend.

"Dry-swab direct RT-PCR method is cost effective, easy to implement with no requirement of new kits and existing manpower can perform this with no additional training and hence could make a significant contribution to ramping up the testing capacity in the country quickly," explained Dr Shekhar C Mande, DG-CSIR.

"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," said Rakesh Mishra, Director, CCMB.

"We believe dry swab-Direct RT-PCR method's merit holds for all kinds of settings and has the potential of bringing down the costs and time of testing by 40-50%. It is a game changing technology as with the existing infrastructure, the throughput of COVID-19 screening can be enhanced several fold with immediate effect while, at the same time, making the whole process safer," Mishra said.

The modified method of CSIR-CCMB has also been independently corroborated by premier institutes and hospitals including Centre for DNA Fingerprinting and Diagnostics (CDFD), IISER-Berhapmur, CSIR-NEERI, GMCH-Nagpur, Genepath based in Pune, IGGMSH and MAFSU, Nagpur and Apollo Hospitals, Hyderabad.

Further, the dry-swab direct RT-PCR method has been published in peer reviewed journal by CSIR-CCMB and by other scientific groups in several prestigious scientific journals across the world.

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