India assesses Covid-19 sample pooling for tests, says top scientist. How it helps

Updated on Mar 30, 2020 03:15 PM IST
India’s principal scientific adviser Vijay Raghavan answered a series of questions on Twitter on the coronavirus disease, including the methodology used to test for Covid-19.
Health workers conduct a Covid-19 test in Petaling Jaya, Malaysia, on March 30.(AP Photo)
Health workers conduct a Covid-19 test in Petaling Jaya, Malaysia, on March 30.(AP Photo)
Hindustan Times, New Delhi | ByHT Correspondent

India is looking at increasing the capacity of testing for coronavirus disease Covid-19 by pooling of samples. The effort was announced on Twitter by India’s principal scientific adviser Vijay Raghavan.

“Efforts to increase test capacity by the ‘pooling’ of samples are being evaluated. This is not simple and needs the development and testing of optimization algorithms so that one positive in a large pool is not missed, for example,” Raghavan said in one of the tweets he posted after midnight on Sunday. 

So what is pooling of samples?

The idea has been proposed by scientists in Israel where this method is being used. It involves testing of samples in batches to know the presence of Sars-Cov-2 virus. Only in cases where the virus is found in the group of samples will the individual need to go for own test.

The scientists in Israel successfully used 32 or 64 combined sample to test the presence of the virus.

This methodology has been devised to ease the burden on testing centres by reducing the load of testing individual samples, and give results in a faster and efficient manner.

How will this benefit India?

There were just over a million doctors registered with state medical councils in 2017, of which only 80 per cent were estimated to be in active service, according to the government. This means, India has one doctor for every about 1,500 persons; WHO norms suggest that there must be one doctor for every 1,000 persons. In rural India, however, this ratio goes down to as low as one doctor for over 10,000 patients.

India has tested just 35,000 people for coronavirus on Sunday, according to the Indian Council of Medical Research, a minuscule portion given its population size.

Experts have already suggested an all-hands-on-deck approach to strengthen the healthcare workforce. So, pooling of samples is going to help the healthcare experts a lot in the country.

Is pooling of samples an old technique?

Actually, it’s not. Pooling has been used since the Second World War and was even suggested for testing patients with HIV in the 1990s.

Covid-19 is diagnosed with Reverse Transcription Polymerase Chain Reaction (RT-PCR) laboratory technique, which according to US Food and Drug Administration (FDA), is intended to detect the unique genetic sequence of viruses in upper and lower respiratory specimens in sample taken from patients.

“There are new tests being rolled-out, globally, for the presence, or traces of the virus having visited a person. These can be useful as a first-pass, even if they are cruder than the ‘gold-standard’ RT-PCR. Indian labs are developing these kinds of tests too,” Raghavan said on Twitter.

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