Coronavirus / ICMR plans to scale up antigen-based Covid-19 testing

New Delhi: The government is planning to expand the use of rapid antigen-based Covid-19 tests and the country’s top biomedical research body has advised states to use the easy-to-use method to compliment the more rigorous RT-PCR test to detect the coronavirus as infections surge across the country.

A senior official of the Indian Council of Medical Research (ICMR) said rapid antigen-based tests can help to quickly determine an ongoing infection. “This is why it is a good tool that can be used for diagnosis of Covid-19 along with the RT-PCR testing. RT-PCR, while a gold standard in diagnosing Covid-19, needs a proper biosafety level 2 lab for analysis,” said the official on condition of anonymity.

“Antigen based test is a rapid point-of-care test that can be done on the spot without posing a biosafety hazard as it doesn’t deal with analyisng a live virus,” added the official.

These tests detect the presence of a foreign substance in a person’s oral or nasal swab that triggers the production of antibodies, and, therefore, can find infections. But these are non-confirmatory tests. This means that those who test positive through rapid antigen detection tests are considered “truly positive” for Covid-19 but those who test negative must go for an RT-PCR test for re-confirmation.

RT-PCR, or reverse transcription polymerase chain reaction, tests for the genetic material of the Sars-Cov-2 virus. But RT-PCR testing is limited in terms of widespread availability because of the need for a specialized lab for analysis, and it takes about five hours to get results .

Delhi was the first state to roll out antigen-based testing as Covid-19 cases soared in the past two weeks, making it imperative to conduct large-scale quick testing to trace, treat and isolate the infected individuals. ICMR provided 50,000 kits to the Delhi government, and has asked other states to start antigen-based testing.Uttar Pradesh has started the tests.

On Sunday, the sole approved manufactuer of the antigen tests, South Korean SD Biosensor, said daily production had exceeded 200,000. The ICMR and the All India Institute of Medical Sciences, Delhi, validated the Standard Q COVID-19 Ag detection kit by SD Biosensor about two weeks ago.

“We are already producing about two lakh kits in a day, and even started supplying to eligible hospitals,” said CS Bedi, medical advisor, SD Biosensor.

A section of private players complained of lack of availability of the antigen kits.“There is just one company that is approved; we would need more if they want widespread testing,” said a representative of a private lab who did not want to be identified.

Bedi, however, said there was no shortage of testing kits. “We only sell to NABH [National Accreditation Board for Hospitals & Healthcare Providers]and NABL [National Accreditation Board for Testing and Calibration Laboratories]approved hospital and standalone labs as that is mandatory requirement of the government. We are guided by the government directive, and are being extremely careful to not sell the product to someone who may sell it further to people who are not eligible to use it,” said Bedi.

On June 25, the ICMR released a document where it detailed the need for rapid antigen tests to massively scale up testing capacity as the number of Covid-19 cases rise and lockdown restrictions are gradually relaxed.

“As India is lifting lockdowns in various parts of the country in a phased manner, it is expected to see an upsurge in cases of COVID-19 due to increased transmission of SARS-CoV-2 virus. In view of this, it is important to scale up testing capacity to the maximum possible levels,” the document said.

“The gold standard RT-PCR diagnostic test for COVID-19 has limitations in terms of widespread availability. In view of this, there is urgent requirement of reliable and convenient rapid point of care antigen detection assays with high sensitivity and specificity,” added the document, while inviting applications from manufacturers who produce antigen-based kits. The ICMR has approved seven institutes for validating antigen-based test kits.