Scope of antibody tests rigid despite panel push

about why the recommendation was not heeded. He spoke on condition of anonymity. On April 2, ICMR’S interim advisory expanded rapid antibody testing to hot spot areas.

Unlike the RT-PCR test that detects the virus’s genetic material (RNA) in throat swabs to diagnose a current Covid-19 infection, rapid antibody tests indicate if a person has been infected in the past and has developed and immunity to the virus. Experts say they can also be used as a screening test for the infection -- antibodies typically show up a week after the infection.

The simple blood test (samples can be collected by just a finger prick) which takes 15-20 minutes to give results, identifies people who were infected at least a week before the test, and also those who were infected but never diagnosed, helping map undetected infections and giving the correct extent of the spread of the disease.

While China and Singapore have used antibody tests to scale up testing and track infections, Germany, Italy, Britain and the US, plan to use it to get those who are immune back to work, keep those infected quarantined, and those with no immunity locked down.

The US approved the country’s first antibody test on Friday.

“Rapid antibody testing will help us measure how widespread the infection is in the community, how long immunity works, and get the recovered back to work, which will help meet critical staff shortfalls in hospitals and end lockdowns in a phased manner to restore a semblance of normal,” said a person on the technical committee who asked not to be named. “With infections in medical workers rising in India, it will help keep our health system intact,” he said.

The Maharashtra government and the Brihanmumbai Municipal Corporation (BMC) have already announced on Friday that all its health workers will be tested using the rapid antibody test to detect if they have been infected and developed immunity to the virus.

“Who is to be tested and the scale of testing is notified by the health ministry, and updated from time to time. These are to be followed,” said Dr K. Vijayraghavan, principal scientific adviser, government of India, when asked when if further change in the guidelines will be announced.

Antibody tests have the potential to take testing to scale, and companies are racing to meet the anticipated increase in demand. On Friday, Bangalore-based Bione launched a Covid19 homescreening test kit, and the US approved Cellex for lab-based antibody testing. Pathologists expect the market in India to be flooded over the next few weeks following approval, which is expected next week. The National Institute of Virology, Pune, has already validated 11 Ce-approved rapid antibody testing kits from the European market, and five from other parts of the world, including one from India.

Bione’s product has been approved and is available.

“Finger-prick tests are fairly simple to do but chances of false negatives are high if the test is done in the first of week of infection. Antibody tests should look for immunoglobulin M (IGM) in the second week, and for immunoglobulin G (IGG) after the third week, to deliver accurate results. It still will not indicate how strong the immune response is, and for how long it will last,” said Dr Naveen Dang, founder chairman of Dr Dangs Labs, which is one of the Icmr-approved private labs testing for Covid-19 in India.

Several experts say that people who have antibodies are unlikely to get reinfected soon after recovery. “Obviously, antibody-positive persons can be declared as immune to Covid-19 and get free from social isolation. They won’t get infected or infect others,” said a public health specialist, requesting anonymity.

The body responds to infection by generating two types of antibodies. IGM is generated first, at