As India sees a spike in Covid-19 cases, with numbers crossing 3,666 and the death toll rising to 109, the Indian Council of Medical Research (ICMR) has changed its strategy for testing and has now asked healthcare workers to start rapid antibody-based blood tests to check for coronavirus infections. Rapid antibody tests, if positive, will be followed by a throat / nasal swab test to confirm for Covid-19.  

Aimed to scale testing at mass levels, the decision was taken at an emergency meeting held by the national task force last Thursday. It has advised all States and Union Territories to go for these antibody tests especially in clusters (with containment zones) and in large migration gatherings / evacuees centers.

What the government says

Dr. Raman Gangakhedkar of ICMR told ANI, “We have identified several hotspot areas where large numbers of COVID-19 cases are cropping up and rapid anti-body test is most suitable to detect whether the disease is spreading in the area or not… Also, rapid antibody test give quick results. Once a person is positive for rapid anti-body test, he or she should be quarantined for 14 days and a RT-PCR test should be done as a confirmatory test.”

“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. Vijay Raghavan, principal scientific adviser, government of India, when asked when if further change in the guidelines will be announced, reported The Hindustan Times.

Healthcare workers have also been issued new guidelines saying that all healthcare workers conducting these tests should use gloves, masks and head covers and should follow standard national infection control guidelines.

The ICMR did not open up the test to the private sector, overlooking recommendations by its high-level Covid-19 technical experts committee which wanted the government to open rapid antibody testing to “everyone at risk”, including to those outside hotspot areas. Had the private sector been roped in for the same, the rapid antibody test would have been accessible to both symptomatic and asymptomatic people who don’t fall within the rigid testing parameters that are in place at the moment.

Currently, the RT-PCR test is only available for symptomatic people with a travel history to Covid-19 affected countries, symptomatic contacts of confirmed coronavirus cases, symptomatic health workers, hospitalised patients with severe acute respiratory infections and asymptomatic direct high-risk contacts of infected patients.

At a press conference, answering why the recommendation of making this protocol available to the private sector was not heeded, a senior official of the ICMR said, “It is an evolving situation. We are changing protocols every two or three days to step up our response to the situation.”

How the antibody tests work; pros and cons

Rapid antibody tests, which are as simple as blood glucose tests conducted through a glucose meter, indicate if a person has been infected in the past and has developed an immunity to the virus. The current RT-PCR tests detects the virus’ genetic material (RNA) in throat / nasal swabs to detect a Covid-19 infection.

According to experts, if a person tests positive in the antibody test which is done through blood collection, the throat/nasal swab of that person would be sent for RT-PCR test and the negative cases would be quarantined at home. If the antibody tests come out positive, the ICMR advisory says that that “action as per protocol is to be initiated for isolation, treatment and contact tracing.”

The benefits of rapid antibody testing are many. While only some are trained to collect throat / nasal swab samples, any healthcare worker is trained to draw blood samples. The results from antibody testing are also quicker as opposed to the current method which takes about a day for the results to show.

On the condition of anonymity, a senior health official said, “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. With infections in medical workers rising in India, it will keep our health system intact.”

However, the test shouldn’t be conducted in the first week of infection and the RT-PCR test or the current throat / nasal swab test is said to the preferred and most accurate for testing for the infection. “In epidemics, such as Covid-19, testing for the presence of the viral genome in swabs is the first choice and this is done by what are generically called nucleic-acid tests. These use a method called RT-PCR to detect the viral RNA. RT-PCT tests detect the viral RNA one to two days before symptoms appear and detection remains up to 12 days after symptoms,” said Dr Vijay Raghavan.

Dr. Naveen Dang, Founder Chairman of Dr. Dang’s Labs, one of the ICMR –approved private labs for testing for Covid-19 in India said, “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.”

Statistics

Cases and Labs – As of April 5, 2020, according to official government updates, the country currently has 3,666 active cases, 291 cured / discharged and 109 deaths.

As per ICMR, A total of 89,534 samples have been tested as on 05 April 2020, 9 PM IST. 3554 individuals have been confirmed positive among suspected cases and contacts of known positive cases in India. Today, on 05 April 2020, till 9 PM IST, 9369 samples were reported. Of these, 295 were positive for SARS-CoV-2.

Currently, more than 200 laboratories across the country are involved in testing people for coronavirus. As on April 4, 56 private laboratories are roped in for the same.

Age groups most affected – The Union government has also confirmed that going against the trend, most cases of coronavirus have been found in the age groups of 21 – 40, with 42 percent of them belonging to the age group. The next most-hit age group is those between ages 41 and 50, which compromises of 33 per cent of the Covid-19 positive cases in the country. Senior citizens (60+), who are otherwise the most high-risk group for the viral infection, form 17 per cent of the Covid-19 patient group in India.

Only 9 per cent of those below 20 years of age have been found to be coronavirus positive, the health ministry said.

Young Indians are at higher risk of contracting the disease as 83% of the patients are under the age of 50.

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