India is testing for Covid-19 antibodies, but unlikely to let recovered patients move freely
New Delhi: Are you among the 400-odd Indians who have recovered from the Covid-19 infection? It’s unlikely you will be allowed to break lockdown protocol since India isn’t considering adopting the ‘German model’ that allows people with antibodies to the virus to step out.
The government on 4 April had advised conducting antibody tests in containment zones. The test shows if a person, once infected by the coronavirus, has developed the immunity to it.
“We deliberated on considering the person fit after he tests positive for antibody IgG, but it is not a very good thing to do … There have been instances when the duration of viral shedding is long and unknown,” Nivedita Gupta, senior scientist at Indian Council of Medical Research (ICMR), the country’s apex health research body, told ThePrint.
Gupta cites the example of an Indian who had returned from the Congo in 2015 during the Ebola outbreak and was quarantined at Delhi airport. The person had kept shedding the Ebola virus for about 150 days, whereas the benchmark time known was 90 days. So there is no thumb-rule for such things, she said.
Currently, there is no known cure, treatment or vaccine for the novel coronavirus that has caused the Covid-19 pandemic, killing more than 83,600 people worldwide, and infecting over 1.45 million. In India, there are nearly 5,000 active cases.
How antibody test works
The human body, Gupta explains, develops two kinds of antibodies — immunoglobulin M (IgM) and immunoglobulin G (IgG).
“For most infections, it takes five to seven days for the body’s immune response to develop IgM antibodies. Even when IgM develops, the person may still be shedding the virus. In another 10-14 days of illness (depending on other host factors and type of illness), IgG antibodies are developed in the body,” she explained.
These remain in the body from between a month to a year, or even longer in some cases. When a person is IgG-positive, it means that the person has been exposed to the infection and their body has developed the immune response.
A majority of the rapid antibody testing kits being rolled out in India don’t indicate separate results for IgM and IgG. “In an ideal scenario, we would like to understand the prevalence of both IgM and IgG antibodies separately. For coronavirus, we are trying to ramp up the testing capacity. At present, antibody kits are available which only show the presence of antibodies, without distinction between IgG and IgM,” Gupta said.
“While the patient is releasing IgM (early antibody), he must be shedding virus, but even when he/she is releasing IgG (later antibody), we aren’t sure if they (the person) are virus-free or still a viral shedder,” she added.
The German model
Germany has undertaken a study to give “coronavirus ‘immunity certificates’ to facilitate the transition of recovered coronavirus patients out of quarantine and into society.”
Planned by German researchers in the Helmholtz Center for Infection Research (HZI) in Braunschweig, the research project will investigate the prevalence of coronavirus antibodies.
According to international reports, Germany is going to give one lakh people coronavirus antibody tests in the coming weeks as part of a trial to get millions of workers out of lockdown.
European governments are also considering handing out these “immunity passports” to let individuals who have had the virus return to a more normal life.
However, German scientists, according to The Washington Post, have cautioned that “this stage of the response is still a long way off”.
“There remain crucial questions over how long someone’s immunity might last and at what level, and there are concerns about tests producing false positives and insufficient capacity for widespread testing,” the report .
The print
