BENGALURU : While scientists and experts are still working on how the new SARS-CoV-2 variant evolved, there is a working hypothesis which says this variant came from a chronically immunocompromised patient who was treated with human convalescent plasma to protect against COVID-19.
Epidemiologists in India claim that a study needs to be done to see if there is possibility of a similar occurrence in India. "We may not find the same strain, but there may be chances of finding different strains. Hence, it becomes important for the country to go back and examine all those chronically immunocompromised people who were given plasma therapy," said Dr Giridhara Babu, senior epidemiologist and adviser, COVID-19 Task Force Committee.
Dr Babu said that the earlier strain was sort of incomplete, and could not elicit effective antigen and receptor binding. The new strain seems like a perfect lock and key fit, and hence, the infectiousness is high. A report by COG-UK Consortium Scientists said they found this new strain in a patient who is immunocompromised and was on plasma therapy.
According to a senior virologist, immunocompromised patients are generally treated with convalescent plasma once or more, and also put on the drug Remdesivir. A study done earlier by other researchers has shown that plasma therapy given when the viral load is high, leads to increased virus genetic diversity.
Explaining the report further, Dr Giridhara Babu said that immunocompromised patients don’t have a natural 'immune' response. "Their immune system is like a blank slate with not much ability to mount an attack against the virus. Hence, when we give a passive antibody which is received from someone else, for a longer time, the virus goes through these kind of modifications. Virus genome sequencing reveals an unusually large number of nucleotide changes and deletion mutations. Convalescent plasma, when given when viral load is high, is found to be associated with genetic diversity," he said.
However, Dr Vishal Rao, Head and Neck Oncologist at HCG who was the first to implement convalescent plasma therapy in Karnataka, said, "This is only a hypothesis without experimental proof, where they have assumed that tachyphylaxis lead to point mutations which could be from antivirals, monoclonal antibodies or any other therapy against the virus. They should include Remdesivir or steroids too as potential reasons. It is too far-fetched and in the current scenario with no treatment, we would end up killing all hopes of patients."
Also, till the arrival of the many vaccines, he suggests that plasma therapy remains a method of treatment and has seen a good number of recoveries.