Many people haven’t developed any antibodies despite taking both doses of either of the two vaccines – Covishield and Covaxin.
There have been many reports in which vaccine beneficiaries have got their antibodies tested and didn’t find the presence of any immunity against the virus.
Gyaneshwar Chaubey, a professor of genetics at Banaras Hindu University (BHU), who is researching antibody formation among vaccinated and naturally infected people, says that many of the elders didn’t develop any antibodies even after two doses.
“This is quite intriguing. After testing 2309 individuals we didn’t find even a single naturally recovered individual who didn’t develop Sars-Cov-2 specific antibodies but it is not true for all vaccinated people,” Prof Chaubey said.
As antibody is associated with a person’s ability to fight against Covid-19, people are worried about their safety.
Their concern seems genuine as there are a few reported cases of death due to breakthrough infections (post-vaccinated infection).
One of the most prominent faces in the country who lost the battle against Covid-19 was well-known cardiologist Dr KK Aggarwal who was fully vaccinated but hadn’t developed any antibody.
Some government doctors working in Covid wards have shared anecdotal experiences with Outlook in which they confirmed that there are more cases in the country one like Dr Aggarwal.
“We don’t know whether the virus or its mutants are virulent enough to overpower the body’s immune system or there was no immunity in the body post-vaccination to fight against the disease,” a doctor in a government Covid ward, said.
Now the question is, “Since a significant number of people are not showing any antibody, are they safe from Covid-19?
Before answering this question, let’s first understand how our immune system works against the virus.
How immune system works?
Immunologists say that when a person is naturally infected, his immune system produces two types of response, humoral and cellular.
Under humoral response, different types of antibodies are formed such as a general antibody, neutralizing antibody, anti-spike antibody to name a few. These antibodies fight against the virus.
At the same time, the cellular response also gets activated which is also known as a T-cell response.
“T cells recognize the virus and help (T helper cells) B cells to produce antibodies. In another direction, some of them become CTL and offer an immunity by killing the virus-infected cells of our body. That is how viremia settles down,” Prof RM Pitchappan, a well-known name in human immunogenetics and also a visiting professor at Madurai Kamaraj University said.
Prof Gobardhan Das from Special Centre for Molecular Medicine, Jawaharlal Nehru University says that along with providing protection, T-cells also memorize the antigen so that next time when the same antigen attacks the immune system, it can help develop antibodies faster.
These experts also say that while humoral immunity response disappears after a few months, cellular immunity remains for a longer duration. The research is going on in the West that how long this Cellular immunity sustains in the body. Some studies have hinted that it can sustain for a few years to the rest of the life as well.
Can a vaccinated person develop only T-Cells but not antibodies?
Now the next important question is, “Is there a possibility that after vaccination the human body develops cellular-mediated response without developing any humoral response?
The Ministry of Health and Family Welfare has answered in affirmative on several occasions in its regular press conferences to dispel the fear among such vaccine beneficiaries.
In a recent government release, Dr VK Paul, Member (Health), NITI Aayog, was quoted as saying, “Some people seem to be thinking of getting an antibody test done post-vaccination. But that is not required to be done for the simple fact that antibodies alone do not indicate the immunity of a person.”
“This is so because of T-cells or memory cells; these undergo certain changes when we receive the vaccine, they become stronger and gain resistance power. And T-Cells are not detected by antibody tests as these are found in bone marrow,” Dr Paul added.
Dr Paul hasn’t quoted any research done anywhere to find out if a vaccinated person can develop a strong and resistant T-cell without developing any type of initial humoral response or antibodies.
Interestingly, during the Phase II clinical trial of both the vaccines, it was found that both Covishield and Coivaxin develop humoral as well as cellular immune responses.
There is no instance in which they develop only cellular response and not the humoral response.
Many health experts say that they are not aware of any study done to look at this particular aspect of the vaccine.
“In the case of other viral diseases like HIV, this is true that the body develops a cell-mediated response,” Prof Pitchappan said.
He added, “However, I have no idea, whether anybody in ICMR, CSIR or various hospitals handling Covid patients have done any research to find out if vaccines develop cellular immune response without forming any kind of antibody,”
Prof Pitchappan also clarifies that T-cells reside in lymph nodes and there are about 460 such lymph nodes in a human body.
Dr. D Nageshwar Reddy, Chairman, Asian Institute of Gastroenterology, Hyderabad, which recently conducted a study to show how a ‘Single Dose’ of vaccine sufficient for those already infected with COVID-19, says, “There is no research done to find out that a person can develop cellular-mediated response without having humoral response initially.”
Since there is no evidence-based research, experts’ views vary.
“I believe that the body may make T-cell without developing any antibody at the initial stage,” Dr Reddy said.
Prof Chaubey says, “To me, it looks like there are three broad categories of people. First, who develop antibodies; second, who didn’t develop antibodies but do develop B and T cells and third who don’t develop anything and this is possibly due to their genetic makeup.”
Dr Sanjay Rai, Professor at the Centre for Community Medicine, AIIMS agrees with Dr Choubey and says, “There are two possibilities. The higher possibility is that such people have neither developed any humoral response nor cellular response. The second probability is that they might have developed the cellular response without showing any sign of humoral response, i.e. antibody.”
Since there are two contradictory hypotheses, the important question is how to protect such vaccinated beneficiaries from falling prey to Covid-19?
Protecting vaccinated people with no antibody
Immunologists and other health experts say that it is easy to test the cellular-mediated response of these categories of the vaccinated population by the government and take a corrective step.
Prof Gobardhan Das from Special Centre for Molecular Medicine, Jawaharlal Nehru University, says that like antibody the government can also find out whether the person has developed any cellular immunity, B-Cell or T-Cell, response after vaccination.
Prof Das highlights another important aspect as he says, “Another cause for concern is that we have no idea that even if there is a cellular immune response, it is quantitatively high to provide adequate protection.”
“Merely saying that they have developed cellular-mediated response doesn’t serve any purpose. They are like a lame duck who is as vulnerable to infection as a naïve person,” Rahul Bhargava, Head of Hematology Dept, Fortis Gurgaon said.
Very few hospitals have facilities in their labs to test the presence of B-Cells or T-Cells and it is done mainly for research purposes.
There is no private lab in India that conducts tests to check the presence T-Cell and its neutralizing capabilities against Sars_Cov_2.
Big diagnostic labs say that it cost about Rs 20 lakh to have the whole set-up and then each test costs about Rs 6000. So even if an individual wants to get his cellular immunity tested, he can’t get it done in India.
“Besides, there is no clarity on regulation that if an individual can be allowed to get his cell-mediated response test done, so private labs haven’t started any such facility in India,” Dr Bhargava said.
Health experts also say that a common man doesn’t need to go for any T-cell test and the government should take care of these issues on the research level.
“It adds on another test and burden to the public. I don’t think it is required for a common man to go for it. Let the government take care of such people who have issues in developing antibodies. They should be given an additional booster dose,” a prominent doctor in a government hospital said.