Professor Gobardhan Das, a well-known immunologist who is associated with the Special Centre for Molecular Medicine, Jawaharlal Nehru University, heaps praise on the government’s current vaccination drive as one of the most successful in the world. However, he is worried about the lack of research regarding the long-term benefits of vaccines.
He says that government research agencies should conduct more studies to assess the long-term benefits of the two vaccines – Covishield and Covaxin.
A fellow of the Indian Academy of Science with a specialisation on immunology, infectious diseases and cell biology, Prof Das spoke to Outlook on various issues related to the role of immunologists in the pandemic, the current vaccination drive in India and its long-term impact. Excerpts:
As everyone is obsessed with the development of antibody post-vaccination, do you think it is the right way to assess the protection against the virus Sars_Cov_2?
Unfortunately, it is not. Measuring antibody post-vaccination and assessing its presence in the body for three or six months doesn’t make any sense unless we measure the long-term benefits of the vaccines. The important question is, can the vaccines provide protection for a longer duration of time or many years. We cannot afford to vaccinate the whole population every year. If the vaccine protection is transient, then it will leave the vaccinated population vulnerable to infection after a few months.
Do you mean to say that government research bodies are not conducting any studies on the long-term benefits of the vaccine?
We are mostly measuring antibody formation as the major benefit of the vaccination. But no research is happening in the country about the cell-mediated response which provides protection for many years and sometimes for the whole of life. The important question is, do these vaccines prompting the formation of memory B-cells and T-cells in the body? These cells not only fight against the virus but also acquire memory. They have the ability to memorise the antigen, ie Sars_Cov_2 and whenever the virus enters the body, these cells can help produce immunity against the virus and finish them.
During the course of the clinical trials, it was found that both the vaccines provide a cell-mediated immune response, which means, they do help develop memory B-cell and T-cell. So why are you so apprehensive about their ability to prompt these memory cells?
There are two very important aspects that we must understand in the context of vaccines’ ability to produce B-cell and T-cell. If a person, after vaccination, showing the presence of these memory cells in its blood, it doesn’t mean that these cells are specific to the virus Sars_Cov_2. Our body produces these memory cells against several other diseases or infections. Also, the process of current vaccination also helps the body produces these cells. But these cells are only useful if we are sure that they can neutralize the virus. We will come to know only when we take these cells from the blood of a vaccinated individual and then determine if they are specific to Sars_Cov_2. With the process of, what we call is tetramer staining, one can easily determine antigen specificity.
This is the first stage in which it is established that these cells are Sars_Cov_2 specific.
Now the next stage is to find out what kind of longevity these T-Cells have. How will you determine it? Nowadays, there are some markers that can tell us the life span of these T-Cells.
So, what you mean to say is that those people who were vaccinated, let’s say, eight or nine months ago as clinical trial volunteers, their memory cell type can be investigated to find out their life span?
Yes, we can find out both. First, whether the B-cells or T-cells Sars_Cov_2 specific or not, and second, what types of memory cells do they have?
There are divisions among memory cells. For example, there is something called an effector memory cell which simply goes and kills the virus and then dies. Then there is something called the central memory cell which survives for a good length of time for a few years.
Another group, which survives for life long, is stem cell-like memory cells.
So, if those clinical trial volunteers have stem cell-like memory cells, then it shows that the vaccine can provide protection for the whole of life. It is not something impossible. It can be done but I don’t understand why the research bodies are not doing it.
Is it possible that the B-Cell or T-Cell, developed post-vaccination, fail to kill the Sars_Cov_2 also?
Of course. It is very much possible. It is because the vaccine doesn’t have the real virus. It has either the dead virus or a part of the virus-like spike protein. So, it might prompt cellular-mediated response and the investigation of blood samples of such vaccinated people might show the presence of B-cell and T-cell. So, you have to do the tetramer staining as discussed above to find out if they are antigen-specific.
Let’s hypothetically think that vaccines are developing no or short-term memory cells. What will happen in that case?
You come back every year and vaccinate again which is not possible at least for the Sars_Cov_2. That’s why I am worried. So one has to find it out whether memory cells are generated or not. And if yes, then what type of memory cells are these?
I tried to convey this message many times and at many platforms.
Many scientists are of the view that those who have recovered naturally, don’t need to be vaccinated. What’s your take on this?
Yes, I fully agree with this view. Those who have got naturally infected, whatever be the vaccine efficacy, don’t need any vaccine at all. Whether these people have generated the immune response, or for how long is the immune response effective are the questions to be examined on these people, however, I say they are the best-protected people.
Being an immunologist, do you think this branch of science is being given due importance by the government in the fight against Covid-19?
I request the government to accommodate some eminent immunologists in their committees which take vaccine-related decisions. I believe there is a lack of understanding so far as the role of immunology in the fight against Covid-19 is concerned.
