Many cases have come to light where people who have taken the third dose of vaccines are also reported to have contracted the Omicron, the new variant of Sars-Cov-2.
Omicron Variant Update: Covid vaccines have been developed from the original strain of Coronavirus so they help produce an antibody that is effective against the original strains only, said an expert on failure of the vaccines to stop the new Covid-19 variant.
Many cases have come to light where people who have taken the third dose of vaccines are also reported to have contracted the Omicron, the new variant of Sars-Cov-2.
For instance, in a recent report, the Brihanmumbai Municipal Corporation (BMC) has found an Omicron-infected person who had taken three doses of Pfizer vaccines. This 29-year-old man with a travel history to the US was Covid-19 positive and his swab sample, after genome sequencing, confirmed the presence of Omicron virus.
Though Pfizer Inc and its associate BioNTech have claimed that its third dose, also called the booster dose, can increase antibodies 25 fold and help in neutralising the Omicron, a section of experts who work on the immune system doubt these claims.
According to them, none of the vaccines available in the market today can fully protect a person from Omicron because it’s a new variant whereas vaccines can produce antibodies against the original strain of the virus and not against the variants.
Noted immunologist, Gobardhan Das, who is Professor of Molecular Medicine at Jawaharlal Nehru University said, "Vaccines have been developed from the original strain of the virus. So, these vaccines help produce an antibody that is effective against the original strains only. Unless there is a cross-reactivity, It cannot prevent the new variants like Omicron which has 32 mutations in its spike protein.”
“So even if a person is vaccinated with a booster dose, the body will make antibody against the original strain only. Hence booster doses are as ineffective as the first and second dose of a vaccine for a new variant like Omicron,” he added.
Dr Syamal Roy, a noted immunologist who retired as Head of the Department of Infectious Diseases and Immunology, Indian Institute of Chemical Biology, Kolkata agrees with Prof Das and said, “Vaccines are made out of viruses only. So if a vaccine has been made from a particular variant of the virus, it will work only against that particular variant. In case the virus mutates, the vaccine might not provide protection against the new variant. That is why vaccines have failed to stop the infection from Omicron.”
He adds, “The second reason could be the decrease in the level of antibody due to which a vaccinated person can get re-infected.”
Both Dr Roy and Dr Das agree that there is a complete lack of research on whether vaccines are generating memory cells that can provide long-lasting protection from the virus.
According to experts, when a person is vaccinated or naturally infected, his or her body produces two kinds of protection, first is the antibody and the second is the memory cell. The memory cells, also known as T-Cell and B-Cell, memorise the virus and if it tries to enter the body in future, these cells help the body to quickly produce antibodies to fight against it.
Prof Das even goes on to say that vaccines might not be producing long-lasting memory cells that can provide long term protection from the virus.
“The longevity of the memory response depends on the type of T-Cell that the vaccine makes. There are two types of T-cell. One is Central Memory T-Cells that can give memory for four to five years. The other one is Stem cells like Central Memory T- Cells that can produce long-lasting memory. No research has been done so far to test whether vaccines are producing T-cells and if they are producing, what kind of T-cells they are.
Prof RM Pitchappan, an eminent immunologist and currently the Honorary Visiting Professor of Biology in the Madurai Kamaraj University agrees that vaccines often don’t work against new variants but, besides, he says that some people’s immune systems don’t respond to vaccines at all.
“Some people’s immune systems don’t respond well to the vaccination and hence they don’t get the expected immunity,” Prof Pitchappan said.
Despite the challenges that the new variant has posed for vaccine science, the majority of experts agree that vaccine might not be able to stop the transmission, however, it is quite effective in preventing the severity of the disease and hospitalisation.
“So, the vaccine might not help in preventing the virus or its variant from entering the body due to various reasons, it activates the overall immune system that can tackle the virus inside the body and doesn’t let the virus cause a severe disease,” Dr Roy said.
He added, “Hence a person who is not naturally recovered from Covid-19 must take the vaccine.”