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- Scientists suggest that regardless of the type, coronavirus vaccines are crucial in staving off serious illness. But studies have found that ‘immune imprinting’ might be making bivalent boosters less effective.
What is immune imprinting?
- Immune imprinting is a tendency of the body to repeat its immune response based on the first variant it encountered — through infection or vaccination — when it comes across a newer or slightly different variant of the same pathogen.
- The phenomenon was first observed in 1947, when scientists noted that “people who had previously had flu, and were then vaccinated against the current circulating strain, produced antibodies against the first strain they had encountered”. At the time, it was termed the ‘original antigenic sin’ but today, it’s commonly known as imprinting.
- Over the years, scientists have realized that imprinting acts as a database for the immune system, helping it put up a better response to repeat infections.
- After our body is exposed to a virus for the first time, it produces memory B cells that circulate in the bloodstream and quickly produce antibodies whenever the same strain of the virus infects again.
- The problem occurs when a similar, not identical, variant of the virus is encountered by the body. In such cases, the immune system, rather than generating new B cells, activates memory B cells, which in turn produce “antibodies that bind to features found in both the old and new strains, known as cross-reactive antibodies.
- Although these cross-reactive antibodies do offer some protection against the new strain, they aren’t as effective as the ones produced by the B cells when the body first came across the original virus.
Recent study pertaining to CoronaVirus Vaccine:
- It was observed that the bivalent booster shots “did not elicit a discernibly superior virus-neutralising peak antibody response as compared with boosting with the original monovalent vaccines” across all coronavirus strains tested - Columbia University.
- The findings suggested immune imprinting might be posing a hurdle in the success of the bivalent or variant-specific vaccines.
How to circumvent immune imprinting?
- Currently, several ongoing studies are trying to find a way to deal with imprinting. Some scientists have said nasal vaccines might be better at preventing infections than injected ones. They believe the mucous membranes would create stronger protection, despite carrying some imprint of past exposure.
- Researchers are also trying to find if spacing out coronavirus vaccine shots on an annual basis, could help with the problem of imprinting.
What are B-cells?
B-cells are the type of cells that produce antibodies to fight bacteria and viruses. These antibodies are Y-shaped proteins that are specific to each pathogen and are able to lock onto the surface of an invading cell and mark it for destruction by other immune cells.
A type of white blood cell. T cells are part of the immune system and develop from stem cells in the bone marrow. They help protect the body from infection and may help fight cancer. Also called T lymphocyte and thymocyte.
There are two main types of T-cells:
Helper T-cells stimulate B-cells to make antibodies and help killer cells develop.
Killer T-cells directly kill cells that have already been infected by a foreign invader.