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What is Immune Imprinting?


Since last September, countries like the UK and the US have rolled out variant-specific or bivalent boosters, in the hope that they would provide better protection against the coronavirus infection in comparison to the original vaccine. However, a slew of recent studies has shown that a phenomenon in our bodies, called immune imprinting, might be making these new boosters far less effective than expected.


GS II: Health

Dimensions of the Article:

  1. What is immune imprinting?
  2. What are the findings of the recent study?

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.
How it works?
  • Over the years, scientists have realised 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.

Problem with Imprinting

  • 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.

What are the findings of the recent study?

  • Two studies were conducted by researchers at Columbia University Vagelos College of Physicians and Surgeons in New York and Beth Israel Deaconess Medical Center in Boston
  • The studies showed that the bivalent booster vaccine did not elicit a superior virus-neutralizing peak antibody response compared to the original monovalent vaccine
  • Immune imprinting may be a hurdle in the success of variant-specific vaccines
  • An earlier study by Imperial College London observed that Omicron infection had little or no beneficial effect of boosting any part of the immune system among participants who had been imprinted with older coronavirus variants
  • The World Health Organization has cautioned that the bulk of the benefit is from the provision of a booster, regardless of whether it is a monovalent or bivalent vaccine
  • Scientists suggest that regardless of the type, coronavirus vaccines are crucial in staving off serious illness
  • A need to come up with a vaccine that can overcome imprinting and thwart the transmission of the virus.

-Source: Indian Express

December 2023