In Context
- Recently, studies have found ‘immune imprinting’ might be making bivalent boosters less effective.
More about the news
- About:
- 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, studies have shown that a phenomenon in our bodies, called immune imprinting, might be making these new boosters far less effective than expected.
- 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.
- Bivalent boosters:
- Bivalent boosters are made to counter both the Omicron strains and the original Covid-19 strain.
More about immune imprinting
- Meaning:
- 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.
- Origin:
- 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”, according to a report published in the journal Nature.
- At the time, it was termed the ‘original antigenic sin’ but today, it’s commonly known as imprinting.
- The phenomenon was first observed in 1947, when scientists noted that
- How does it work?
- Over the years, scientists have realised that imprinting acts as a database for the immune system.
- It helps 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.
- Over the years, scientists have realised that imprinting acts as a database for the immune system.
- Issue:
- 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.
- The problem occurs when a similar, not identical, variant of the virus is encountered by the body.
- Ways to deal with immune imprinting
- Nasal vaccines: 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.
- Spacing vaccine shots: Researchers are also trying to find if spacing out coronavirus vaccine shots on an annual basis, could help with the problem of imprinting.
- Nasal vaccines: Some scientists have said nasal vaccines might be better at preventing infections than injected ones.
Pan-sarbecovirus vaccines: There’s also considerable effort directed toward developing what’s called pan-sarbecovirus vaccines that will protect against all COVID-causing variants and maybe even protect against other SARS and related viruses.
