Immune imprinting

• Recent research suggests that "immune imprinting" may reduce the effectiveness of bivalent boosters.

More on the news:

• With the aim that boosters would offer superior protection against the coronavirus infection compared to the original vaccine, nations like the UK and the US have introduced variant-specific or bivalent boosters.
• Studies have revealed that immunological imprinting, a characteristic of our body, maybe render these new boosters much less effective than anticipated.
• Bivalent energizers: To combat both the Omicron strains and the initial Covid-19 strain, bivalent boosters are created.

About Immune imprinting:

• When exposed to a newer or somewhat different form of the same pathogen, the body has a tendency to repeat its immune response depending on the initial variant it encountered through infection or vaccination. This process is known as immunological imprinting.
• According to a publication in the journal Nature, the phenomenon was first noticed in 1947 when researchers saw that "People who had previously had flu, and were then immunised against the current circulating strain, developed antibodies against the original type they had seen."
• Imprinting is now a common name for what was once called the "initial antigenic sin."
• Working: When our body is initially exposed to a virus, memory B cells are created. These cells circulate in the bloodstream and rapidly manufacture antibodies if the same viral strain re-infects.

How does it function?

• Scientists have come to understand that imprinting serves as the immune system's database throughout time.
• It enables a stronger defence against recurrent infections.
• When a virus enters our body for the first time, memory B cells are created. These cells circulate in the bloodstream and rapidly manufacture antibodies if the same viral strain re-infects.

Are the booster doses totally ineffective?

• There is some protection against the new strain provided by these cross-reactive antibodies.
• They are not as powerful, though, as the ones the B cells made when the body first encountered the original virus.

How may immunological imprinting be avoided?

• Several ongoing investigations are now looking for a solution to imprinting.
• Some scientists have suggested that nasal vaccines may be more effective than injection-based ones at preventing illnesses.
• Even if the mucous membranes have some remnants of previous exposure, they think they would provide stronger protection.
• Additionally, scientists are examining if giving annual intervals between coronavirus vaccinations could lessen the issue of imprinting.

Problem:

• When the body comes into contact with a comparable but distinct variant of the virus, a problem arises.
• In such circumstances, the immune system activates memory B cells instead of producing new B cells, which in turn make cross-reactive antibodies—antibodies that bind to characteristics shared by both the old and new strains.
• Although some defence against the new strain is provided by these cross-reactive antibodies, they are not as potent as the ones created by the B cells when the body first encountered the original virus.

Solutions for immunological imprinting:

• Nasal vaccines: According to some experts, nasal vaccines may be more effective than injection-based ones at preventing illnesses.
• Even if the mucous membranes have some remnants of previous exposure, they think they would provide stronger protection.
• The issue of imprinting may be resolved by spacing out vaccinations. For example, coronavirus vaccine injections may be spaced out annually.
• The development of so-called pan-sarbecovirus vaccines, which will provide protection against all COVID-causing variations and perhaps even more SARS and related viruses, is another area of intense research.