Hybrid Immunity

Hybrid Immunity

News: A study has shown that a combination of natural infection with a single dose of vaccine provides greater immunity than either natural infection without vaccination or full vaccination in individuals.

What is the new study?
• People without prior infection but fully vaccinated with the Pfizer or AstraZeneca vaccine showed a decline in neutralising antibodies over a period of three to seven months.
• But the decline was much less in vaccinated people with prior infection.
• People with hybrid immunity had a higher and more durable neutralising antibody response.
• The hybrid immunity offers stronger protection than just infection or full vaccination alone.

What is Hybrid Immunity?
• It is natural immunity from an infection combined with the immunity provided by the vaccine.
• The immunological advantage from hybrid immunity arises mostly from memory B cells.
 

Role of Memory B Cells:
• In immunology, a memory B cell (MBC) is a type of B lymphocyte that forms part of the adaptive immune system.B lymphocytes are the cells of the immune system that make antibodies to invade pathogens like viruses.They form memory cells that remember the same pathogen for faster antibody production in future infections.
• While the bulk of antibodies after infection or vaccination decline after a short while, the memory B cells get triggered on subsequent infection or vaccination.
• The memory B cells triggered by infection and those triggered by vaccination have different responses to viruses.
• Infection and vaccination expose the spike protein to the immune system in vastly different ways.
• After full vaccination, antibodies produced by natural infection continued to grow in potency and their breadth against variants for a year after infection.
• Unlike after vaccination, the memory B cells formed after natural infection are more likely to make antibodies that block immune-evading variants.