Memory B cells can mutate, to some extent, when exposed to a new strain. This process is known as affinity maturation. The transformation occurs in transient structures in the lymph nodes - called terminal centers. Researchers have also looked at whether the immune system can deploy entirely new B cells when faced with a new infection.
Imprinting is a quirk of the immune system in which someone’s initial exposure to a virus biases their immune response when they meet the same virus again.
Studies are showing how imprinting shapes people’s responses to SARS-CoV-2; those infected with earlier strains can mount weaker responses to a later Omicron infection.
This phenomenon is dampening the hope that variant-tailored boosters will markedly reduce transmission of the virus, although researchers agree that variant-tailored boosters are worth getting because they still provide some immunity, and prevent serious illness.
This is an audio version of our Feature: How your first brush with COVID warps your immunity
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