Immune imprinting occurs when previous exposures leave such a strong immune memory that the body continues to produce antibodies targeting the past experience.

People who have taken at least three doses of the original version of the COVID-19 mRNA vaccine have been strongly immune imprinted, a study by the University of Washington (UW) found.

Consequently, when vaccinated with the most recent COVID-19 XBB.1.5 mRNA boosters, recipients produced few to no antibodies specific to the XBB.1.5 variant.

Immune imprinting occurs when previous infections or vaccinations leave such a strong immune memory that the body continues to produce immune cells and antibodies targeting the previous immune experience—even when exposed to a new variant or vaccine.