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.

"[Immune imprinting] could be a problem if the person was unable to mount a useful immune response against a new variant," Dr. Stanley Perlman, an immunologist and microbiologist at the University of Iowa, told The Epoch Times. He was not involved in the study.

While that did not occur in this study, most of the antibodies made following vaccination targeted the original COVID-19 variant and not XBB.1.5. 

Surprising Findings

"Imprinting is not a new concept, but the situation we are looking at seems to be quite unique," said David Veesler, who has a doctorate in structural biology, is a professor and chair in the Department of Biochemistry at UW, and an investigator with the Howard Hughes Medical Institute, in a press release.

Immune imprinting is a well-recognized phenomenon that can occur with other infections and viruses.

New influenza infections distinct from previous variants can overcome imprinting from influenza vaccinations and infections.

However, in the UW study, immune imprinting persisted even among those infected with new omicron variants.