The imprinting effect of covid-19 vaccines: an expected selection bias in observational studies

Antigenic variation in the SARS-CoV-2 omicron variant and subvariants are substantial compared with previous variants and covid-19 vaccines used until September 2022. The concerns are that past exposure to previous variants—through infection or vaccination—could alter the immunological response to an omicron related infection in such a way that the immune response to successive omicron infections would be impaired.123 This so-called “immune imprinting hypothesis” has been used to suggest that a vaccine booster in individuals who later are infected with omicron increases the risk of a second omicron infection.45 If this effect of immune imprinting truly exists, recommendations for additional vaccine doses may need to be re-evaluated.Summary pointsRecent observational studies found a higher risk of reinfection with omicron in people who received a third booster dose and then acquired a first omicron infection, and this finding was attributed to immune imprinting; however, this article shows that such a result is expected…
Read Original Article: The imprinting effect of covid-19 vaccines: an expected selection bias in observational studies »