Correspondence Address:
Dr. Suraj Kapoor
Department of Community Medicine, Armed Forces Medical College, Solapur Road, Wanowrie, Pune - 411 040, Maharashtra
India

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Original antigenic sin also known as antigenic imprinting was first described in 1960, by Francis,[1] while studying the response to seasonal flu revaccination, with the lesser immune response on re-vaccination. It is the phenomenon in which, after subsequent exposure to a different antigen variant of the same virus, the immune system produces antibodies of lesser strength and specificity. This immune trapping mechanism is also known as “Hoskins' paradox” or “negative interference,” which means that with another vaccination for a virus that uses antigenically dissimilar strains, the immune system and, to a lesser extent, decreasing the protective efficacy of the second vaccine.[2],[3]

In revaccination, the body's defence system utilizes the initial imprinting and simply alters the B-cell clonotypes, modifying them to the new antigen. This phenomenon leaves persons with a restricted, preestablished immune response.[4] A similar phenomenon of original antigenic sin has been established for viruses such as dengue and human papillomavirus.

Many countries across the globe are thinking of giving second boosters to the population. However, the recently published literature done among non-human primates suggested regardless of whether the booster was from the original vaccine or the Beta-specific version, similar increases in neutralizing antibody levels were observed,[5] indicating a possible original antigenic sin mechanism for the COVID-19 and its mutants. Hence, health policymakers and government officials should develop scientific and authentic policies for further booster dosages against COVID-19. This is particularly important in the context of existing variants of concerns. It would be a prudent and efficient strategy to limit further boosters for the vulnerable population only rather than going for mass vaccination.

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