"Original Antigenic Sin" in SARS-CoV-2 Vaccination Followed by Infection

Area of Science:

• Immunology
• Vaccinology
• Virology

Background:

• Original antigenic sin (OAS) is a predicted phenomenon impacting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant responses.
• Evidence on OAS's effect on coronavirus disease 2019 (COVID-19) vaccine safety and effectiveness is limited.

Observation:

• A case study of a 39-year-old healthcare worker presented with delayed pruritus and injection site discomfort.
• Symptoms recurred 13-18 months post-vaccination with an inactivated SARS-CoV-2 vaccine.
• The patient developed COVID-19 shortly after symptom onset, with a documented erythematous papule.

Findings:

• High serum titers of immunoglobulin M (IgM), immunoglobulin E (IgE), and SARS-CoV-2-specific immunoglobulin G (IgG) antibodies were detected five weeks post-symptom onset.
• These immunological findings suggest a link between prior vaccination and the response to a subsequent natural infection.

Implications:

• Original antigenic sin (OAS) is a plausible explanation for delayed vaccine side effects in individuals vaccinated with inactivated SARS-CoV-2 vaccines who experience secondary wild virus exposure.
• This highlights the importance of considering OAS in the context of evolving SARS-CoV-2 variants and vaccination strategies.
• Further research is needed to fully understand the implications of OAS on vaccine efficacy and safety in the long term.