Long-Term Dynamics of SARS-CoV-2 Variant-Specific Neutralizing Antibodies Following mRNA Vaccination and Infection

Area of Science:

• Immunology
• Virology
• Vaccinology

Background:

• Long-term antibody dynamics post-vaccination and infection are crucial for understanding SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) protection.
• Evaluating vaccine efficacy and informing strategies for booster doses require insights into neutralizing antibody persistence.

Purpose of the Study:

• To analyze the long-term dynamics of SARS-CoV-2 neutralizing antibodies over three years following mRNA vaccination and natural infection.
• To assess antibody responses against various SARS-CoV-2 variants, including Omicron subvariants, and compare vaccine-induced immunity with hybrid immunity.

Main Methods:

• Longitudinal analysis of 114 serum samples from 19 individuals over six time points spanning three years.
• Pseudotype-based neutralization assays against nine SARS-CoV-2 variants and anti-S1 IgG ELISA were employed.

Main Results:

• Antibody levels peaked after the third mRNA vaccine dose (Comirnaty) and remained stable for two years.
• Neutralization titers increased significantly after the second and third doses, with the highest levels observed two years post-booster.
• Hybrid immunity demonstrated higher neutralization titers at the final time point compared to vaccination alone.
• Moderate correlations were observed between anti-S1 IgG and neutralization titers against Omicron subvariants, with the lowest neutralization against the XBB variant.

Conclusions:

• Booster vaccinations are important for maintaining robust antibody levels and protection against SARS-CoV-2.
• Hybrid immunity provides more durable and potent long-term protection compared to vaccination alone.
• Emerging SARS-CoV-2 variants like XBB exhibit significant immune evasion, necessitating ongoing surveillance and vaccine updates.