Changes in serum-neutralizing antibody potency and breadth post-SARS-CoV-2 mRNA vaccine boost

Area of Science:

• Immunology
• Virology
• Vaccinology

Background:

• Understanding antibody response to COVID-19 vaccines is vital.
• Durability and breadth of neutralizing antibodies against SARS-CoV-2 variants are key.

Purpose of the Study:

• Quantify the decay of serum neutralizing antibodies (nAbs) after primary and booster COVID-19 mRNA vaccination.
• Assess antibody durability and breadth against SARS-CoV-2 variants and other sarbecoviruses.

Main Methods:

• Utilized an authentic virus-neutralization assay.
• Measured decay half-lives of nAbs against WA1, Delta, and Omicron (BA.1.1, BA.5, BA.2.12.1) subvariants.
• Evaluated antibody response broadening after a booster dose.

Main Results:

• WA1 and Delta nAb decay half-lives were approximately 60 days after two or three vaccine doses.
• Antibodies neutralizing Omicron subvariants showed significantly better durability (≥6 months half-life).
• Booster dose broadened antibody responses against SARS-CoV, other sarbecoviruses, and SARS-CoV-2 strains.

Conclusions:

• COVID-19 mRNA vaccines elicit durable neutralizing antibody responses, particularly against Omicron subvariants.
• Booster doses enhance antibody breadth, potentially offering cross-protection against related sarbecoviruses.
• Repeated vaccination may mitigate risks associated with future zoonotic spillover events.