Immune responses associated with protection from SARS-CoV-2 infection

Area of Science:

• Immunology
• Virology
• Vaccinology

Background:

• Immune correlates of protection against SARS-CoV-2 remain debated.
• Bivalent mRNA boosters are used to enhance immunity against SARS-CoV-2 variants.

Purpose of the Study:

• To investigate the association between humoral and cellular immune responses after bivalent mRNA booster vaccination and subsequent SARS-CoV-2 infection.
• To identify specific immune correlates of protection against symptomatic and asymptomatic SARS-CoV-2 infection.

Main Methods:

• Secondary analysis of a randomized trial comparing immediate versus delayed bivalent mRNA booster vaccination.
• Measurement of neutralizing antibodies, plasma antibody titers, and B and T cell responses to Spike antigen 28 days post-vaccination.
• Statistical analysis to determine the correlation between immune responses and subsequent SARS-CoV-2 infection.

Main Results:

• Neutralizing antibodies and plasma antibody titers were correlated with protection against SARS-CoV-2 infection.
• In multivariate analysis, only neutralizing antibodies remained significantly associated with protection (p=0.021).
• No significant correlation was found between B and T cell responses and protection from infection.

Conclusions:

• Neutralizing antibodies are a key correlate of protection against SARS-CoV-2 infection after bivalent mRNA booster vaccination.
• Cellular immune responses (B and T cells) did not show a significant association with protection in this study.
• Findings reinforce the importance of antibody-mediated immunity in preventing COVID-19.