Neutralizing antibody titres in SARS-CoV-2 infections

Area of Science:

• Immunology
• Virology
• Public Health

Background:

• The SARS-CoV-2 pandemic presents a significant global health crisis.
• Understanding the kinetics of virus neutralizing antibody responses is crucial for assessing protection.
• Neutralizing antibodies are recognized as a key correlate of protection against SARS-CoV-2.

Purpose of the Study:

• To investigate the durability and kinetics of neutralizing antibody responses following SARS-CoV-2 infection.
• To compare antibody responses across different disease severities (severe, mild, asymptomatic).
• To assess the impact of age on neutralizing antibody levels.

Main Methods:

• Analysis of 293 sera from 195 RT-PCR confirmed SARS-CoV-2 infections.
• Plaque reduction neutralization (PRNT) assays were performed on sera collected 0-209 days post-symptom onset.
• Estimation of antibody half-life (T1/2) and time to reach detection limit for PRNT50 titres.

Main Results:

• 99.1% of individuals with sera collected ≥61 days post-onset remained seropositive for neutralizing antibodies (PRNT90 and PRNT50).
• Estimated time for PRNT50 titres to reach 1:10 varied by severity: 372 days (severe), 416 days (mild), 133 days (asymptomatic).
• Individuals with severe disease exhibited higher peak neutralizing antibody titres compared to mild or asymptomatic cases. Age did not significantly impact antibody responses.

Conclusions:

• SARS-CoV-2 infection induces robust and durable neutralizing antibody responses in the majority of individuals.
• Antibody decay rates differ based on disease severity, with slower decline in milder cases.
• The findings suggest a strong, long-term protective immune response following natural SARS-CoV-2 infection.