Neutralizing antibody responses to SARS-CoV-2: A population based seroepidemiological analysis.

Area of Science:

• Immunology
• Virology
• Public Health

Background:

• Understanding SARS-CoV-2 antibody response is crucial for managing the pandemic.
• Serological markers like IgG and neutralizing antibodies indicate past infection and immunity.
• Assessing the correlation between these markers provides insights into population-level protection.

Purpose of the Study:

• To estimate the seroprevalence of SARS-CoV-2 neutralizing antibodies in Delhi's general population.
• To correlate the levels of neutralizing antibodies with anti-SARS-CoV-2 IgG antibody levels.
• To evaluate the reliability of IgG levels as a proxy for neutralizing capacity.

Main Methods:

• Simple random sampling was used to select participants from Delhi.
• A surrogate virus neutralization test (sVNT) was performed to detect neutralizing antibodies.
• Anti-SARS-CoV-2 IgG levels were measured and correlated with sVNT results.

Main Results:

• Out of 2564 IgG seropositive samples, 2233 (87.1%) showed detectable neutralizing antibodies.
• In samples with a Signal-to-Cutoff (S/CO) ratio ≥ 4.00, neutralizing antibody prevalence ranged from 94.5% to 100%.
• A strong positive correlation (r=0.62, p=0.002) was observed between neutralizing antibody seroprevalence and IgG S/CO range.

Conclusions:

• A high proportion of SARS-CoV-2 IgG seropositive individuals in Delhi possess neutralizing antibodies.
• IgG antibody levels show a significant correlation with the presence of neutralizing antibodies, suggesting their utility in assessing immunity.
• These findings contribute to understanding humoral immunity against SARS-CoV-2 in a large urban population.