Relationship between Antibody Levels and SARS-Cov-2 Reinfection

Area of Science:

• Immunology
• Infectious Diseases
• Virology

Background:

• Emerging SARS-CoV-2 variants necessitate understanding humoral immunity's protective role.
• Limited data exists on the efficacy of antibodies against Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) reinfection.

Purpose of the Study:

• To investigate COVID-19 antibody levels and their correlation with SARS-CoV-2 reinfection.
• To determine the protective antibody threshold against reinfection.

Main Methods:

• Retrospective analysis of 1665 patients positive for COVID-19 IgG antibodies.
• Tracking of COVID-19 reverse transcription polymerase chain reaction (RT-PCR) test positivity from a national database.
• Recording of patient demographics, comorbidities, and prior RT-PCR results.

Main Results:

• A reinfection rate of 0.8% was observed among the studied cohort.
• Reinfection was significantly more frequent in patients with a negative RT-PCR test (p<0.001).
• An IgG cut-off value of 11.9 was identified as protective against reinfection (AUC: 0.844).

Conclusions:

• Humoral antibodies generated by SARS-CoV-2 infection provide a degree of protection against reinfection.
• Asymptomatic individuals with negative RT-PCR tests showed a higher frequency of reinfection.
• The study identified a specific IgG antibody level associated with reduced reinfection risk.