Immunoglobulin G antibody immune response profile following infection with SARS-CoV-2 in COVID-19 Egyptian patients.

This study aimed to report the dynamic profile of IgG-specific antibodies to SARS-CoV-2 infection for 6 months after infection. We conducted a prospective study, recruited 33 recently confirmed covid -19 patients and collected 6 samples from each patient. The first samples were collected one month from the start of symptoms and subsequent samples collected at 30 days interval. We measured the IgG by chemiluminescent immunoassay (CLIA). According to the disease severity, patients were categorized as asymptomatic 4 (12.1%), mild 14 (42,4%), moderate 9 (27.3%), and severe 6 (18.2%). Patients were 12 (35.3%) females and 21 (64.7%) males. The mean IgG levels maintained a high level till the second month (92.81 ± 110.15 AU/ml) from the onset of symptoms followed by a gradual decrease till the sixth month after infection (17.42 ± 22.61 AU/ml). The patients with severe symptoms significantly exhibited the highest IgG levels, reached the highest level (mean=237.44 ± 164.13 AU/ml) at the second month. While the lowest levels were detected among the asymptomatic patients (mean= 3.04 ± 2.94 AU/ml) at the second month. Older age correlated with higher IgG antibody level (r= 0.350 p=0.046); however, sex was not related to IgG level. In conclusion, Symptomatic COVID-19 disease is followed by protective immunity for more than 6 months. Immunity in asymptomatic patients is low and fades rapidly than symptomatic cases. Patients with severe disease had significantly higher IgG levels compared to mild, moderate, or asymptomatic patients.