Abstract
Background: A potentially important aspect of the humoral immune response to Covid-19 is avidity, the overall binding strength between antibody and antigen. As low avidity is associated with a risk of re- infection in several viral infections, avidity might be of value to predict risk for reinfection with covid-19.
Objectives: The purpose of this study was to describe the maturation of IgG avidity and the antibody-levels over time in patients with PCR-confirmed non-severe covid-19.
Study design: Prospective longitudinal cohort study including patients with RT-PCR confirmed covid-19. Blood samples were drawn 1, 3 and 6 months after infection. Antibody levels and IgG-avidity were analysed.
Results: The majority had detectable s- and n-antibodies (88,1%, 89,1%, N = 75). The level of total n-antibodies significantly increased from 1 to 3 months (median value 28,3 vs 39,3 s/co, p<0.001) and significantly decreased from 3 to 6 months (median value 39,3 vs 17,1 s/co, p<0.001). A significant decrease in the IgG anti-spike levels (median value 37,6, 24,1 and 18,2 RU/ml, p<0.001) as well as a significant increase in the IgG-avidity index (median values 51,6, 66,0 and 71,0%, p<0.001) were seen from 1 to 3 to 6 months.
Conclusion: We found a significant ongoing increase in avidity maturation after Covid-19 whilst the levels of antibodies were declining, suggesting a possible aspect of long-term immunity.
Keywords: Anti-nucleocapsid; Anti-spike; Antibody; Avidity; Covid-19; SARS-CoV-2.
【저자키워드】 COVID-19, SARS-CoV-2, antibody, avidity, Anti-nucleocapsid, Anti-spike, 【초록키워드】 SARS-CoV-2, IgG, severe COVID-19, Immunity, antibody, Infection, risk, RT-PCR, viral infections, Antigen, Reinfection, Viral, Prospective, Patient, antibody levels, humoral immune response, avidity, predict, Anti-spike, antibody level, binding, PCR-confirmed, maturation, Blood samples, significant increase, longitudinal cohort study, blood sample, significant decrease, median values, median value, levels of antibodies, significantly increased, significantly, detectable, analysed, median, majority, increase in, declining, levels of antibody, 【제목키워드】 Dynamics,