Coronavirus (COVID-19) Collection
Epidemiological assessment of SARS-CoV-2 reinfection
COVID-19 began as an outbreak in Wuhan, China, in December 2019 and was declared a pandemic by the World Health Organization (WHO) in March 2020 (WHO, 2020). The disease, caused by SARS-CoV-2, has affected >271,900,000 people worldwide and led to >5,000,000 deaths as of December 19, 2021 (WHO, 2021c). There are currently five SARS-CoV-2 variants that are classified as variants of concern: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and more recently, Omicron (B.1.1.529) (WHO, 2021b).The potential significance of high avidity immunoglobulin G (IgG) for protective immunity towards SARS-CoV-2
The avidity of immunoglobulin G (IgG) is determined by its affinity and denotes the strength of binding to its target epitope. High avidity is reached after affinity/avidity maturation and reflects the best fit between IgG and epitope. Avidity of IgG is low during acute infection and reaches high values several weeks or months later (Hedman et al., 1997; Bauer, 2021). Memory B cells express and utilize high avidity IgG to establish effective anamnestic responses (Eisen, 2014).
