The COVID-19 pandemic, which emerged at the end of 2019, may have receded from public consciousness, but its impact continues to reverberate. Over the past three years, countries worldwide have grappled with multiple waves of widespread infection. Although many nations have now established immunity barriers, the risk of long COVID symptoms and recurrent infections still looms large. Such repeated infections could have a profound effect on individuals' immune function.

A research team conducted a year-long follow-up study, scrutinizing the antibody response of COVID-19 patients and analyzing the correlation between antibody response and neutralizing antibody activity. Recently, published in the Frontiers in Immunology journal as "Evaluation of Humoral Immune Response in Relation to COVID-19 Severity Over 1 Year Post-Infection: Critical Cases Show a Higher Humoral Immune Response Than Mild Cases," this study sheds light on the long-term dynamics of SARS-CoV-2-specific B cell memory in recovered COVID-19 patients.

Monitoring antibody levels in individuals who have recovered from COVID-19 or received vaccinations is crucial. The research team employed various methods to achieve this goal. They used the recombinant protein of the SARS-CoV-2 spike S1 domain as an antigen and employed the indirect enzyme-linked immunosorbent assay (ELISA) to detect IgG antibodies in COVID-19 patients.

ELISA, a plate-based assay technique, facilitates the detection and quantification of peptides, proteins, and hormones. It relies on specific antigen-antibody binding and utilizes enzymes. In ELISA, an antigen (or antibody) is immobilized on a solid surface, followed by the addition of enzyme-conjugated antibodies after incubation with specific antibodies (or antigens). Detection involves evaluating conjugated enzyme activity through incubation with a substrate to yield a quantifiable result.

The team also utilized indirect immunofluorescence (IIF) by infecting Vero E6 cells with SARS-CoV-2 samples obtained from the Korea Centers for Disease Control and Prevention. IIF is a two-step serological technique used to identify circulating autoantibodies in a patient's serum. This method involves a primary, unlabeled antibody binding to the target, followed by a fluorophore-labeled secondary antibody to detect the primary antibody. Although more complex and time-consuming, IIF is more sensitive due to the ability of more than one secondary antibody to bind to each primary antibody, thus amplifying the fluorescence signal.

By observing the distribution and localization of specific antibodies within cells and tissues, IIF provides valuable insights into the effectiveness of the immune response. Using ELISA and IF in tandem aids in the development of targeted and personalized treatment strategies for post-COVID care.

In the pursuit of more effective COVID-19 management, human anti-SARS-CoV-2 spike recombinant antibody (CR3022 antibody) therapy emerges as a promising development. By targeting the spike protein of the virus, CR3022 can neutralize SARS-CoV-2 and potentially inhibit viral infection. Incorporating CR3022 antibody therapy into post-COVID care, along with the monitoring provided by ELISA and IF, may offer heightened protection, especially for high-risk individuals and those with compromised immune systems.

In addition to CR3022 antibody, other anti-SARS-CoV-2 RBD antibodies such as mouse anti-SARS-CoV-2 recombinant antibody also have been developed against novel coronavirus. Alongside antibody-focused strategies, maintaining essential public health measures such as mask-wearing, social distancing, and vaccination remains critical to curbing the virus's spread and preventing new variants.