Antibody persistency and trend post-SARS-CoV-2 infection at eight months.

Introduction: A large amount of recent research has focused on the nature of immunity elicited by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, particularly its robustness and the duration of protection it offers. As a vaccine's efficacy relies on its ability to induce a protective immune response, these questions remain particularly pertinent. An improved understanding of the immunity offered by the antibodies developed against SARS-CoV-2 in recovered patients is critical for the development of diagnostic tests and vaccines. Methods: Our study aimed at the longitudinal analysis of antibody presence, persistence and its trend over eight months in a group of 30 COVID-19 recovered patients who tested positive by real-time quantitative PCR for SARS-CoV-2 in the period 1-30 March 2020. The subjects were divided into two groups based on disease severity: mild (n=17 subjects) and moderately-severe (n=13 subjects). The MAGLUMI 2019-nCoV lgM/lgG chemiluminescent analytical system (CLIA) assay was used to analyze these antibody titres. Results: IgG antibody persistency was demonstrated in 76.7 % of the subjects (23 out of 30) at eight months post-infection. For the moderately-severe group, the titre trends for both IgM and IgG changed in a statistically significant way throughout the time period with IgM below and IgG above the set cut-off. Conclusions: The results of this study highlight an important point in terms of the association between humoral immune response and disease severity. Patients who have experienced a relatively severe infection might develop a stronger immune response that could persist for a longer period.

Neutralizing antibody responses against SARS-CoV-2 spike receptor-binding domain 13 months after the recovery from the disease.

BACKGROUND: Information regarding the kinetics and longevity of acquired immunity in recovered COVID-19 patients requires thorough analysis and documentation. This is an update to an ongoing monocentric pilot observational study, that longitudinally analyzed the presence of antibodies after SARS-CoV-2 infection. STUDY DESIGN: Antibody titers against nucleocapsid protein (NCP) of SARS-CoV-2 analyzed at 8 months was followed by adoption of a more specific immunoassay, anti-Spike-Receptor binding domain IgG CLIA for analysis at 12 and 13 months post infection. METHODS: MAGLUMI® SARS-CoV-2 S-RBD IgG Chemiluminescence immunoassay (CLIA) was adopted for measurement of antibody titres at 12 and 13 months after SARS-CoV-2 infection. RESULTS: 97% (34 out of 35) patients resulted positive for anti-SARS-CoV-2 RBD IgG at 12 and 13 months. DISCUSSION AND CONCLUSIONS: In areas with vaccine and resource scarcity, vaccination could be prioritized for those individuals who have never been infected or for the ones who have recovered but show the absence of protective antibodies.