SARS-CoV-2 antibody progression and neutralizing potential in mild symptomatic COVID-19 patients - a comparative long term post-infection study

BackgroundSince December 2019, SARS-CoV-2 has been keeping the world in suspense. Rapid tests, molecular diagnosis of acute infections, and vaccination campaigns with vaccines are building blocks of strategic pandemic control worldwide. For laboratory diagnostics, the quantification of the antibody titer of convalescents and vaccinated patients is thus increasingly coming to the fore. MethodsHere we present an evaluation on the comparability of five serological tests on a cohort of 13 patients with mild COVID-19 disease. Also participants who were vaccinated after recovery were included in this study. All common immune methods (ELISA, CLIA, PETIA) and SARS-CoV-2 specific antigens (N-, S1- and RBD-) were specifically tracked and directly compared for up to 455 days. The titer of recovered participants was also set to the degree of symptoms during infection and the occurrence of Long-COVID. In addition, relative comparability of different serological tests, all standardized to WHO, was set in reference to the neutralizing potential of the corresponding participants. FindingsThe individual immune responses over 455 days after a mild SARS-CoV-2 infection remain stable, in contrast to vaccinated participants. All sero-tests reveal comparable performance and dynamics during the study and compared well to a surrogate neutralization test. ConclusionThe information presented here will help clinicians in the daily laboratory work in the selection and evaluation of different serological tests offered. The data also will support in respect of a sero-test-based neutralization cutoff.

Automated summary

This study compared five serological tests on a cohort of 13 patients with mild COVID-19 disease. The results showed that individual immune responses remained stable over 455 days after a mild SARS-CoV-2 infection, while vaccinated participants showed different responses. All serological tests performed comparably and were well compared to a surrogate neutralization test. The information presented will assist clinicians in selecting and evaluating different serological tests in their daily laboratory work.