Abstract
Background: There is much data available concerning the initiation of the immune response after SARS-CoV-2 infection, but long-term data are scarce. Methods: We thus longitudinally evaluated and compared the total and neutralizing immune response of 61 patients to SARS-CoV-2 infection up to eight months after diagnosis by RT–PCR using several commercial assays. Results: Among the 208 samples tested, the percentage of seropositivity was comparable between assays up to four months after diagnosis and then tended to be more heterogeneous between assays (p < 0.05). The percentage of patients with a neutralizing titer decreased from 82% before two months postdiagnosis to 57% after six months. This decrease appeared to be more marked for patients under 65 years old and those not requiring hospitalization. The percentage of serology reversion at 6 months was from 11% with the WANTAI total assay to over 39% with the ABBOTT IgG assay. The neutralizing antibody titers decreased in parallel with the decrease of total antibody titers, with important heterogeneity between assays. Conclusions: In conclusion, serological tests show equivalent sensitivity in the first months after the diagnosis of SARS-CoV-2 infection, but their performance later, postinfection, must be considered when interpreting the results.
Highlights
COVID-19, defined as the disease caused by the new SARS-CoV-2 coronavirus, has caused more than two million deaths worldwide, and more than 100 million cases have been detected by RT-PCR
61 patients, representing 208 samples diagnosed with SARS-CoV-2 infection by RT–PCR between March and April 2020, were screened for the study
We found similar profiles, demonstrating a difference between the assays for the evaluation of seropositivity towards SARS-CoV-2 distant from infection, as well as a progressive decrease in neutralizing titers
Summary
COVID-19, defined as the disease caused by the new SARS-CoV-2 coronavirus, has caused more than two million deaths worldwide, and more than 100 million cases have been detected by RT-PCR. After infection by the virus, an immune response directed against these proteins is rapidly established during the first two weeks following infection, making it possible, in most cases, to effectively control the infection. The detection of this immune response by in-house or commercial serological assays is indicative of a previous infection by SARS-CoV-2. Methods: We longitudinally evaluated and compared the total and neutralizing immune response of 61 patients to SARS-CoV-2 infection up to eight months after diagnosis by RT–PCR using several commercial assays. The percentage of serology reversion at 6 months was from
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