Abstract
Background: The diagnosis of SARS-CoV-2 is almost exclusively performed by PCR or antigen detection. The detection of specific antibodies has not yet been considered in official diagnostic guidelines as major laboratory evidence for a case definition. The aim the present study is to analyze antibody responses in outpatient and inpatient cohorts of COVID-19 patients in the Czech Republic over a 12-month period, and assess the potential of antibodies as a diagnostic tool. Methods: A total of 644 patients was enrolled in the prospective study. IgA, IgM and IgG antibody levels, as well as virus neutralization titers, were analyzed over a 12-month period. Results: Our study showed low antibody positivity levels at the admission. However, at 2 weeks after infection, 98.75% and 95.00% of hospitalized patients were IgA and IgG positive, respectively. Even in the outpatient cohort characterized by milder disease courses, the IgG antibody response was still sustained at 9 and 12 months. The data show a high correlation between the IgG levels and virus neutralization titers (VNTs). Samples from later time-points showed positive antibody responses after vaccination in both cohorts characterized by high IgG levels and VNT over 1:640. The samples from unvaccinated persons indicated a relatively high level of reinfection at 6.87%. Conclusions: Our results show that the detection of antibodies against the SARS-CoV-2 shows an increasing sensitivity from week 2 after infection and remains highly positive over the 12-month period. The levels of IgG antibodies correlate significantly with the VNTs. This suggests that the serological data may be a valuable tool in the diagnosis of SARS-CoV-2 infection.
Highlights
A suspected case definition of this disease was characterized by a combination of clinical and epidemiological criteria both in the Center for Disease Control and Prevention (CDC) and World Health Organization (WHO) guidelines
The aims of this study are (a) to provide a long-term analysis of antibody responses in large COVID-19 in- and outpatient cohorts from the Central European region for the first time; (b) provide support for the notion that specific antibodies can be used as proof of the ongoing or passed disease, for the situations in which a direct identification of the virus is negative; (c) show a correlation between virus neutralization titers (VNTs) and specific antibody levels, which can be used as predictors of the antibody neutralization capacity; and (d) confirm the efficacy of the vaccination
The results show that, in cohort A, 56.10% of the were tested for their neutralization capacity, in parallel with the Ig levels, using the original samples showed VNTs over 1:40 and only 21.46% generated neutralization titers of 1:160 variant of live SARS-CoV-2 virus
Summary
The virus named SARS-CoV-2 subsequently caused infections in more than 172 million people, which led to more than. The laboratory confirmation was made by the detection of SARS-CoV-2 nucleic acid using PCR or the positivity of SARS-CoV-2-specific antigen according to the WHO guidelines. The CDC guidelines, accept a supportive role of the serological detection of specific antibodies for the diagnosis of SARS-CoV-2 infection [2,3]. The diagnosis of SARS-CoV-2 is almost exclusively performed by PCR or antigen detection. The detection of specific antibodies has not yet been considered in official diagnostic guidelines as major laboratory evidence for a case definition. The aim the present study is to analyze antibody responses in outpatient and inpatient cohorts of COVID-19 patients in the Czech. IgA, IgM and IgG antibody levels, as well as virus neutralization titers, were analyzed over a 12-month period.
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