Serological Surveillance of COVID-19 Hospitalized Patients in Réunion Island (France) Revealed that Specific Immunoglobulin G Are Rapidly Vanishing in Severe Cases

Abstract

Humoral immunity is critically important to control COVID-19. Long-term antibody responses remain to be fully characterized in hospitalized patients who have a high risk of death. We compared specific Immunoglobulin responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between two groups, intensive care unit (ICU) and non-ICU hospitalized patients over several weeks. Plasma specific IgG, IgM, and IgA levels were assessed using a commercial ELISA and compared to an in-house cell-based ELISA. Among the patients analyzed (mean (SD) of age, 64.4 (15.9) years, 19.2% female), 12 (46.2%) were hospitalized in ICU. IgG levels increased in non-ICU cases from the second to the eighth week after symptom onset. By contrast, IgG response was blunted in ICU patients over the same period. ICU patients with hematological malignancies had very weak or even undetectable IgG levels. While both groups had comparable levels of specific IgM antibodies, we found much lower levels of specific IgA in ICU versus non-ICU patients. In conclusion, COVID-19 ICU patients may be at risk of reinfection as their specific IgG response is declining in a matter of weeks. Antibody neutralizing assays and studies on specific cellular immunity will have to be performed.

High seroprevalence of SARS-CoV-2 but low infection fatality ratio eight months after introduction in Nairobi, Kenya

“…This study had several limitations. A few studies have reported loss of SARS-CoV-2 antibodies in previously seropositive individuals, perhaps associated with a weak immunologic response or low infecting viral load(Dobi et al, 2020). While we used a validated total antibody test kit, asymptomatic and mild cases that occur more commonly in younger individuals have been shown to evoke lower titers of antibodies which may be missed by EIA tests, such as that used in this study.…”

Low levels of the key B cell activation marker, HLA-DR, in COVID-19 hospitalized cases are associated with disease severity, dexamethasone treatment, and circulating IL-6 levels

“…According to the World Health Organization (WHO), more than 219 million COVID-19 cases and over 4.5 million deaths have been reported worldwide, at the beginning of September 2021. Clinical data showed that 10–15% of hospitalized infected patients progress to severe complications [ 1 ].…”