SARS-CoV-2 infection induces sustained humoral immune responses in convalescent patients following symptomatic COVID-19

Abstract

Long-term antibody responses and neutralizing activities in response to SARS-CoV-2 infection are not yet clear. Here we quantify immunoglobulin M (IgM) and G (IgG) antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) of the spike (S) or the nucleocapsid (N) protein, and neutralizing antibodies during a period of 6 months from COVID-19 disease onset in 349 symptomatic COVID-19 patients who were among the first be infected world-wide. The positivity rate and magnitude of IgM-S and IgG-N responses increase rapidly. High levels of IgM-S/N and IgG-S/N at 2-3 weeks after disease onset are associated with virus control and IgG-S titers correlate closely with the capacity to neutralize SARS-CoV-2. Although specific IgM-S/N become undetectable 12 weeks after disease onset in most patients, IgG-S/N titers have an intermediate contraction phase, but stabilize at relatively high levels over the 6 month observation period. At late time points, the positivity rates for binding and neutralizing SARS-CoV-2-specific antibodies are still >70%. These data indicate sustained humoral immunity in recovered patients who had symptomatic COVID-19, suggesting prolonged immunity.

Longitudinal changes in IgG levels among COVID-19 recovered patients: A prospective cohort study

“…Monitoring IgG response is an important aspect of understanding the scope of immunity development. There have been previous reports about the persistence of IgG against COVID-19 virus in particular [ 2 , 5 , 7 – 9 ]. However, the interpretation of such reported studies poses some limitations due to their retrospective nature, short duration, small sample size and lack of repeated quantitative estimation of IgG response.…”

“…A recent study from Iceland showed the possibilities of a continued antibody response post COVID-19 infections for at least a period of four months [ 9 ]. A study [ 2 ] in Wuhan has investigated the IgG and IgM response in COVID-19 patients for a period of 26 weeks. The study showed IgG positivity rate at about 70% at 6 months follow up period.Another study among 87 American found a decrease in IgG level and memory B cell response consistent with antigen persistence, with a 6 months follow-up [ 17 ].…”

“…Antibody response is one of the key factors for development of immunity and preventing re-infection. In general, following infection, the body’s immune system blocks the viral entry with neutralizing natural antibodies [ 2 – 5 ]. During SARS-CoV2 viral infection, the fusion process of the virus with the host cell membranes is facilitated by two spike (S) glycoproteins S1 and S2 [ 6 ].…”

“…As the vaccination against COVID-19 is under development and is not yet available for wide use, there is an increasing interest in investigating the persistence of antibody response against COVID-19 virus [ 2 , 5 , 7 – 11 ]. The humoral response a few weeks after SARS-CoV-2 infection has been thoroughly described, some studies reported stable antibody levels within the first three months of recovery, whereas others showed a rapid decrease in convalescent patients [ 12 – 16 ].…”

Seroconversion and dynamics of the anti-SARS-CoV-2 antibody response related to a hospital COVID-19 outbreak among pediatric oncology patients

“…As was mentioned above, adult acute leukemia patients were capable of developing neutralizing anti-SARS-CoV-2 antibodies [ 2 ]. In our study, the majority of patients demonstrated the presence of anti-spike (anti-RBD) antibodies, which titers appear to closely correlate with the neutralizing capacity [ 4 ]. Moreover, a recent meta-analysis has demonstrated that pediatric patients with COVID-19 suffering from hematological neoplasia or solid tumors were not at an increased risk of unfavorable outcomes [ 5 ].…”