Sustainability of SARS-CoV-2 Induced Humoral Immune Responses in COVID-19 Patients from Hospitalization to Convalescence Over Six Months

Abstract

Understanding the persistence of antibody in convalescent COVID-19 patients may help to answer the current major concerns such as the risk of reinfection, the protection period of vaccination and the possibility of building an active herd immunity. This retrospective cohort study included 172 COVID-19 patients who were hospitalized in Wuhan. A total of 404 serum samples were obtained over six months from hospitalization to convalescence. Antibodies in the specimens were quantitatively analyzed by the capture chemiluminescence immunoassays (CLIA). All patients were positive for the anti-SARS-CoV-2 IgM/IgG at the onset of COVID-19 symptoms, and the IgG antibody persisted in all the patients during the convalescence. However, only approximately 25% of patients can detect the IgM antibodies, IgM against N protein (N-IgM) and receptor binding domain of S protein (RBD-IgM) at the 27th week. The titers of IgM, N-IgM and RBD-IgM reduced to 16.7%, 17.6% and 15.2% of their peak values respectively. In contrast, the titers of IgG, N-IgG and RBD-IgG peaked at 4-5th week and reduced to 85.9%, 62.6% and 87.2% of their peak values respectively at the end of observation. Dynamic behavior of antibodies and their correlation in age, gender and severity groups were investigated. In general, the COVID-19 antibody was sustained at high levels for over six months in most of the convalescent patients. Only a few patients with antibody reducing to an undetectable level which needs further attention. The humoral immune response against SARS-CoV-2 infection in COVID-19 patients exhibits a typical dynamic of acquired immunity. Yang Zheng and Qing Zhang contributed equally to this work.

Over 1‐year duration and age difference of SARS‐CoV‐2 antibodies in convalescent COVID‐19 patients

“…A previous study showed that SARS‐CoV‐2 IgM peaked in the 2nd week after the onset of symptoms, and then decreased until disappeared in the 16th week after the onset of symptoms. 24 In this study, we reported that the SARS‐CoV‐2 IgM persisted positive in 12.80% convalescent COVID‐19 patients after recovery for 1 year. Not only in our study, Chuanmiao Liu and colleagues reported that 22.7% of convalescent patients still persisted as IgM antibody positive after 6 months of recovery.…”

SARS-CoV-2 antibodies remain detectable 12 months after infection and antibody magnitude is associated with age and COVID-19 severity

“…However, the development of detectable humoral immunity is likely a predictive surrogate of protection 1,2 . The presence of broadly neutralizing serum antibodies five to eight months after SARS-CoV-2 infection have been documented by several groups [3][4][5][6][7][8][9][10] . Cases of symptomatic COVID-19 following re-infection with SARS-CoV-2 have been reported but are infrequent [11][12][13][14][15] , and recent studies have highlighted a correlation between the presence of SARS-CoV-2 antibodies and decreased risk of reinfections 16,17 .…”

Antibody Responses in COVID-19: A Review

“…However, there are also several reports that point to the opposite conclusion. There is compelling evidence on the persistence of robust neutralizing antibodies for months after infection, as well as favorable antibody kinetic profiles in large national studies, which range from five to eight months (72,73,91,92). To assess said establishment of a durable protection, Lumley et al studied antibody responses in healthcare workers and followed up 1265 seropositive subjects (93).…”