Abstract
Approximately half of the SARS-CoV-2 infections occur without apparent symptoms, raising questions regarding long-term humoral immunity in asymptomatic individuals. Plasma levels of immunoglobulin G (IgG) and M (IgM) against the viral spike or nucleoprotein were determined for 25,091 individuals enrolled in a surveillance program in Wuhan, China. We compared 405 asymptomatic individuals who mounted a detectable antibody response with 459 symptomatic COVID-19 patients. The well-defined duration of the SARS-CoV-2 endemic in Wuhan allowed a side-by-side comparison of antibody responses following symptomatic and asymptomatic infections without subsequent antigen re-exposure. IgM responses rapidly declined in both groups. However, both the prevalence and durability of IgG responses and neutralizing capacities correlated positively with symptoms. Regardless of sex, age, and body weight, asymptomatic individuals lost their SARS-CoV-2-specific IgG antibodies more often and rapidly than symptomatic patients did. These findings have important implications for immunity and favour immunization programs including individuals after asymptomatic infections.
Highlights
The world faces a global COVID-19 pandemic
Previous virus proteome-wide analyses showed that asymptomatic infections mainly produce Immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies recognizing the S1 or the N protein of SARS-CoV-2 [8]
At least to our knowledge, the first comprehensive side-by-side comparison of asymptomatically infected individuals and symptomatic COVID-19 patients in the long-term aftermath of a SARS-CoV-2 endemic
Summary
The world faces a global COVID-19 pandemic. As of August 9, 2021, more than 202.7 million people had a laboratory-confirmed SARS-CoV-2 infection and nearly 4.2 million people died during or in the direct aftermath of COVID-19 [1]. An important determinant for the number of unrecorded cases is the occurrence of very mild and/or asymptomatic infections, which are the focus of this study. The scarcity of Humoral Immunity in Asymptomatic Individuals secondary SARS-CoV-2 infections [2, 3] indicates that adaptive immune responses prevent re-infections in the vast majority of cases - at least during the approximately one-year period during which SARS-CoV-2 has been studied to date. Others and we have shown that binding and neutralizing antibodies develop rapidly after infection and are maintained in the majority of symptomatic COVID-19 patients for a period of 6-10 months after disease onset [4,5,6]. We felt that the duration of protective immunity in asymptomatic individuals should be elucidated in larger cohorts and with a more informative study design
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