Detection, prevalence, and duration of humoral responses to SARS-CoV-2 under conditions of limited population exposure

Abstract

We conducted an extensive serological study to quantify population-level exposure and define correlates of immunity against SARS-CoV-2. We found that relative to mild COVID-19 cases, individuals with severe disease exhibited elevated authentic virus-neutralizing titers and antibody levels against nucleocapsid (N) and the receptor binding domain (RBD) and the S2 region of spike protein. Unlike disease severity, age and sex played lesser roles in serological responses. All cases, including asymptomatic individuals, seroconverted by 2 weeks post-PCR confirmation. RBD- and S2-specific and neutralizing antibody titers remained elevated and stable for at least 2-3 months post-onset, whereas those against N were more variable with rapid declines in many samples. Testing of 5882 self-recruited members of the local community demonstrated that 1.24% of individuals showed antibody reactivity to RBD. However, 18% (13/73) of these putative seropositive samples failed to neutralize authentic SARS-CoV-2 virus. Each of the neutralizing, but only 1 of the non-neutralizing samples, also displayed potent reactivity to S2. Thus, inclusion of multiple independent assays markedly improved the accuracy of antibody tests in low seroprevalence communities and revealed differences in antibody kinetics depending on the viral antigen. In contrast to other reports, we conclude that immunity is durable for at least several months after SARS-CoV-2 infection.

Humoral Responses and Serological Assays in SARS-CoV-2 Infections

“…Such observations are also supported by a number of additional studies that also measured a decline of IgG antibodies after several weeks PSO (44,131). However, most groups have demonstrated that IgG levels against SARS-CoV-2 remained relatively stable within a 3 to 5 month observation period PSO (43,124,(130)(131)(132)(133)(134)(135).…”

Assessing the age specificity of infection fatality rates for COVID-19: systematic review, meta-analysis, and public policy implications

“…Symptoms typically develop within 6 days after exposure but may develop as early as 2 days or as late as 14 days [1,33]. More than 95% of symptomatic COVID patients have positive antibody (IgG) titres within 17-19 days of symptom onset, and those antibodies remain elevated over a sustained period [34][35][36][37]. The mean time interval from symptom onset to death is 15 days for ages 18-64 and 12 days for ages 65 + , with interquartile ranges of 9-24 days and 7-19 days, respectively, while the mean interval from date of death to the reporting of that person's death is about 7 days with an IQR of 2-19 days; thus, the upper bound of the 95% confidence interval between symptom onset and reporting of fatalities is about 6 weeks (41 days) [38].…”

Differential kinetics of T cell and antibody responses delineate dominant T cell epitopes in long-term immunity after COVID-19

“…So far, data on long-term immunity to SARS-CoV-2 are lacking. Available reports, up to three months after COVID-19 are partially con icting, but overall point towards a decrease and even loss of SARS-CoV-2-speci c antibody responses (4)(5)(6)(7)(8) and thus raise concerns regarding longterm humoral immunity. In SARS-CoV-1, T cell immunity was identi ed as important determinant for recovery and long-term protection (9-12), with long-lasting memory T cell responses detected in convalescents even 17 years after infection (13).…”