Abstract
Durability of SARS-CoV-2 Spike antibody responses after infection provides information relevant to understanding protection against COVID-19 in humans. We report the results of a sequential evaluation of anti-SARS-CoV-2 antibodies in convalescent patients with a median follow-up of 14 months (range 12.4-15.4) post first symptom onset. We report persistence of antibodies for all four specificities tested [Spike, Spike Receptor Binding Domain (Spike-RBD), Nucleocapsid, Nucleocapsid RNA Binding Domain (N-RBD)]. Anti-Spike antibodies persist better than anti-Nucleocapsid antibodies. The durability analysis supports a bi-phasic antibody decay with longer half-lives of antibodies after 6 months and antibody persistence for up to 14 months. Patients infected with the Wuhan (WA1) strain maintained strong cross-reactive recognition of Alpha and Delta Spike-RBD but significantly reduced binding to Beta and Mu Spike-RBD. Sixty percent of convalescent patients with detectable WA1-specific NAb also showed strong neutralization of the Delta variant, the prevalent strain of the present pandemic. These data show that convalescent patients maintain functional antibody responses for more than one year after infection, suggesting a strong long-lasting response after symptomatic disease that may offer a prolonged protection against re-infection. One patient from this cohort showed strong increase of both Spike and Nucleocapsid antibodies at 14 months post-infection indicating SARS-CoV-2 re-exposure. These antibodies showed stronger cross-reactivity to a panel of Spike-RBD including Beta, Delta and Mu and neutralization of a panel of Spike variants including Beta and Gamma. This patient provides an example of strong anti-Spike recall immunity able to control infection at an asymptomatic level. Together, the antibodies from SARS-CoV-2 convalescent patients persist over 14 months and continue to maintain cross-reactivity to the current variants of concern and show strong functional properties.
Highlights
Understanding the longevity of antibody responses against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) is important because it will allow to compare and to contrast infection-induced and vaccination-induced immune responses
We have reported on a sequential analysis of SARS-CoV-2 antibody responses in COVID-19 convalescent patients over a period of 8 months post symptom onset [1, 2]
The study design allowed for the measurements and the sequential evaluation of anti-SARS-CoV-2 antibodies against Spike and Nucleocapsid collected longitudinally over 14 months post symptom onset
Summary
Understanding the longevity of antibody responses against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) is important because it will allow to compare and to contrast infection-induced and vaccination-induced immune responses. We have reported on a sequential analysis of SARS-CoV-2 antibody responses in COVID-19 convalescent patients over a period of 8 months post symptom onset [1, 2]. We previously reported a bi-phasic decline with an inflection point at 6 months post symptom onset [1]. The shorter half-lives of Spike and Nucleocapsid antibodies during the first 6 months post symptom onset were followed by longer half-lives for both specificities thereafter. In our 8-month follow-up, we reported that 76% of the patients still had detectable Neutralizing Antibodies (NAb) [1]. Many studies reported short-term follow-up observations of less than 6 months [3–15], whereas others reported longitudinal observations, typically spanning less than 12 months post symptom onset [1, 4, 16–27]. Some studies reported contraction of anti-COVID humoral responses with a stronger initial decline [1, 4, 23–25, 27]
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