As COVID-19 rages on worldwide, there is an urgent need to characterize immune correlates of protection from SARS-CoV-2 infection and to identify immune determinants of COVID-19 severity.
We present longitudinal profiles of neutralizing antibody titers in hospitalized COVID-19 patients clinically diagnosed with mild symptoms, pneumonia, and severe pneumonia up to 12 months after illness onset, using live-virus neutralization. Multiplex, correlation, and network analyses were used to characterize serum-derived inflammatory cytokine profiles in all severity groups.
Peak NAb titers correlated with disease severity, and NAb titers declined over the course of 12 months regardless of severity. Multiplex analyses revealed that IP-10, IL-6, IL-7, and VEGF-α were significantly elevated in severe pneumonia cases compared to mild symptoms and pneumonia cases. Correlation and network analyses further suggested that cytokine network formation was distinct in different COVID-19 severity groups.
Our findings inform on the long-term kinetics of naturally acquired serological immunity against SARS-CoV-2 and highlight the importance of identifying key cytokine networks for potential therapeutic immunomodulation.

Copyright © 2021. Published by Elsevier Ltd.