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Low Levels of Protective Humoral Immunity Following Mild or Asymptomatic Infection With SARS-Cov-2 in a Community-Based Serological Study (WP-21-21)

Thomas McDade, Amelia Sancilio, Richard D’Aquila, Brian Mustanski, Lauren Vaught, Nina Reiser, Matthew Velez, Ryan Hsieh, Daniel Ryan, Rana Saber, Elizabeth McNally, and Alexis Demonbreun

The degree of protective humoral immunity after mild or asymptomatic SARS-CoV-2 infection is not known. The researchers measured antibody-mediated neutralization of spike protein-ACE2 receptor binding—a surrogate measure of protection against SARS-CoV-2 infection—in a large and diverse community-based seroprevalence study. Comparisons were made across three groups of seropositive participants that differed in the severity of infection and engagement with clinical care (N=790). The clinical group was seropositive for prior infection, symptomatic, and diagnosed with COVID-19 by a healthcare provider. The symptomatic group was seropositive and reported one or more symptoms of infection but received no clinical care. The asymptomatic group was seropositive but reported no symptoms. 86.2% of all infections were mild or asymptomatic; 13.8% received clinical care. Of the clinical cases, 96.3% were outpatient; only 3.7% required hospitalization. Moderate or high levels of neutralizing activity were detected following 27.5% of clinical infections, in comparison with 5.4% of symptomatic and 1.5% of asymptomatic infections. The majority of infections in the general population are mild or asymptomatic and likely result in low levels of antibody-mediated protective immunity.

Thomas McDade, Carlos Montezuma Professor of Anthropology and IPR Fellow, Northwestern University

Amelia Sancilio, Postdoctoral Fellow, IPR, Northwestern University

Richard D’Aquila, Howard Taylor Ricketts, MD, Professor of Medicine, Northwestern University

Brian Mustanski, Professor of Medical Social Sciences and IPR Associate, Northwestern University

Lauren Vaught, Center for Genetic Medicine, Northwestern University

Nina Reiser, Center for Genetic Medicine, Northwestern University

Matthew Velez, Center for Genetic Medicine, Northwestern University

Ryan Hsieh, Center for Genetic Medicine, Northwestern University

Daniel Ryan, Institute for Sexual and Gender Minority Health and Wellbeing, Northwestern University

Rana Saber, Institute for Sexual and Gender Minority Health and Wellbeing, Northwestern University

Elizabeth McNally, Elizabeth J. Ward Professor of Genetic Medicine, Northwestern University

Alexis Demonbreun, Assistant Professor of Pharmacology, Northwestern University

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