Nationwide Cohort to Estimate Burden of Respiratory Viruses and Immunologic Response (Blood Donor Cohort)

and surveys to monitor the burden of infection, risk factors for infection, and explore the duration and extend of immunity by population throughout the US (2020-2022).  By 2022, algorithms for using quantitative antibody titers to detect reinfection were established and tested, creating novel systems for monitoring burden even in the setting of high overall seroprevalence.Adapting these tools to the current context, this research cooperative agreement would establish a large-scale longitudinal cohort (>50,000 persons) of repeat blood donors with the purpose of: 1) estimating the national burden of incident SARS-CoV-2 infection, and further adapting the approach to other respiratory viruses as technology allows including Respiratory Syncytial Virus, Influenza, Human Metapneumovirus, EVD-68, and others; 2) determining antibody thresholds for protection across multiple respiratory viruses; 3) assessing state- or region-specific population-level immunity to/risk for infection through tracking median antibody titers within various populations; and 4) monitoring waning immunity and changes in immune capabilities in the context of ongoing viral evolution.