  COVID-19 is now a global pandemic, and an effective vaccine may be many
months away. Over 100 years ago, Spanish flu fatalities were attenuated when
doctors began treating patients with blood plasma donated by recovered (or
convalesced) survivors. Passive immunity transfer via administration of
convalesced blood product (CBP) appears to represent a readily available and
promising avenue for mitigating mortalities, expediting recovery time, and even
prophylaxis against the SARS-CoV-2 virus. Here, we review challenges to CBP
efficacy, and present a graph theoretical model of transmission dynamics that
identifies evolving hubs of COVID-19 cases. Importantly, this model suggests
that CBP efficacy may rest on an efficient and distributed global sampling
scheme as opposed to CBP pooled from local donors alone.
