  In this article we present hygiea, an end-to-end blockchain-based solution
for the Covid-19 pandemic. hygiea has two main objectives. The first is to
allow governments to issue Covid-19 related certificates to citizens that can
be verified by designated verifiers to ensure safer workplaces. The second is
to provide the necessary tools to experts and decision makers to better
understand the impact of the pandemic through statistical models built on top
of the data collected by the platform. This work covers all steps of the
certificate issuance, verification and revocation cycles with well-defined
roles for all stakeholders. We also propose a governance model that is
implemented via smart contracts ensuring security, transparency and
auditability. Finally, we propose techniques for deriving statistical models
that can be used by decision makers.
