Improving the estimation of the COVID-19 effective reproduction number using nowcasting

As the interactions between people increases, the impending menace of COVID-19 outbreaks materializes, and there is
an inclination to apply lockdowns. In this context, it is essential to have easy-to-use indicators for people to employ as a
reference. The effective reproduction number of confirmed positives, Rt, fulfills such a role. This document proposes a
data-driven approach to nowcast Rt based on previous observations’ statistical behavior. As more information arrives,
the method naturally becomes more precise about the final count of confirmed positives. Our method’s strength is that
it is based on the self-reported onset of symptoms, in contrast to other methods that use the daily report’s count to
infer this quantity. We show that our approach may be the foundation for determining useful epidemy tracking
indicators