  This paper proposes a structural econometric approach to estimating the basic
reproduction number ($\mathcal{R}_{0}$) of Covid-19. This approach identifies
$\mathcal{R}_{0}$ in a panel regression model by filtering out the effects of
mitigating factors on disease diffusion and is easy to implement. We apply the
method to data from 48 contiguous U.S. states and a diverse set of countries.
Our results reveal a notable concentration of $\mathcal{R}_{0}$ estimates with
an average value of 4.5. Through a counterfactual analysis, we highlight a
significant underestimation of the $\mathcal{R}_{0}$ when mitigating factors
are not appropriately accounted for.
