Fig. A.1.

Estimated infected and deaths using profile travel.

The Estimated infected plot shows the ratio of confirmed cases to estimated infected in each county on $T_1=$ March 13. $T_0$ is February 23rd. We use the full European Entry. Estimated infected are given by the reported on $T_1+Lag$ and divided by $\alpha$. We use an eight-day lag.

The second plot shows the ratio of cohort-matched confirmed deaths to estimated infected in each county on Mar 13th, taking into account an 8 day lag in reporting. We use the full European Entry. We estimate fatality-lag time as a log-normal distribution with mean 14.5 and standard deviation 6.7. Estimated infected are computed for each daily cohort using the National-$\alpha$ of 4.09%. We omit New York City for visual clarity.