Figure 4
Shared Ride Time Histogram \(\tau _{ij}\) and Network of Close Contacts (CCs). (a) We show the weight distribution \(\tau _{ij}\) of the network of Potentially Infectious Contacts (PICs) in 15-minute-width bins. The average of the shared ride times of PICs is \(\langle \tau _{ij}\rangle ^{PICs} \approx 28\) min. Applying the threshold \(\tau _c=15\) min in the network of PICs, we define a network of Close Contacts (CCs). For the network of CCs, the average of the shared ride times is \(\langle \tau _{ij}\rangle ^{CCs} \approx 39\) min. The inset shows the Complementary Cumulative Distribution Function (CCDF) of \(\tau _{ij}\). We find that the percentage of the edges with \(\tau _{ij}\) greater than \(\tau _c=15\) min is \(\approx 62 \%\) (dashed line), i.e., most part of PICs are CCs. (b) The vertices represent the bus passengers that were diagnosed with COVID-19 and the edges corresponds to the CCs each passenger had using the public transportation system in Fortaleza. The healthcare and non-healthcare workers are represented by red and gray vertices, respectively. The size of the vertices is proportional to their outdegrees.
