While initially it was felt that droplet transmission was most the likely mode, recommendations have been upgraded to airborne and contact transmission, since the natural course of this infection is still not completely understood, infectivity or contagiousness seems higher than SARS, and people seem to be able to transmit infection before they ever become symptomatic, and for some days after seemingly full recovery (https://www.cdc.gov/coronavirus/2019-ncov/about/transmission.html) (Figs. 3 4 , 3a 5 , 6 , 4a 7 ).