Early epidemic growth curves. (A) Costa Rica, (B) Panamá, (C) Uruguay, (D) USA, Costa Rica and Singapore (y-axis is in log scale, and the first day on the x-axis is when cases approached 40, which in Costa Rica was day 10 after the first case detection). In panels A, B and C curves are based on maximum likelihood parameter estimates, inset in each panel with their 95% confidence intervals, for the early epidemic growth model of equation (4). In panel (D) data from Singapore and the USA were obtained from coronavirus.jhu.edu/data.