Fig. 4.

The relationship between cumulative border policy duration, the number of total arrivals and COVID-19 incidence. Density plots of the tourist volume in four categories countries that applied each policy the longest. Size of the circle represented the quantity of confirmed COVID-19 cases and the vertical line marked the median of total arrivals (a); Coefficients of cumulative border policy duration predicting total arrivals (b); Scatter plot by combining coefficient estimates of border policy duration predicting total arrivals and COVID-19 infections (c). Solid and hollow shapes represented univariate and multivariate regression estimates respectively. See full regression results in Supplementary Table S14‒17.