Figure 3.

Asymptomatic and symptomatic SARS-CoV-2 infection in Vietnam. A, Distribution of the interval between entry into the country and the onset of symptoms for 92 symptomatic imported SARS-CoV-2 positive cases, differentiating those who were isolated at entry from those who were not. Symptoms occurred after entry on the right-hand side of the vertical red line. B, Duration of hospital stay of 208 discharged SARS-CoV-2 positive cases. Dots and error bars show mean and 95% confidence interval (assuming a gamma distribution) per decile of age, lines and shaded areas show gamma regression fits and their 95% confidence intervals. Corresponding gamma regression table is in Table S2. C, Relationship between age and the proportion asymptomatic among 208 discharged SARS-CoV-2 positive cases. Vertical dotted lines indicate deciles of the age distribution, with the proportion asymptomatic estimated within each of these deciles. Vertical error bars show 95% confidence intervals. Horizontal line and the gray area show the average across ages and its 95% confidence interval. Corresponding logistic regression table is in Table S3. D, Distribution of serial intervals for 33 infector-infectee pairs together with a normal distribution fitted to it. The shaded area shows the 95% confidence interval. The vertical black line shows the estimate of the mean serial interval, together with its 95% confidence interval (dashed vertical lines). The proportion of the distribution to the left of the red line is a proxy for the proportion of infections that occur before the onset of symptoms. Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.