BRD2 and infection: Compared with the strategies of (a) no NAT, (b) NAT within 14 days before travelling would reduce the number of active infections on the day of travel by 28.1% (95% CI: 25.1, 31.1); (c) NAT within 10 days before travelling would reduce the number by 39.5% (95% CI: 36.2, 42.7); (d) NAT within 7 days before travelling would reduce the number by 57.4% (95% CI: 54.1, 60.7); (e) NAT within 5 days before travelling would reduce the number by 74.8% (95% CI: 71.5, 78.0); and (f) NAT within 3 days before travelling would reduce the number by 84.2% (95% CI: 81.8, 86.7) (Figure 1 and Figure S3).