For the 17 completed contact investigations, interval I was the largest interval in the contact tracing procedure (mean 2,6 days, range 1-6, 95% CI 1,6-3,6, n = 13). The other intervals II and III were shorter, with a mean of 0,8 days and 0,6 days respectively, see Table 1 . Figure 3 shows the medians of the described intervals. Since 15/ 17 index cases were already ill before, or during the day of arrival of the flight, the delay in interval I is mainly caused by delay in seeking medical advice and diagnostic procedure itself. After acceptance of the request for CT by the CIb, GGD Kennemerland needed on average 0,6 days (range 0-2, 95% CI 0,3-0,9 days) to collect the passenger list from the airlines and complete contact details (interval III). The total delay between flight arrival and identification of contact details was on average 3,9 days (range 2-7 days, 95% confidence interval 3,2-4,7 days), see Table 1 . In only 3 out of 17 contact investigations (18%), contacts were identified within 2 days after arrival. In 2 out of these 3 contact investigations, PLC's were available. Interval III of the 5 CT with PLC's available was shorter (0,4 days, SD 0,5) than for 12 CT's without PLC (0,7 days, SD 0,7), this was not significant however (p: 0,25). Overall delay in CT with PLC's also was shorter (mean 3,6, SD 1,8), but not significant, when compared to CT without PLC's (mean 4,1, SD 1,4) (p:0,25).