Page 145 - Timeliness of Infectious Disease Notification & Response Systems - Corien Swaan

Timeliness of contact tracing among flight passengers 143
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).
Discussion and conclusions
In this study we evaluated the timeliness of contact tracing (CT) of flight con- tacts in daily practice. We conclude that the prevailing policy to provide close contacts antiviral PEP during the early phase of the influenza pandemic is very difficult to implement effectively and therefore has little effect to control di- sease spread. Active case finding through contact tracing of exposed persons is an important procedure during the containment phase of an emerging com- municable disease. However, our data show that, even in a small-industrialized country with modern communication tools, tracing of flight contacts exceeds the required maximum of 48 h after exposure.
For influenza, close contacts of contagious index cases are entitled to re- ceive antiviral PEP within 48 h after exposure to prevent them from becoming ill and further spreading of the disease. Starting oseltamivir within 48 h does not prevent disease but shortens the disease period, mitigates symptoms and might decrease further transmission. Awareness among contacts to seek me- dical evaluation when influenza-like (ILI) symptoms occur, for both proper an- tiviral treatment and (home-) isolation advice, reduces further spreading. As influenza has a relative short latent period, for influenza A(H1N1)/2009 varying between 0.7- 3.1 days [16,17], contacts ideally should be informed within 1 day. Oseltamivir postexposure prophylaxis for this pandemic strain is reported to be effective even when administrated more than 48 h after exposure in household settings [18], however, delays in administration are not specified. We cannot exclude the possibility that in our study, even delayed administration of oselta- mivir prophylaxis may have prevented some people from becoming ill, although we anticipate the effectiveness of the intervention overall to be less in this set- ting than in households.
Our study among 17 contact investigations showed an average total delay of 3.9 days between flight arrival and identification of contacts by passenger list, which is too late for effective PEP, and late for alerting on first symptoms of di- sease. Only in three contact investigations (18%), contact details were obtained within 48 h. However, after identification of passenger details, health authori- ties need time to actually trace the contact and administer PEP. It is highly un- likely that this was achieved within the same 48 h. We therefore conclude that contact investigation for provision of PEP as conducted here was ineffective.
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