International health regulations: lessons from the influenza pandemic in Singapore.
BACKGROUND
Singapore's defense against imported novel influenza A (H1N1-2009) comprised public health measures in compliance with the World Health Organization's (WHO) International Health Regulations (IHR), 2005. We report herein on the epidemiology and control of the fi rst 350 cases notified between May and June 2009.


METHODS
We investigated the fi rst 350 laboratory-confirmed cases of novel influenza A (H1N1-2009) identified from the healthcare institutions between 27 May and 25 June 2009. Epidemiological details of these cases were retrieved and analysed. Contact tracing and active case finding were also instituted for each reported case, and relevant particulars including flight information were provided to WHO and overseas counterparts.


RESULTS
The fi rst 350 novel influenza A (H1N1-2009) cases comprised 221(63%) imported cases, 124 (35%) locally acquired cases and 5 (2%) cases with unknown source. The imported cases consisted of three waves involving the United States (US), Australia and Southeast Asia. In the fi rst wave, 11 (69%) of the 16 imported cases had visited the US within seven days prior to their onset of illness between 25 May and 4 June 2009. In the second wave, 20 (74%) of the 27 imported cases between 5 June and 12 June had travelled to Melbourne, Australia. In the third wave, 90 (51%) of the 178 imported cases between 13 June and 25 June were acquired from intra-regional travel in Southeast Asia. Specifically, 49 cases were from the Philippines and 40 (82%) of them had travelled to Manila. A total of 667 communications were effected through the IHR mechanism; a majority within 24 hours of disease notification.


CONCLUSIONS
Singapore experienced an unprecedented need for international cooperation in surveillance and response to this novel Influenza A (H1N1-2009) pandemic. The IHR mechanism served as a useful channel to engage in regional cooperation concerning disease surveillance and data sharing, but requires improvement.
Low
Chew Ling
CL
Communicable Disease Division, Ministry of Health, Singapore.
Chan
Pei Pei
PP
Cutter
Jeffery L
JL
Foong
Bok Huay
BH
James
Lyn
L
Ooi
Peng Lim
PL
D000293:Adolescent; D000328:Adult; D002648:Child; D018563:Disease Notification; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D007391:International Cooperation; D008297:Male; D012846:Singapore / Q000453:epidemiology; D014195:Travel; D014944:World Health Organization; D055815:Young Adult