Entry screening to delay local transmission of 2009 pandemic influenza A (H1N1).
BACKGROUND
After the WHO issued the global alert for 2009 pandemic influenza A (H1N1), many national health agencies began to screen travelers on entry in airports, ports and border crossings to try to delay local transmission.


METHODS
We reviewed entry screening policies adopted by different nations and ascertained dates of official report of the first laboratory-confirmed imported H1N1 case and the first laboratory-confirmed untraceable or 'local' H1N1 case.


RESULTS
Implementation of entry screening policies was associated with on average additional 7-12 day delays in local transmission compared to nations that did not implement entry screening, with lower bounds of 95% confidence intervals consistent with no additional delays and upper bounds extending to 20-30 day additional delays.


CONCLUSIONS
Entry screening may lead to short-term delays in local transmission of a novel strain of influenza virus. The resources required for implementation should be balanced against the expected benefits of entry screening.
Cowling
Benjamin J
BJ
School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China. bcowling@hku.hk
Lau
Lincoln L H
LL
Wu
Peng
P
Wong
Helen W C
HW
Fang
Vicky J
VJ
Riley
Steven
S
Nishiura
Hiroshi
H
D003140:Communicable Disease Control / Q000379:methods*; D004196:Disease Outbreaks / Q000517:prevention & control; D006291:Health Policy; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology*; D008403:Mass Screening / Q000379:methods*; D013997:Time Factors; D014195:Travel