Containing an emerging bird flu pandemic at its source will probably only delay – not stop – the illness’ spread because of likely multiple introductions of the pathogen, assert researchers from the Harvard School of Public Health (HSPH) and the University of Washington in a policy paper in PLoS Medicine. The paper will appear in the open access journal online on Feb. 20 after 8 p.m.

“If a single introduction of a pandemic-capable strain is likely to happen, then multiple introductions are also likely,” said HSPH Associate Professor of Epidemiology Marc Lipsitch. “If there are multiple introductions, then there are numerous chances for containment, and the strategy only has to fail once to result in a pandemic.”

Containment describes attempts to reach a pandemic source as early as possible and then apply public health tools such as vaccination (if available), antiviral drugs, and quarantine to curb a pathogen’s spread. Containment is one component of federal and World Health Organization planning for a possible flu pandemic.

The researchers argue that resources would be strained with each new effort at containment, making subsequent control strategies more and more difficult to implement. Under good circumstances, containment efforts may only double the time before a pandemic emerges, the researchers have calculated. That time could drop even further if efforts underpinning the containment, such as surveillance for human cases, are inadequate.