Tuesday, August 14, 2007

Pandemic Preparedness and Non-Pharmaceutical Interventions

The public health folks at Effect Measure do their usual good job as they analyze a study (subscription only) in the Journal of the American Medical Association (JAMA), which Time also covered.

The JAMA study examined the effectiveness of various non-pharmaceutical interventions (NPIs) in mitigating the spread of the 1918 Spanish Flu pandemic. For local communities, examining such a study is useful in light of the fact that the CDC's interim Community Flu Planning Guide emphasizes the early, layered, targeted use of non-pharmaceutical interventions (also see this post).

In examining the JAMA study, Effect Measure finds:

They classified the non pharmaceutical interventions (NPIs) into three broad categories: school closures; bans on public gatherings; isolation and quarantine and looked at timing and timeliness as well as combinations of NPI categories for effects on excess mortality, height of epidemic peak and timing of epidemic peak, using multivariate analysis.

What is quite clear from the analysis ... is that information about when, how long and in what combination NPIs were used in relation to the onset of the epidemic in a city explains a great deal of the variation in epidemic experience.

The analysis showed that combinations were more effective than single interventions.
Short answer: Layered interventions work.
The bottom line is that the earlier a city acts and the more coordinated and multifaceted its response the better off it seemed to be -- in general. The data certainly do not demonstrate that quarantine itself is effective -- they are not able to make that statement. Cities that acted using isolation and quarantine did seem to do better, especially if in combination with other measures, but we don't know the effectiveness of either separately or in combination since they were not reported or analyzed separately in the paper.

What these data do seem to establish is that the better prepared and organized a community is, the better off it will be. And the more a community ignores and denies a problem, the worse off it will be. This is the real message, not that "quarantines work."
There is nothing surprising in learning that preparation is critical for an effective, coordinated response. It's always good to review empirical data, however.

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