Concern for potential bioterrorist attacks causing mass casualties has
increased recently. Particular attention has been paid to scenarios in which
a biological agent capable of person-to-person transmission, such as smallpox,
is intentionally released among civilians. Multiple public health interventions
are possible to effect disease containment in this context. One disease control
measure that has been regularly proposed in various settings is the imposition
of large-scale or geographic quarantine on the potentially exposed population.
Although large-scale quarantine has not been implemented in recent US history,
it has been used on a small scale in biological hoaxes, and it has been invoked
in federally sponsored bioterrorism exercises. This article reviews the scientific
principles that are relevant to the likely effectiveness of quarantine, the
logistic barriers to its implementation, legal issues that a large-scale quarantine
raises, and possible adverse consequences that might result from quarantine
action. Imposition of large-scale quarantine—compulsory sequestration
of groups of possibly exposed persons or human confinement within certain
geographic areas to prevent spread of contagious disease—should not
be considered a primary public health strategy in most imaginable circumstances.
In the majority of contexts, other less extreme public health actions are
likely to be more effective and create fewer unintended adverse consequences
than quarantine. Actions and areas for future research, policy development,
and response planning efforts are provided.