Quarantine involves identifying people who are at risk of being infected with contagious disease, such as those who have recently traveled or are showing symptoms but are not yet infected (not ill), and then physically segregating them from others for a defined period of time that is designed to exceed the incubation period for the illness. Historically, quarantine was a common health intervention, particularly during episodes of disease pandemics, but has fallen out of favor in recent years as public health practice has become more sophisticated and better informed.
The primary reason for the resurgence of interest in quarantine is the emergence of new communicable diseases that have shown the ability to spread quickly, challenging community defenses and exposing gaps in preparedness (e.g., SARS and avian influenza). Quarantine can be an important part of a holistic approach to communicable disease control that includes public health communication, containment, and other controls.
However, questions remain about how and when to implement quarantine and about what factors contribute to its effectiveness and to any potential harms. The committee’s primary question was whether under what circumstances quarantine is effective in curbing the transmission of infectious disease through person-to-person contact, and it also sought evidence on a series of subquestions relating to specific adherence strategies, documented benefits and harms, and factors that promote or hinder implementation of quarantine measures.