Quarantine

Quarantine is the separation and restriction of movement of individuals who have been exposed to a contagious disease but are not yet ill, in order to monitor for the development of symptoms and prevent potential transmission. It differs from isolation, which applies to people who are already ill and may be contagious.

Historically, quarantine has appeared in various forms since ancient times. The term comes from the Italian quaranta giorni, meaning forty days, the length of time ships were isolated during plague outbreaks in the medieval period. Ports established lazarettos and formal regulations to separate arrivals from the broader population.

Modern quarantine practices involve assessing exposure risk, setting a defined duration, and monitoring health status. Exposed people may be asked to stay at home or in designated facilities, avoid contact with others, and report symptoms or test results. Duration depends on the disease and public health guidance.

Quarantine is a public health power that may be exercised by government agencies, often with voluntary compliance and, in some cases, legal compulsion. Ethical considerations include proportionality, transparency, least restrictive means, and provisions for essential needs and due process.

Effectiveness depends on timely identification of exposure, adherence to restrictions, and the pathogen’s characteristics. Quarantine is less effective for asymptomatic or pre-symptomatic infections and can entail social and economic costs. It is typically used together with testing, contact tracing, and vaccination efforts.

Internationally, the World Health Organization’s International Health Regulations guide cross-border quarantine measures, and many countries maintain border screening, travel advisories, and airport or port quarantines during outbreaks. Quarantine also applies to animal and product imports to prevent the introduction of diseases.