is quarantine an effective measure to prevent spread?

Deserted streets, the sound of loudspeakers intimating orders to stay cloistered at home, supermarket shelves emptying … On the Internet, the inhabitants of Wuhan, epicenter of the spread of the 2019-nCoV virus, have started to document in videos the largest collective quarantine operation ever implemented, with more than 40 million inhabitants concerned. A containment measure inherited from a long tradition of health risk management, but the effectiveness of which is widely debated.

• A practice dating back to the XIV^e century

If the oldest occurrence of confinement of patients dates back to an episode of leprosy in the Old Testament, it is to protect themselves from the black plague that appear in the XIV^e and XV^e centuries the first documented measures to isolate ships from infected areas. The first operation of its kind was observed in Dubrovnik (Croatia) in 1377, then in Venice (Italy) from 1423. The imposed duration of the isolation – thirty, then forty days – is at the origin of the word ” quarantine “.

The establishments which accommodate the confined crews are then baptized “lazarets”: deformation of the name of the islet in the Venetian lagoon where the ships docked, Santa Maria di Nazareth, or else reference to Lazarus of the Bible, patron saint of lepers. Genoa, Marseilles, etc., the largest ports in Europe are equipped with such establishments to isolate populations from infected areas.

At the same time, the practice of the “sanitary cordon” is also developing, to control and block entry or exit from an area affected by an epidemic. In 1665, the small British village of Eyam thus decided to isolate itself from the rest of the world after a case of plague, to avoid contaminating the rest of the region. In the south-east of France, a “plague wall” was erected in the Vaucluse in 1721 over 27 kilometers to protect the Comtat Venaissin region from the plague which then raged in Marseille and Provence.

To implement these measures, the state does not hesitate to use force. In 1821, Paris sent 30,000 soldiers to block the border with Spain in order to prevent the spread of an epidemic of yellow fever.

• Relative efficiency, far from being the “absolute weapon”

Mechanically, movement restrictions have an immediate impact on the spread of the epidemic. But its effectiveness depends on the speed of the authorities to set it up, underlines thus Patrick Zylberman, health historian and emeritus professor at the School of advanced studies in public health, questioned by Point : “It can, for example, delay and decrease the height of the contamination peak, and thus reduce mortality. But do not mythologize the quarantine, think that it is the absolute weapon with magic powers. “

In some cases, movement restriction measures can even be counterproductive. By indiscriminately mixing asymptomatic but contagious patients and healthy people, the measurement can thus accelerate the transmission of the virus within the confined area.

In addition, the measurement can cause panic and thus increase the risk of contamination. This was the case in 2014 when parts of Liberia’s capital, Monrovia, were quarantined to stem the Ebola outbreak. Clashes had occurred between the frightened population and the soldiers, leading to the death of several civilians. The measure had also increased distrust of medical personnel, causing some patients to hide their symptoms to avoid confinement.

• A measure more political than health

In the past, some quarantines have also led to social unrest, in particular due to the economic deadlock they cause. This was the case in 2003, when the SARS epidemic in China led to riots and violent demonstrations in the regions of Nanjing and Shanghai following brutal confinements, providing no assistance to the populations concerned, in particular for the food supply or medical care.

More recently, during the Ebola epidemic in West Africa (2013-2016), border closure, containment and quarantine measures were repeatedly imposed. Thus, the six million Sierra Leoneans were forced to stay at home for three days in September 2014, then again in March 2015. This is “ one form among others of quarantine with almost zero effectiveness, but the government must show that it is doing something “, commented Patrick Zylberman.

• Is collective quarantine possible in France?

Officially, a decree authorizes the French prefects to declare containment zones in the event of a health threat. But the measure has never been implemented. In 1955, Vannes, in Morbihan, had almost been concerned when an epidemic of smallpox was raging there. But compulsory vaccination had been decreed and 70% of the city’s population had been vaccinated in six days, avoiding quarantine.

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