China is implementing a de facto quarantine of unprecedented scale: about 20 million people in Wuhan and two other large cities nearby. Is quarantine effective? What are some of issues raised by large-scale quarantine during infectious disease outbreaks?
Quarantine restricts movement of people who may be at risk of disease, to help control spread. Some in a quarantined group are not infected, some may be infected. Quarantine can be contrasted with isolation, which is separating infected people from those not infected.
In the U.S., at least, no large-scale quarantine has been implemented in over 100 years (last used during the 1918 influenza pandemic).
In modern times, quarantine is used to control fast-moving outbreaks for which there is no treatment or cure, like SARS and the new coronavirus, where Infection control, isolation, quarantine, and other “non-pharmaceutical interventions” may be the only options to slow spread.
During SARS, countries implemented quarantines, differing in approach, scope, and strictness. A common approach was “stay at-home” quarantines of those potentially exposed to SARS because they were health workers, family members, or other close contacts (i.e. air passengers).
In Taiwan, contacts of SARS cases and passengers arriving from SARS affected areas were quarantined for 10-14 days. People weren’t allowed to leave homes/the clinic, with meals provided for them. Police guarded doors in many cases. cdc.gov/mmwr/preview/m…
In all, 130,000 people were quarantined for SARS in Taiwan Mar-Jul 2003. This was labor-intensive and costly. Among the quarantined, 131 (0.1%) later developed SARS. Being in quarantine instead of out in the community meant they did not cause further spread of the disease.
A broader review of public health measures during the SARS outbreak found quarantine of contacts to be one of the key interventions that helped stop the disease. ncbi.nlm.nih.gov/pmc/articles/P…
For its part, the WHO found the evidence on home quarantine for SARS was effective, and supported countries’ use of this approach who.int/csr/sars/en/WH….
Quarantine was also used during the Ebola response of 2014-2015. All 3 highly affected countries in West Africa implemented quarantines of contacts, households, and even whole geographic areas. At one point, a third of the population of Sierra Leone was locked down for 3 days.
While quarantine of contacts and high-risk households was likely helpful in interrupting Ebola transmission, the effectiveness of large-scale geographic quarantines is more questionable, and they came at a high societal cost. ncbi.nlm.nih.gov/pmc/articles/P…
In the U.S., the CDC instituted entry screening of those traveling from Ebola affected areas, but recommended against mandatory quarantines. States had discretion to impose quarantines, thought, and some imposed 21-day mandatory quarantines.
Of course, what’s happening in China is of a different scale than quarantines for SARS and Ebola. The number of people being quarantined is unprecedented, and it is a much more blunt approach than quarantining contacts or those at high-risk.
Studies find under some conditions quarantine can be good option, where: 1) disease spreads in a community even with isolation of cases; 2) transmission without symptoms occurs, and; 3) individuals are quarantined in a timely fashion ncbi.nlm.nih.gov/pubmed/16421244
Quarantine can only work when effectively enforced. If there is “leakage” i.e. enough people get around the restrictions, then effectiveness is reduced. Enforcement requires a lot of manpower and logistics, especially at the scale being attempted in Wuhan.
There is a balance between the political and social costs of quarantine and public health benefit. Quarantine of a whole city is a major imposition with many potential collateral costs, and may even bring more public health problems than it is trying to solve.
Businesses and families must be ensured adequate access to food, supplies, medicines, social services and other supports.
Without knowing more about the characteristics of the new coronavirus and the disease it causes, it is hard say whether a quarantine of this magnitude is advisable and the benefits outweigh the costs. A information comes out, this will be focus for public health policymakers.
