Implications of all the available evidence
Evidence supports the quarantine of individuals who have had close contact with confirmed or highly suspected cases. Quarantine of individuals traveling from countries with a confirmed outbreak reduces further spreading; however, is a less effective measure with substantially fewer cases and deaths averted than quarantine of individuals who have had close contact with cases. Implementing quarantine as early as possible seems to be key to control an outbreak.

1 Introduction

Coronavirus disease 2019 (COVID-19) is a new, rapidly emerging zoonotic infectious disease.1 Since the first reported case from Wuhan (Hubei province, China) on December 31, 2019, the number of confirmed cases has risen to more than 105 500 in more than 100 countries as of March 8, 2020. On January 30, 2020 the World Health Organization (WHO) declared the outbreak a global health emergency.2
COVID-19 is caused by a novel coronavirus, SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) which is transmitted via droplets and fomites during close unprotected contact with an infector.1 Health care setting transmissions play an important role in the spread of the disease.3 The virus is genetically similar to the coronaviruses that caused Severe Acute Respiratory Syndrome (SARS) and the Middle East Respiratory Syndrome (MERS), but SARS-CoV-2 appears to have greater transmissibility and lower pathogenicity than the aforementioned viruses. Preliminary estimates of the basic reproduction number (R0) of SARS-CoV-2, as a metric for transmissibility, range from 2·8 to 5·5, in the absence of intense quarantine and social distancing measures.4 In comparison, R0 for SARS was estimated at 3·0,5 and at < 1·0 for MERS in most regions.6 The average R0 for seasonal influenza viruses is about 1·8.7
The pathogenicity of SARS-CoV-2 apears to be substantially lower than that of SARS and MERS. The majority (81%) of symptomatic COVID-19 patients develop a mild form of the disease with dry cough, fever, or unspecific symptoms such as headache, myalgias, or fatigue. More severe cases suffer from dyspnea and pneumonia, and about 5·0-6·0% of COVID-19 patients are critcally ill with respiratory failure, sepsis, or multi-organ failure.1,8 The case-fatality rate (CFR) for COVID-19 was high at the beginning of the outbreak in Wuhan but has declined over time to 0·7% for patients with symptom onset after February 1,1 which is substantially lower than CFR for SARS (9·6%) and MERS (34·4%), but higher than that for seasonal influenza pandemics (0·01%).9-11
Currently, no effective interventions or vaccines are available to treat or prevent COVID-19. For this reason, public health measures such as isolation, social distancing, and quarantine are the only effective ways to respond to the outbreak. Isolation refers to the separation of symptomatic patients whereas quarantine is the restriction of asymptomatic healthy people who have had contact with confirmed or suspected cases. Quarantine can be implemented on a voluntary basis or can be legally enforced by authorities and may be applied at an individual, group, or community level (community containment).12 A recent rapid review reported that quarantine can have negative psychological effects such as post-traumatic stress symptoms, confusion, and anger which can lead to adverse long-term psychological effects.13 At this time, WHO and the US Center for Diasease Control and Prevention (CDC) recommend 14 days of quarantine for individuals who were in close contact with a confirmed case, based on the estimated incubation period of SARS-CoV-2.14,15
According to the International Health Regulations (2005)16 that govern the management of disease outbreaks in 196 countries, any public health measures must be based on scientific evidence and recommendations from WHO.17 To support WHO for their recommendations on quarantine, we conducted a rapid review on the effectiveness of quarantine during serious coronavirus outbreaks. Our work was guided by the following key questions (KQs). Figure 1 depicts the analytic framework.