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.
- KQ 1: For contacts of a confirmed COVID-19 case, is quarantine
effective in reducing the onward transmission of SARS-CoV-2
infections?
- KQ1a: Are there differences in the effectiveness of quarantine in
different settings?
- KQ 2: In repatriated individuals coming from a country with a declared
COVID-19 outbreak, is quarantine effective in reducing the incidence
of COVID-19 cases?
- KQ2a: Are there differences in the effectiveness of quarantine in
different settings?