Health Policy
www.thelancet.com Vol 396 July 4, 2020 65
Wuhan from other cities, expanding nucleic acid testing
capacity to 35 000 tests per day in February, 2020. These
hospitals and laboratories helped ensure that every
suspected case could be tested, treated, and isolated,
and that their close contacts could be traced and isolated
in a timely manner.31–33
Citizen support has been essential. People not
providing essential services had to remain at home as
much as possible; everyone had to avoid gatherings and
wear masks when going out. Wuhan suspended all
transportation in and out of the city from Jan 23 to
April 8, 2020. Varying degrees of intra-area and interarea
transportation restrictions were applied throughout the
entire country, from big cities to small villages, for at
least 1 month. Many volunteers supported the community
control policies. Timeliness was stressed, with hospitals
required to report confirmed or suspected cases within
2 h, laboratories to report test results within 12 h, and
local Centers for Disease Control and Prevention to
complete case investigations within 24 h.
Modelling estimated that, had this containment effort
not been done, the number of COVID-19 cases would
have been an estimated 67-fold higher than they have
been thus far.34 According to this model, detection,
isolation, and contact tracing with quarantine was the
most effective part of the containment strategy, which was
estimated to have prevented more infections than travel
restriction and contact reductions.34 Integration with NPIs
served to strengthen and accelerate the effect of detection,
isolation, tracing, and quarantine.34 Suspending intracity
public transport, closing entertainment venues, and
prohibiting mass gatherings were also associated with
reductions in case incidence.35
Suppression
We use a suppression strategy for when an epidemic is in
multiple areas with varying degrees of outbreak and
community spread, when it is not possible or feasible to
stop spreading by confining transmission to an isolatable
geographical area. Core measures are similar to those for
containment and are summarised in table 2. Suppression
logically follows successful containment to prevent
spread from imported cases and re-establishment of
community transmission.
Suppression measures can keep transmission and
prevalence low, decreasing the effective reproduction
number (Re).36 Once Re is below 1 in a community, spread
in that community should eventually stop. However,
maintenance of strict suppression measures, particularly
physical distancing, brings a large socioeconomic burden.
As shown by scientists at Imperial College London,37
intermittent physical distancing triggered by trends in
disease surveillance can allow interventions to be relaxed
temporarily in short time windows, but measures will
need to be reintroduced if or when case numbers begin to
rebound. Therefore, a challenge for suppression is to
balance the needs of epidemic control with restoration
and maintenance of social life, choosing epidemiologically
appropriate times to relax or strengthen control.
Importantly though, during times of more relaxed
physical distancing efforts, proactive case detection and
management with contact tracing and quarantine must
be maintained, to avoid re-establishment of community
transmission and a rebound of the epidemic.
Achievability and feasibility of containment and
suppression
SARS-CoV-2 is mainly transmitted by symptomatic cases.
Analysis of nucleic acid tests in a cohort with 2147 close
contacts showed that only 17% (22 of 132) of cases were
asymptomatic among all nucleic acid test-positive cases.38
Similarly, in the Diamond Princess cruise ship outbreak,
approximately 18% of nucleic acid test-positive cases
were asymptomatic.39 Based on national surveillance data
from China, clinical manifestations of COVID-19 are
readily identifiable in most patients, with more than
half developing pneumonia, which facilitates early case
finding.21,22,40,41 Although presymptomatic and even asymptomatic
infected individuals can transmit the virus, their
ability to transmit is much lower than that of symptomatic
infected individuals.42–44 By actively identifying symptomatic
patients and expanding testing of their close
contacts, a large burden of asymptomatic infection can be
detected, and with infected individuals appropriately
isolated at an early stage, risk of transmission will be
reduced. Low transmissibility of asymptomatic cases, and
the ease with which symptomatic cases can be diagnosed
using readily available, sensitive, and specific diagnostic
tests, support the notion that transmission can be
interrupted by finding and managing cases and tracing
and quarantining their close contacts.
The core containment and suppression strategies are
worthwhile, not only in an early stage of the epidemic
but also during a later community transmission stage.
With limited community transmission, as was seen in
provinces outside Hubei in China, containment was
achieved within a month. Widespread community transmission
of SARS-CoV-2 in Hubei (population 59 million)
was stopped in less than 2 months (figure).
The most urgent and important measure of the
containment and suppression strategies is scaling up
testing of each suspected case and all close contacts of
those infected.45,46 With the increase in PCR testing
capacity in China as an example, the median time from
illness onset to diagnosis was shortened from an initial
average of 12 days in early January to only 3 days in early
February.47
After containment in China
The current situation of COVID-19
The containment strategy has largely been successful in
China. From April 1 to May 31, 2020, there have been,
on average, 54 infections reported daily by China’s
National Health Commission, which were almost all
www.thelancet.com Vol 396 July 4, 2020 65
Wuhan from other cities, expanding nucleic acid testing
capacity to 35 000 tests per day in February, 2020. These
hospitals and laboratories helped ensure that every
suspected case could be tested, treated, and isolated,
and that their close contacts could be traced and isolated
in a timely manner.31–33
Citizen support has been essential. People not
providing essential services had to remain at home as
much as possible; everyone had to avoid gatherings and
wear masks when going out. Wuhan suspended all
transportation in and out of the city from Jan 23 to
April 8, 2020. Varying degrees of intra-area and interarea
transportation restrictions were applied throughout the
entire country, from big cities to small villages, for at
least 1 month. Many volunteers supported the community
control policies. Timeliness was stressed, with hospitals
required to report confirmed or suspected cases within
2 h, laboratories to report test results within 12 h, and
local Centers for Disease Control and Prevention to
complete case investigations within 24 h.
Modelling estimated that, had this containment effort
not been done, the number of COVID-19 cases would
have been an estimated 67-fold higher than they have
been thus far.34 According to this model, detection,
isolation, and contact tracing with quarantine was the
most effective part of the containment strategy, which was
estimated to have prevented more infections than travel
restriction and contact reductions.34 Integration with NPIs
served to strengthen and accelerate the effect of detection,
isolation, tracing, and quarantine.34 Suspending intracity
public transport, closing entertainment venues, and
prohibiting mass gatherings were also associated with
reductions in case incidence.35
Suppression
We use a suppression strategy for when an epidemic is in
multiple areas with varying degrees of outbreak and
community spread, when it is not possible or feasible to
stop spreading by confining transmission to an isolatable
geographical area. Core measures are similar to those for
containment and are summarised in table 2. Suppression
logically follows successful containment to prevent
spread from imported cases and re-establishment of
community transmission.
Suppression measures can keep transmission and
prevalence low, decreasing the effective reproduction
number (Re).36 Once Re is below 1 in a community, spread
in that community should eventually stop. However,
maintenance of strict suppression measures, particularly
physical distancing, brings a large socioeconomic burden.
As shown by scientists at Imperial College London,37
intermittent physical distancing triggered by trends in
disease surveillance can allow interventions to be relaxed
temporarily in short time windows, but measures will
need to be reintroduced if or when case numbers begin to
rebound. Therefore, a challenge for suppression is to
balance the needs of epidemic control with restoration
and maintenance of social life, choosing epidemiologically
appropriate times to relax or strengthen control.
Importantly though, during times of more relaxed
physical distancing efforts, proactive case detection and
management with contact tracing and quarantine must
be maintained, to avoid re-establishment of community
transmission and a rebound of the epidemic.
Achievability and feasibility of containment and
suppression
SARS-CoV-2 is mainly transmitted by symptomatic cases.
Analysis of nucleic acid tests in a cohort with 2147 close
contacts showed that only 17% (22 of 132) of cases were
asymptomatic among all nucleic acid test-positive cases.38
Similarly, in the Diamond Princess cruise ship outbreak,
approximately 18% of nucleic acid test-positive cases
were asymptomatic.39 Based on national surveillance data
from China, clinical manifestations of COVID-19 are
readily identifiable in most patients, with more than
half developing pneumonia, which facilitates early case
finding.21,22,40,41 Although presymptomatic and even asymptomatic
infected individuals can transmit the virus, their
ability to transmit is much lower than that of symptomatic
infected individuals.42–44 By actively identifying symptomatic
patients and expanding testing of their close
contacts, a large burden of asymptomatic infection can be
detected, and with infected individuals appropriately
isolated at an early stage, risk of transmission will be
reduced. Low transmissibility of asymptomatic cases, and
the ease with which symptomatic cases can be diagnosed
using readily available, sensitive, and specific diagnostic
tests, support the notion that transmission can be
interrupted by finding and managing cases and tracing
and quarantining their close contacts.
The core containment and suppression strategies are
worthwhile, not only in an early stage of the epidemic
but also during a later community transmission stage.
With limited community transmission, as was seen in
provinces outside Hubei in China, containment was
achieved within a month. Widespread community transmission
of SARS-CoV-2 in Hubei (population 59 million)
was stopped in less than 2 months (figure).
The most urgent and important measure of the
containment and suppression strategies is scaling up
testing of each suspected case and all close contacts of
those infected.45,46 With the increase in PCR testing
capacity in China as an example, the median time from
illness onset to diagnosis was shortened from an initial
average of 12 days in early January to only 3 days in early
February.47
After containment in China
The current situation of COVID-19
The containment strategy has largely been successful in
China. From April 1 to May 31, 2020, there have been,
on average, 54 infections reported daily by China’s
National Health Commission, which were almost all
