Public Health Guidance for Community-Level Preparedness and Response to
Severe Acute Respiratory Syndrome (SARS) Version 2

Supplement: Community Containment Measures, Including Non-Hospital
Isolation and Quarantine

Appendix D2

Frequently Asked Questions about Use of Community Containment Measures

**If SARS-CoV reappears in the United States, will quarantine definitely
be required and used?**

No. Quarantine is only one of a spectrum of actions that may be
considered during a future SARS outbreak in the United States. Although
rapid control is likely to require bold and swift action, measures that
are less drastic than legally enforced quarantine may suffice, depending
on the epidemiologic characteristics of the outbreak. For example,
active monitoring without activity restrictions may be adequate when
most cases are either imported or have clear epidemiologic linkages at
the time of initial evaluation. When the epidemiology of the outbreak
indicates a need for stronger measures, jurisdictions can adopt a
voluntary quarantine approach and reserve legal measures only for those
who fail to comply. When an outbreak progresses to include large numbers
of cases for which no epidemiologic linkages can be identified,
community-level interventions may become necessary. Even at this stage,
however, measures designed to increase social distance, such as
snow-days, may be preferred alternatives. Wider use of quarantine is
generally reserved for situations in which all other control measures
are believed to be ineffective.

The choice of containment measures requires frequent and ongoing
assessment of an outbreak and evaluation of the effectiveness of
existing control measures. Officials must be prepared to make decisions
based on limited information and then modify those decisions as
additional information becomes available.

### 

### Does the effectiveness of containment measures require 100% compliance?

No. Containment measures, including quarantine, are effective even if
compliance is less than 100%. Even partial or "leaky" quarantine can
reduce transmission. Therefore, strict legal enforcement is not
necessarily always needed; in most cases, jurisdictions can rely on
voluntary cooperation. Modeling studies of the relative contributions of
quarantine and vaccination in control of smallpox outbreaks suggest a
benefit from quarantine even when compliance is as low as 50%. The
incremental benefit of quarantine approaches a maximum at a compliance
rate of approximately 90%, with little additional benefit from higher
rates of compliance. Therefore, containment measures can be important
components of the response to a communicable disease outbreak even when
compliance is not high.

**Does "quarantine" always mean using a legal order to restrict
someone's activity?**

No. The term "quarantine" is often defined narrowly to refer to the
legally mandated separation of well persons who have been exposed to a
communicable disease from those who have not been exposed. Although the
precise legal definition of quarantine may differ from jurisdiction to
jurisdiction, when used clinically or programmatically, quarantine may
be defined more broadly to include all interventions, both mandatory and
voluntary, that restrict the activities of persons exposed to a
communicable disease. Therefore, whenever an exposed person is placed
under a regimen of monitoring that includes an activity restriction,
even when those restrictions are adhered to voluntarily, the person is
said to be under quarantine.

### 

### Must quarantine be mandatory to be effective?

No. Although the federal government and nearly all states have the legal
authority to place persons exposed to certain communicable diseases
under quarantine and enforce the required restrictions on activity, use
of this authority may not always be necessary or practical. Previous
experiences with the use of quarantine, including those during the 2003
SARS outbreaks, suggest that the majority of persons comply voluntarily
with requests from health authorities to remain in quarantine and
observe the recommended activity restrictions.

During the 2003 outbreaks, at least one jurisdiction outside the U.S.
used an incremental approach to institution of quarantine. A request for
voluntary quarantine resulted in compliance by more than 90% of affected
persons. Those who did not adhere to the request were served with a
legally enforceable order. This approach has the advantage of being
perceived by the public as being less severe, since compliance with the
initial request is voluntary. In addition, in jurisdictions where
prevailing statutory quarantine authorities require separate orders for
each person placed under activity restrictions, this approach reduces
the legal workload to a more practical level.

**Does being placed in quarantine increase a person's risk for acquiring
disease?**

Historically, placement in quarantine has been associated with increased
disease transmission. One reason may be that separation between ill and
well persons was not maintained. One of the fundamental principles of
modern quarantine is that persons in quarantine are to be closely
monitored so that those who become ill are efficiently separated from
those who are well. A second principle is that persons in quarantine
should be among the very first to receive any available
disease-prevention interventions. Adherence to these two principles of
modern quarantine should prevent an increase in risk for acquiring
disease while in quarantine.

**Is quarantine really necessary if everyone who develops symptoms is
rapidly placed in isolation?**

Although theoretically true, it would be unrealistic to believe that
even the most efficient system for initiation of isolation will minimize
delays to the extent required to prevent transmission. Among the factors
contributing to delays in recognition of symptoms are the insidious
nature of disease onset and denial that symptoms have developed. Early
in the 2003 outbreak in Singapore, the average delay from onset of
symptoms to initiation of isolation was 7 days. Officials were able to
reduce this delay only to 3 days, even with an aggressive public
awareness campaign on the importance of symptom recognition and
isolation.

Quarantine helps to reduce transmission associated with delays in
isolation in two ways. First, quarantine enables health officials to
quickly locate symptomatic persons who should be placed in isolation.
Second, although quarantine locations may not be as efficient as
isolation facilities in preventing transmission, quarantine reduces the
number of persons who might be exposed while awaiting transfer to an
isolation facility. If quarantine was not used, symptomatic and
infectious persons could move about freely in public places, potentially
exposing large numbers of additional persons and thereby fueling the
outbreak.

**Is quarantine useful only for diseases in which transmission is
possible before the onset of symptoms?**

No. Although quarantine clearly has benefits for prevention of diseases
in which the period of communicability precedes onset of symptoms, a
second, often overlooked, benefit is relevant to diseases such as SARS,
in which infectiousness is likely to coincide with the onset of
symptoms. Quarantine facilitates both close monitoring and prompt
follow-up of persons who are at high risk for developing disease. Both
these factors are likely to reduce the delay in initiation of isolation
following onset of symptoms. Quarantine also limits the number of
additional persons exposed if the quarantined person develops disease.
Thus, quarantine can be a useful strategy even with diseases that are
infectious only after symptoms develop.

**Is quarantine useful only for diseases that are spread by the airborne
route?**

No. Quarantine simply refers to the separation and restriction of
activity of persons exposed to a communicable disease who are not ill.
It is designed to minimize interactions between those exposed to a
disease and those not yet exposed. As such, quarantine can be used for
any disease that is spread from person to person. In practice, however,
because the activity restrictions associated with quarantine infringe on
personal liberties, the intervention is generally reserved for diseases
that are easily and rapidly spread from person to person. The indication
for quarantine for diseases purely transmitted by the airborne route is
clear. However, this tool can also be useful where transmission can
occur through close personal contact with secretions or objects
contaminated by an ill person. Smallpox is an excellent example of a
disease where quarantine can be effective in controlling spread although
transmission may occur by means other than the airborne route.

### 

### Will the public accept the use of quarantine?

Yes. The negative connotations associated with quarantine likely stem
from its misuse or abuse in the past. Although inappropriate use of
quarantine, either voluntary or mandatory, would not and should not be
accepted by the public, efforts should be made to gain public acceptance
when use of this measure is indicated. Experiences with the use of
quarantine during the SARS outbreaks of 2003 suggest that public
acceptance of quarantine may be greater than previously thought. In
Canada, almost all persons asked to observe quarantine restrictions did
so willingly, with only a small number requiring a legal order to gain
cooperation. In all cases, cooperation and acceptance was achieved
through clear and comprehensive communication with the public about the
rationale for use of quarantine.

Number range CHAPTER

For more information, visit
[www.cdc.gov/ncidod/sars](http://www.cdc.gov/ncidod/sars/) or call the
CDC public response hotline\
at (888) 246-2675 (English), (888) 246-2857 (Español), or (866) 874-2646
(TTY)