Isolation & Quarantine
Measures in Response to a Smallpox Emergency
Isolation
in Practice
When
possible, it is preferable to have patients and contacts willingly
submit to isolation and quarantine. Fewer public health and police
resources would be needed. However, when necessary, both isolation
and quarantine can be invoked under existing laws with law enforcement
authorities assisting in its implementation. Isolation and quarantine
as a necessary control measure for smallpox is inherent as preventing
contagious individuals from transmitting disease to susceptible
individuals is an important step for all transmissible diseases.
However, it may not be feasible as the only control measure.
Modeling by
Meltzer et al. that looked at control measures to contain an outbreak
with 100 people initially infected showed:
- By using
isolation/quarantine (or removal of contagious individuals) alone,
it would take an estimated 240 days to contain the outbreak,
with a resultant 2,300 cases. But, would require that a 50% removal
rate of infectious cases be maintained. This high a removal rate
may be very difficult to achieve.
- Also the
use of quarantine alone at that level may not be acceptable in
today’s society. Preparations must be made for all levels
of interventions.
- Vaccination
alone could also be effective, however, vaccination coverage
would have to be sufficient to reduce the transmission rate from
3/case to less than 1/case; this could also be a difficult target
to achieve.
- With a combination
strategy that only achieved 25% removal or a reduction of transmission
of 3/case to 2/case (much more achievable targets), the outbreak
could still be terminated within 1 year. Any increase in either
the percent removal or the reduction in transmission via vaccination
coverage would decrease the number of cases and shorten the time
interval to contain the outbreak.
Theoretically,
quarantine alone can stop an outbreak. However, the level of quarantine
that would be necessary according to some outbreak models, may
be impossible to achieve and enforce with large numbers of people.
Relying solely on either a vaccination or quarantine strategy alone
is probably unwise. Combining the two would be the most reasonable
and achievable strategy, given limited vaccine and personnel resources.
Planning of
control strategies should take into account various numbers of
cases and various levels of rates of transmission. Smaller numbers
of cases with lower transmission rates could be controlled with
isolation of cases and a smaller amount of vaccine and lower amounts
of vaccine. Larger numbers or higher transmission rates would require
more vaccine, if appropriate amounts of vaccine were unavailable,
quarantine and isolation may become a greater part of the control
strategy and resources would have to be available to implement
these measures to a greater degree. Planning for any scenario should
include how to intervene as quickly as possible.
Isolation
would be instituted for individuals with smallpox and those potentially
infectious. The level of isolation requirements would depend upon
resources and facilities and the degree to which the community
is affected (number of cases, etc.). Those who are known or presumed
to be infectious should be placed in a facility like those previously
discussed, where contact with non-protected (non-vaccinated) individuals
can be prevented. Those contacts who are febrile, but who have
not developed a rash, can be placed in an isolation facility or
may be monitored at home for the development of rash if this can
be done easily and in a manner that will prevent unvaccinated individuals
from entering the home and the person from leaving the home until
it is determined they do not have smallpox. Those contacts who
are asymptomatic can be monitored for symptoms in their own home
with travel restrictions. Example travel restrictions would be
distance restrictions that keep them close enough to their home
such that they could return to home via ground transportation (preferably
in their own vehicle and not via public transportation so that
others would not be exposed) within 1-2 hours if they were to develop
a fever (note: air transportation that would allow a person to
return home within a few hours would not be considered acceptable).
The numbers
of these types of individuals (numbers of cases, numbers exposed,
etc.) and the community resources would then help to shape the
other population-wide response and control measures that may be
implemented.
|