|
|
| |
|
|
| |
|
|
|
|
| |
Social Distancing
Social distancing is a set of nonpharmaceutical
infection control actions intended to stop or slow down
the spread of a contagious disease. The objective of
social distancing is to reduce the probability of
contact between persons carrying an infection, and
others who are not infected, so as to minimize disease
transmission, morbidity and ultimately, mortality.
Social distancing is most effective when the infection
can be transmitted via droplet contact (coughing or
sneezing); direct physical contact, indirect physical
contact (e.g. by touching a contaminated surface such as
a fomite); or airborne transmission (if the
microorganism can survive in the air for long periods).
During the 2019–2020 coronavirus pandemic, the World
Health Organization (WHO) suggested the reference to
"physical" as an alternative to "social", in keeping
with the notion that it is a physical distance which
prevents transmission; people can remain socially
connected via technology.
Social distancing may be less effective in cases where
the infection is transmitted primarily via contaminated
water or food or by vectors such as mosquitoes or other
insects, and less frequently from person to person.
Drawbacks of social distancing can include loneliness,
reduced productivity, and the loss of other benefits
associated with human interaction.
Historically, leper colonies and lazarettos were
established as a means of preventing the spread of
leprosy and other contagious diseases through social
distancing, until transmission was understood and
effective treatments were invented. |
|
Examples
Some examples of social distancing used to control the
spread of contagious illnesses include: |
- school closure (proactive or
reactive), online education
- workplace closure, including closure
of “non-essential” businesses and social services
(“Non-essential” means those facilities that do not
maintain primary functions in the community, as opposed
to essential services)
- isolation
- quarantine
- protective sequestration
- cancellation of mass gatherings such
as sports events, films or musical shows
shutting down or limiting mass transit
- closure of recreational facilities
(community swimming pools, youth clubs, gymnasiums)
- "self-shielding" measures for
individuals include limiting face-to-face contacts,
conducting business by phone or online, avoiding public
places and reducing unnecessary travel
- The "elbow bump" (instead of a
handshake for a greeting) and the "Dracula sneeze"
|
|
Effectiveness
Research indicates that measures must be applied
rigorously and immediately in order to be effective.
During the 1918 flu pandemic, authorities in the US
implemented school closures, bans on public gatherings,
and other social distancing interventions in
Philadelphia and in St. Louis, but in Philadelphia the
delay of five days in initiating these measures allowed
transmission rates to double three to five times,
whereas a more immediate response in St. Louis was
significant in reducing transmission there. Bootsma and
Ferguson analyzed social distancing interventions in 16
US cities during the 1918 epidemic and found that
time-limited interventions reduced total mortality only
moderately (perhaps 10–30%), and that the impact was
often very limited because the interventions were
introduced too late and lifted too early. It was
observed that several cities experienced a second
epidemic peak after social distancing controls were
lifted, because susceptible individuals who had been
protected were now exposed.
School closures
School closures were shown to reduce morbidity from the
Asian Flu by 90% during the 1957-58 outbreak, and up to
50% in controlling influenza in the US, 2004–2008.
Similarly, mandatory school closures and other social
distancing measures were associated with a 29% to 37%
reduction in influenza transmission rates during the
2009 flu epidemic in Mexico.
Workplace closures
Modeling and simulation studies based on US data suggest
that if 10% of affected workplaces are closed, the
overall infection transmission rate is around 11.9% and
the epidemic peak time is slightly delayed. In contrast,
if 33% of affected workplaces are closed, the attack
rate decreases to 4.9%, and the peak time is delayed by
1 week.
Quarantine of contacts and
suspected cases
During the 2003 SARS outbreak in Singapore, some 8,000
persons were subjected to mandatory home quarantine and
an additional 4,300 were required to self-monitor for
symptoms and make daily telephone contact with health
authorities as a means of controlling the epidemic.
Although only 58 of these individuals were eventually
diagnosed with SARS, public health officials were
satisfied that this measure assisted in preventing
further spread of the infection. Voluntary
self-isolation may have helped reduce transmission of
influenza in Texas in 2009.
Cordon sanitaire
In 1995 a cordon sanitaire was used to control an
outbreak of Ebola virus disease in Kikwit, Zaire.
President Mobutu Sese Seko surrounded the town with
troops and suspended all flights into the community.
Inside Kikwit, the World Health Organization and Zaire
medical teams erected further cordons sanitaires,
isolating burial and treatment zones from the general
population and successfully containing the infection.
During the 2003 SARS outbreak in Canada, "community
quarantine" was used to reduce transmission of the
disease with moderate success.
Protective sequestration
During the 1918 influenza epidemic the town of Gunnison,
Colorado isolated itself for two months to prevent an
introduction of the infection. All highways were
barricaded near the county lines. Train conductors
warned all passengers that if they stepped outside of
the train in Gunnison, they would be arrested and
quarantined for five days. As a result of the isolation,
no one died of influenza in Gunnison during the
epidemic. Several other communities adopted similar
measures.
Canceling mass gatherings
Evidence suggesting that mass gatherings increase the
potential for infectious disease transmission is
inconclusive. Anecdotal evidence suggests that certain
types of mass gatherings may be associated with
increased risk of influenza transmission, and may also
"seed" new strains into an area, instigating community
transmission in a pandemic. During the 1918 influenza
pandemic, military parades in Philadelphia and Boston
may have been responsible for spreading the disease by
mixing infected sailors with crowds of civilians.
Restricting mass gatherings, in combination with other
social distancing interventions, may help reduce
transmission.
Travel restrictions
Border restrictions and/or internal travel restrictions
are unlikely to delay an epidemic by more than 2–3 weeks
unless implemented with over 99% coverage. Airport
screening was found to be ineffective in preventing
viral transmission during the 2003 SARS outbreak in
Canada and the US. Strict border controls between
Austria and the Ottoman Empire, imposed from 1770 until
1871 to prevent persons infected with the bubonic plague
from entering Austria, were reportedly effective, as
there were no major outbreaks of plague in Austrian
territory after they were established, whereas the
Ottoman Empire continued to suffer frequent epidemics of
plague until the mid-nineteenth century.
A Northeastern University study published in March, 2020
found that "travel restrictions to and from China only
slow down the international spread of COVID-19 [when]
combined with efforts to reduce transmission on a
community and an individual level...Travel restrictions
aren’t enough unless we couple it with social
distancing." The study found that the travel ban in
Wuhan only delayed the spread of the disease to other
parts of mainland China by three to five days, although
it did reduce the spread of international cases by as
much as 80 percent. A primary reason that travel
restrictions were less effective is that many people
with COVID-19 do not show symptoms during the early
stages of infection. |
|
Drawbacks
Drawbacks of social distancing can include an economic
slowdown, loneliness, reduced productivity, and the loss
of other benefits associated with human interaction. In
developing nations where remote technology and personal
protective equipment are not in widespread use, it is
often more difficult for a community to monitor the
health of its members. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Search Fun Easy English |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
About
Contact
Copyright
Resources
Site Map |
