Rapid action in the community can prevent deaths during pandemic
A study of the 1918-1919 influenza pandemic has shown that early
intervention to isolate infected people slowed down the spread of the
disease and saved lives, according to a new study based on public records
from the time.
Rapid action in local communities, such as school closures and other
strategies designed to reduce the possibility of spreading disease between
people during an epidemic can save lives, particularly when the measures are
used in combination and implemented soon after an outbreak begins in a
community, according to the study.
Scientists from the Centers for Disease Control and Prevention (CDC) and
the University of Michigan Medical School's Center for the History of
Medicine studied public records such as health department reports, US Census
mortality data and newspaper archives.
"Communities that were most successful during the 1918 pandemic quickly
enacted a variety of measures," said Dr. Martin Cetron, director of CDC's
Division of Global Migration and Quarantine and senior author of the study.
"Those planning for the next pandemic need to carefully consider how to best
use these strategies to protect people and decrease the potential impact of
the next pandemic in their communities."
These strategies — voluntary isolation and quarantine, dismissal of
students from school classrooms, and social distancing in the workplace and
community — form the basis for CDC's guidelines for how American communities
can empower themselves to confront the next influenza pandemic.
The findings are published in the Aug. 8 issue of the Journal of the
American Medical Association. These strategies are particularly important
because the intervention most likely to provide the best protection against
pandemic influenza —a vaccine — is unlikely to be available at the outset of
a pandemic. Community strategies that delay or reduce the impact of a
pandemic (also called non-pharmaceutical interventions) may help reduce the
spread of disease until a vaccine that is well-matched to the virus is
The JAMA study evaluated public health measures such as school closures
and cancellation of public events, which 43 American cities took during the
1918 pandemic. The researchers sought to determine whether the timing,
duration and combination of such measures impacted the city's death rate
during the pandemic.
To determine the public health measures' effectiveness, the researchers
analyzed each city's excess death rate — the number of pneumonia and
influenza deaths in excess of the amount expected for the time period.
During a 24-week period in 1918-1919, more than 115,000 excess pneumonia
and influenza deaths in the 43 cities were attributed to the pandemic.
Cities that began interventions earlier had more success in decreasing
excess deaths than those that implemented the measures later, regardless of
how long the later interventions were in place or how they were executed.
In a telling example, New York City's early and sustained response,
including isolation and quarantine and staggered business hours, resulted in
the lowest excess death rate for any city on the East Coast during the time
period reviewed. By contrast, Pittsburgh was well into its outbreak before
implementing the interventions and experienced the highest excess death rate
of any of the 43 cities.
"In a world faced by the threat of avian influenza or other novel strains
of influenza, it is critical to determine if such costly and socially harsh
measures as school closures and cancellation of public gatherings might not
only lower death and case rates, but also delay the spread and allow time
for the development and distribution of effective vaccines and antivirals,"
said Dr. Howard Markel, director of the University of Michigan Medical
School's Center for the History of Medicine and lead author of the study.
"We have demonstrated that these measures can have a real impact."
The interventions assessed fell into three major categories: school
closures, bans on public gatherings and isolation of sick people and
quarantine of their healthy household contacts. The most common approach was
closing schools combined with banning public gatherings. All but three of
the 43 communities closed schools during the 24-week period studied.
Influenza pandemics occur when a new influenza virus emerges to which
most people have little or no immunity and the virus gains the ability to
spread easily between people. The 1918 pandemic sickened about 20 percent of
the world's population and caused an estimated 40 million deaths worldwide,
about 550,000 of them in the United States.
More information about community strategies for pandemic influenza:
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