 The findings, which are
published in the Aug. 8 issue of the Journal of the American
Medical Association, provide vital clues to help public
officials planning for the next influenza pandemic and highlight the
importance of community strategies. 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 available.Scientists from the Centers for Disease
Control and Prevention and the University of Michigan Medical
School's Center for the History of Medicine completed an exhaustive
review of public records such as health department reports, U.S.
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 Journal of the American Medical Association 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 affected 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.
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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.
For more information about community strategies for pandemic
influenza, see
http://www.pandemicflu.gov/plan/
community/community--mitigation.pdf.
[To download Adobe Acrobat Reader for
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here.]
[Text from
Centers for Disease Control and Prevention news release] |
