Michigan-CDC study supports value of social restrictions during influenza pandemics

August 07, 2007

ANN ARBOR, Mich. -- Although physicians have imposed quarantine orders since at least 1374, when the Port of Venice officially isolated foreigners and shippers for 40 days to keep out infectious scourges, there has been no definitive evidence that public health measures like quarantining the sick and isolating people after exposure to ill people would save lives during an influenza pandemic.

Until now.

In a study published in the Aug. 8 Journal of the American Medical Association, a team of University of Michigan medical historians and epidemiologists from the federal Centers for Disease Control and Prevention say that social restrictions allowed 43 U.S. cities to save thousands of lives during the Spanish influenza pandemic of 1918-1919.

Although these urban communities had neither effective vaccines nor antiviral medicines, they were able to organize and execute a suite of classic public health measures - called non-pharmaceutical interventions or NPIs - before the pandemic gained full force.

The new study finds that cities whose NPIs were sustained and layered with multiple tactics had the best outcomes. In addition to quarantine and isolation, the NPIs examined in this study were school closures and cancellation of public gatherings.

"Public health is everyone's responsibility. In a world faced by the threat of newly emerging and re-emerging infectious diseases, it is critical to determine if costly and potentially socially harsh NPI measures can save lives and reduce the numbers of those infected," says lead author Howard Markel, M.D., Ph.D., the George E. Wantz Distinguished Professor of the History of Medicine, professor of pediatrics and communicable diseases, and director of the U-M Center for the History of Medicine. "Now we know the answer is 'yes.' "

Markel adds that in today's world, implementing these measures in a layered, sustained fashion would also provide a cushion of time for the development and distribution of effective vaccines and antivirals, while reducing the crush on essential infrastructure.

"By better understanding what worked in the past, we can better prepare for the future," says senior author Martin Cetron, M.D., director of the CDC's Division of Global Migration and Quarantine. "Communities that were most successful during the 1918 pandemic quickly enacted a variety of measures. 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."

The 43 cities in the study were scattered from coast to coast and represented a combined population of approximately 23 million. In an exhaustive review of 1,144 primary and secondary sources that included U.S. census data, municipal records, newspapers and handbills covering a 24-week period - Sept. 8, 1918 through Feb. 22, 1919 - the researchers identified which NPIs were used in each city and when officials turned them on and off.

Using both actual death rates from pneumonia and influenza, and baseline rates for what would have been normal without a pandemic, the researchers found there were 115,340 excess pneumonia and influenza deaths attributable to the pandemic in these cities during the period studied. In comparing the death rates to when NPIs were turned on and off, they found that NPIs did mitigate the death rate, with a statistically significant association between increased duration of NPIs and reduced mortality.

Further, they discovered that city-to-city variation in mortality was associated with the timing, duration and combination of NPIs. St. Louis, Missouri, for example, closed schools and cancelled public gatherings relatively early in the pandemic and sustained these measures for about 10 weeks. The analysis shows that St. Louis had one of the largest drops in mortality while the NPIs were in force.

As a whole, the study's findings contrast markedly with the conventional wisdom that the Spanish Flu ravaged the United States and elsewhere, with little that could be done to stop its deadly toll.

Markel predicts that NPI measures will be socially painful in the next pandemic, but that the public's acceptance of NPIs is essential.
-end-
"We need to have informed concern about what to do in a pandemic - and why," concludes Markel.

Citation: JAMA, Nonpharmaceutical Interventions Implemented by US Cities During the 1918 -1919 Influenza Pandemic, Aug. 8, 2007, p. 644-654, Vol. 298, No. 6.

Other collaborators on the research were Alexandra Minna Stern, Ph.D., associate director, Center for the History of Medicine; J. Alexander Navarro, Ph.D., senior researcher, Center for the History of Medicine; Joseph R. Michalsen, research associate, Center for the History of Medicine; Alexandra Sloan, research associate, Center for the History of Medicine; and Harvey B. Lipman, Ph.D., (insert title), Centers for Disease Control and Prevention.

This work was funded by the Centers for Disease Control and Prevention and conducted by the University of Michigan Center for the History of Medicine and the CDC Division of Global Migration and Quarantine.

The complete bibliography of the 1,144 primary and secondary sources is available as an online supplement at www.cdc.gov/ncidod/dq/index.htm. The supplement provides access to data specific to each of the 43 cities.

The Center for the History of Medicine also has a Web-based source of materials that cover the 1918-919 influenza pandemic, which can be viewed at www.med.umich.edu/medschool/chm/influenza/.

More information about community strategies for pandemic influenza is available at www.pandemicflu.gov/plan/community/commitigation.html.

The 43 cities examined in this study were:

AL: Birmingham
CA: Los Angeles, Oakland, San Francisco
CO: Denver
CT: New Haven
DC: Washington
IL: Chicago
IN: Indianapolis
KY: Louisville
LA: New Orleans
MA: Boston, Cambridge, Fall River, Lowell, Worcester
MI: Grand Rapids
MD: Baltimore
MN: Minneapolis, St. Paul
MO: Kansas City, St. Louis
NE: Omaha
NJ: Newark
NY: Albany, Buffalo, New York, Rochester, Syracuse
OH: Cincinnati, Cleveland, Columbus, Dayton, Toledo
OR: Portland
PA: Philadelphia, Pittsburgh
RI: Providence
TN: Nashville
VA: Richmond
WA: Seattle, Spokane
WI: Milwaukee

University of Michigan Health System

Related Influenza Articles from Brightsurf:

Predicting influenza epidemics
Researchers at Linköping University, Sweden, have developed a unique method to predict influenza epidemics by combining several sources of data.

Common cold combats influenza
As the flu season approaches, a strained public health system may have a surprising ally -- the common cold virus.

Scent-sensing cells have a better way to fight influenza
Smell receptors that line the nose get hit by Influenza B just like other cells, but they are able to clear the infection without dying.

New antivirals for influenza and Zika
Leuven researchers have deployed synthetic amyloids to trigger protein misfolding as a strategy to combat the influenza A and Zika virus.

Assessment of deaths from COVID-19, seasonal influenza
Publicly available data were used to analyze the number of deaths from seasonal influenza deaths compared with deaths from COVID-19.

Obesity promotes virulence of influenza
Obesity promotes the virulence of the influenza virus, according to a study conducted in mice published in mBio, an open-access journal of the American Society for Microbiology.

Influenza: combating bacterial superinfection with the help of the microbiota
Frenc researchers and from Brazilian (Belo Horizonte), Scottish (Glasgow) and Danish (Copenhagen) laboratories have shown for the first time in mice that perturbation of the gut microbiota caused by the influenza virus favours secondary bacterial superinfection.

Chemists unveil the structure of an influenza B protein
MIT chemists have discovered the structure of an influenza B protein called BM2, a finding that could help researchers design drugs that block the protein and help prevent the virus from spreading.

How proteins help influenza A bind and slice its way to cells
Researchers have provided new insight on how two proteins help influenza A virus particles fight their way to human cells.

Eating elderberries can help minimize influenza symptoms
Conducted by Professor Fariba Deghani, Dr. Golnoosh Torabian and Dr.

Read More: Influenza News and Influenza Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.