Researchers in the United States have discovered that public health measures such as quarantines, school closings and bans on public gatherings greatly reduce the death toll in flu pandemics.
A pandemic occurs when a flu strain such as the avian flu, mutates so that it acquires the ability to pass between people easily.
Experts believe that current vaccines and people's immune systems will not offer protection against such a new infectious virus, like the Spanish flu in 1918-19 which killed 40 million people, 550,000 of them in the United States.
The risk of a flu pandemic has been in the news since 2003 with the re-emergence of the deadly H5N1 strain of bird flu.
Dr. Howard Markel, director of the University of Michigan Center for the History of Medicine says even today it will still take six months once a pandemic starts to have enough vaccine manufactured and distributed.
Dr. Markel and specialists at the University of Michigan worked with experts at the U.S. Centers for Disease Control and Prevention on non-medical protective measures taken in 43 cities from Sept. 8, 1918, through Feb. 22, 1919.
Although these urban communities had no effective vaccines or antiviral drugs, 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.
They examined public health records, newspaper reports and other chronicles of activity and found that those cities that responded earliest and sustained their response did best.