By the time officials there grasped the threat of the virus, it was too late. The disease was rampaging through the population, partly because the city had allowed large public gatherings, including a citywide parade in support of a World War I loan drive, to go on as planned. In four months, more than 12,000 Philadelphians died, an excess death rate of 719 people for every 100,000 inhabitants.
The story was quite different in St. Louis. Two weeks before Philadelphia officials began to react, doctors in St. Louis persuaded the city to require that influenza cases be registered with the health department. And two days after the first civilian cases, police officers helped the department enforce a shutdown of schools, churches and other gathering places. Infected people were quarantined in their homes.
Excess deaths in St. Louis were 347 per 100,000 people, less than half the rate in Philadelphia. Early action appeared to have saved thousands of lives.
Until vaccines become widely available the extent of deaths from a highly lethal flu pandemic depend on how far governments, businesses, and individuals will go to reduce exposure of humans to other humans. Coming advances in biotechnology will decrease the length of the window from when a flu strain starts spreading to when vaccines become available to stop it. But if a dangerous pandemic started right now we'd be facing 6 to 12 months before vaccines become available in developed countries and longer in less developed countries.
Recent research papers show that extensive isolation of populations instituted starting early in a flu pandemic can greatly reduce the death toll.
This month, researchers published two new studies in The Proceedings of the National Academy of Sciences comparing public-health responses in cities like St. Louis and Philadelphia.
Using mathematical models, they reported that such large differences in death rates could be explained by the ways the cities carried out prevention measures, especially in their timing. Cities that instituted quarantine, school closings, bans on public gatherings and other such procedures early in the epidemic had peak death rates 30 percent to 50 percent lower than those that did not.
If something with the lethality of the avian H5N1 flu breaks out into the human population with mutations that make it easily transmissible then you are going to face a decision: how much will you change your home and work life and family life to reduce or eliminate your exposure to others? Suppose the flu strain is like the 1918 strain and hits the middle aged much harder and, if infected, you face a 10% or 20% chance of dying. What would you do and sacrifice for a year to avoid dying? Mind losing your job or becoming very poor or isolated?
In the extreme you could go home with lots of food stocks and other supplies and stay there for 6 to 12 months. Or, if you live in an apartment building where sitting at home does not totally eliminate exposure risks (think of those Hong Kong apartment buildings which spread SARS infections through ventilation systems) then you could move out into a wilderness cabin or a houseboat or motorhome at an isolated location.
If you work in an occupation which is amenable what I call "workplace cocooning" (quarantined workplaces where people never leave or enter) then you can come through in better economic shape. Unless you already have all the money you need working through a pandemic is the best way to get through it.