NPI's: The Long And The Short Of It
# 680
The prevailing theory, based on our experiences in the Spanish Flu of 1918-1919, is that a pandemic will come in several waves lasting 6 to 12 weeks, occurring over a year or two. Whether that holds true for the next pandemic is unknown.
The world is a far different place than it was 89 years ago, and our more mobile society may change the equation.
The chart above, taken from the PNAS journal article entitled Public Health Interventions and Pandemic Intensity During the 1918 Influenza Pandemic , shows the excess mortality in two American cities. The tall spike represents Philadelphia, while the lower curve represents St. Louis.
Scientists believe the startling difference in attack rates, and mortality, in these two cities can be explained by the way each city dealt with the outbreak. In St. Louis, the Health Department closed public venues such as schools, theatres and churches very early in the outbreak, while Philadelphia did not.
As a result, Philadelphia experience a sharper, albeit shorter pandemic wave. St. Louis saw fewer deaths on a weekly basis, but the outbreak lasted longer. Roughly twice as long, in fact.
The uptick in cases in St. Louis, late in the outbreak, indicates that some people stopped their social distancing too soon, and the pandemic wave re-ignited.
Given the absence of vaccines, or other pandemic medicines, the CDC is looking towards the use of NPI's (Non-Pharmaceutical Interventions) such as school closures, and social distancing, to blunt the impact of a pandemic.
It is hoped that by reducing the number of people simultaneously infected, the impact on society will be lessened. Hospitals would be better able to cope, and essential services would be less strained by absenteeism and demands on their departments.
The choice, it seems, is between a short pandemic wave, where we see a lot of infections (and deaths) over a relatively short time span, or a longer wave, with fewer weekly infections.
The total number of infections, and deaths, may not differ much in the end. But the impact on society, and the demands on services would be lower with a longer, less steep infection curve.
Obviously, a longer wave entails some difficulties that a shorter wave does not. Schools would remained closed for up to 3 months, many businesses would take a prolonged economic hit, and people would need to be prepared for longer periods of isolation.
Still, when you consider the alternatives, the St. Louis model is far preferable.
The point of this little exercise is to illustrate that people need to be prepared to weather a viral storm that may last for several months.
That means that the two-weeks of supplies generally recommended by government agencies may not be enough. And that people need to be prepared to have their kids home from school, and they may find themselves out of work, for several months.
The good news is, the use of NPI's does appear to have a beneficial effect on a pandemic. And right now, that is the best weapon we have in our arsenal.
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