# 2122
One of the less frequently mentioned aspects of a pandemic is that the better job we do of lessening it's impact and slowing it down, the longer a pandemic wave is expected to last.
While the ultimate presentation of the next pandemic remains unknown, it is assumed that it will come in one or more `waves' over a year or longer. The number and duration of these waves is largely speculative, and based on a very limited data-set.
The chart above, taken from the PNAS journal article entitled Public Health Interventions and Pandemic Intensity During the 1918 Influenza Pandemic, illustrates what happened in two American cities during the 1918 pandemic.
The sharp, but much shorter pandemic wave depicted by the solid line occurred in Philadelphia, where relatively few steps were taken by the public health department to slow the spread of the disease.
The dotted line represents St. Louis, which closed schools early and where the Health Department prohibited public gatherings in places like theaters, churches, and restaurants.
As you can see, the percentage of cases reported on a daily basis were far fewer, but the pandemic wave lasted nearly twice as long as in Philadelphia.
At its worst, the percentage of excess of people afflicted in the city of Philadelphia was 5 times greater than what St. Louis experienced. The burden on hospitals, mortuaries, and practically all segments of the economy was certainly far greater.
The only saving grace was that it was over in 6 weeks instead of 12.
This is the tradeoff we face in a pandemic. Impact vs. duration.
Unchecked, an influenza virus will generally spread through a community until enough of the population becomes immune (through exposure or vaccines) to deny the virus new hosts. Not everyone who is exposed, and develops immunity, will fall ill.
Since the virus cannot live for long outside of a host, once `herd immunity' is reached in a community, the outbreak withers and dies.
With insufficient antivirals, and no prospects of a targeted vaccine during the first pandemic wave, our national strategy is to slow down the virus through the use of NPI's, or Non-Pharmaceutical Interventions.
These may include:
- Social Distancing
- Frequent Hand Washing or Sanitizing
- Covering your coughs and sneezes
- School and day care closures
- Targeted business closures
- The use of masks, gloves, and other barriers
- Isolation of those infected
- Voluntary quarantine of those exposed
In addition, it is hoped that the use of antivirals, particularly for outbreak prophylaxis among high risk employees, may also slow the spread of the disease.
By using these NPI's, and slowing the spread of the virus, it is hoped that the impact on our health-care systems, infrastructure, and overall community can be lessened.
Ironically, the more successful these steps are, the longer a pandemic wave is likely to persist. While this certainly is a downside, I'm convinced it beats the alternative.
This has real-world implications for all of us. Our preparations need to take into account these longer pandemic waves. And while we talk in terms of a `12 week wave', the actual length of a pandemic wave could vary significantly from one community to the next.
The upshot is that individuals, families, and businesses all need to be thinking about how they will function for roughly three months of `pandemic conditions' at a time.
How challenging all of this will be will depend largely on the severity of the next pandemic.
Future Pandemics will be ranked from Category 1 (mild) to Category 5 (severe) based on the CFR (Case Fatality Ratio) of the virus. This chart is from comes from the HHS/CDC document: Interim Pre-Pandemic Planning Guidence: Community Strategy For Pandemic Influenza Mitigation In the United States.
Figure A. Pandemic Severity Index
You will notice that while Category 5 is the top level of the scale, the severity of a CAT 5 pandemic is purposefully left open-ended. There is a growing acceptance in official circles that a `1918-style pandemic' is not the worst that nature could throw at us.
The bottom line is that for a society to function, and for essential services to continue during a pandemic, we all need to be preparing for a long haul.
Businesses, individuals, families, and communities.
Yes, I know it will be frightfully expensive, unpopular, and difficult to sell to the public. To many people, all of this may seem unreasonable.
But a pandemic isn't something you can reason with. You can't explain the difficulties involved and try to bargain with a virus.
A pandemic doesn't care.
It just is.
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