The current coronavirus pandemic has re-emphasized the
complex nature of health decisions. Medical
science informs our decisions, but the science is not exact, or at least our
current capabilities to model and understand these phenomena are not at a level
where we can be completely confident in our analysis.
Some people are outraged or indignant about the precautions
currently being implemented. Part of
this is political in nature, as all things seem to be lately in our
society. But part of it is basic
ignorance of how small uncertainties and differences can play a huge role in
the progression of a pandemic.
Many argue that we should treat this like a flu epidemic,
since flu epidemics spread rapidly and kill tens of thousands of people each
year. They don’t understand why we
should view this disease any differently.
However, there are several factors that can play a dramatic
role in a pandemic, and the coronavirus appears to be just different enough from the flu to
make these factors very significant.
The first is the basic reproduction number - Rₒ, which is an
estimate of how many people a contagious person will infect. The flu typically has an Rₒ of between 1.1
and 1.6. COVID-19 appears to have a much
higher number, around 2.2.
This is a huge difference!
After 20 cycles of transmission the flu, with an Rₒ of 1.4, will infect
about 136 people. When a virus has an Rₒ
of 2.2, twenty cycles will infect 137,000 people!!
The second major factor is the mortality rate. The flu generally has a mortality rate of 0.1%,
meaning that 1 person in a thousand who get sick will die from the flu. COVID-19 appears to have a much higher
mortality rate, anywhere from 1-2.5%.
This means that 1 to 2.5 people out of a hundred will die. This is a very big difference.
There are other important factors – the incubation time and
how long the person is contagious are examples.
All of these factors are estimated from data collected. We have years and years of data from the flu
and understand the threat quite well. The
exact opposite is true of COVID-19. We
are learning in real-time and having to make decisions based on limited data.
Another key aspect of managing the pandemic is the ability of
healthcare services to treat people with the disease. Hospitals and healthcare providers are not
prepared to respond to huge surges in sickness.
They make heroic efforts, but they simply do not have the beds, the equipment
(respirators, etc.), the qualified people, or the quantity of drugs necessary
to deal with massive increases in infected patients.
We have seen what the combination of high Rₒ, high mortality
rate, and limits on healthcare facilities can do in Wuhan, Italy and Iran. The mortality rate in these places rose well
above the expected mortality rate because a triage situation occurred and many
patients who could have been saved were abandoned because of the overwhelming
number of desperately ill people. Those examples make it clear what can happen
when little is done to defend against the spread of the disease.
The tricky thing is that there are really no half measures
that one can employ to control contagion.
The usual recommendations of washing hands and covering your mouth when
you cough are simply not enough to limit the spread of something with such a
large Rₒ. And the risk of creating a
situation like those mentioned above is too high. The only real solution until all of the cases
are known and tracked is isolation and social distancing.
The sad fact is that these extreme measures, though
certainly justified and necessary, will necessarily cause widespread hardship. A world recession of unknown depth and
duration will certainly occur. I hope
that it will bring out the better angels in our human nature and teach us to
care for one another and this fragile earth.
Perhaps it will be the wake up call we need?
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