Retrospective on the Covid-19 Coronavirus outbreak, March 2020

We are now heading toward the back of the curve for the COVID-19 outbreak.  These are my notes thinking about how to deal with the virus based on what I've read.

We know that without preventions, the R0 of COVID-19 is about 3.  Unchecked, this will lead to exponential infection.  More on R0 here.

Models say that 65%+ of a population need be infected before herd immunity starts to work. With a mortality rate of about 1%, this means a significant number of deaths before herd immunity starts to work.

There is no vaccination and because this is a novel virus, no one has had the disease before and no one has past immunity. This means there’s no medical way to control the spread of the disease. So, prevention and containment are the best tools we have.


Using both hygiene and physical barriers can reduce the R0 from 3 to about .6.  At this rate the infection will be reduced to a manageable level.

Hygiene protocols

  • Wash hands
  • Use sanitizer when soap not available
  • Cover your cough (mask is best)
  • Clean heavy-touch surfaces

Physical barriers

  • Quarantine
  • Social distance - 6 to 10 ft
  • Wear masks
  • Use plastic barriers
  • Avoid prolonged exposure to large groups (10+) in closed areas


A note on Political barriers - such as borders of states or countries. These are not effective methods to prevention and should not be implemented.  If one person can cross the border, then the infection can cross the border.

It's a pandemic - which means the infection has spread throughtout the world.  Containment can happen only after a reduction in the number of active cases.  So, we need these precautions as ongoing activities until there is a vaccine for COVID-19:

  • Check for symptoms (fever + cough) in people who may have been exposed
  • Test randomly and often in mobile populations
  • Implement contact tracing. Ban large gatherings since these make contact tracing impossible.
  • Continue quarantine for more vulnerable individuals
  • Apply highest cost-benefit social distancing measures
  • Explore immunity after recovery: serologic testing for antibodies 
This author describes these activities as "The Dance." During the dance there will be a number of challenges.  Here are the challenges I see:

Health Challenges

  • Invisible carriers: Asymptomatic carriers (25%?) & pre-symptomatic carriers
  • Long incubation period: 4-14 days
  • We live in a highly mobile world that affords lots of opportunity for the virus.

Information Challenges

  • Uncertainty - this is a new situation so a lot is unknown.
  • Lack of studies
  • Hard to compare with existing viruses (eg: SARS)
  • Misinformation

Challenges specific to the United States

  • Healthcare tied to employment
  • Years of erosion in the social support nets
  • Political climate
    • Distrust in government
    • Poor leadership at the national level
    • Politicians using the pandemic to their political objectives
  • Without social safety nets, the pandemic turns into a health vs economy situation, which is wrong.
  • Geographic mobility. It's possible to travel across the US without any checkpoints or borders. Also, except for Hawaii, Alaska, Puerto Rico and some other territories, not a lot of pinch points in terms of physical location

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