This article describes the understanding of COVID-19 here at Camp Dismal. It is an attempt to help my readers understand the dynamics of infection spread and protective practices.
For authoritative answers to common questions, please consult the following websites having researched verified information about the disease.
- https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub WHO public information portal.
- https://www.cdc.gov/coronavirus/2019-ncov/ US CDC public information portal. May be tainted by US politics.
- https://coronavirus.jhu.edu/map.html Johns Hopkins University tracking site.
- https://www.vdh.virginia.gov/ Virginia health department tracking site.
- https://en.wikipedia.org/wiki/Mathematical_modelling_of_infectious_disease A run through the math of disease spread
- https://youtu.be/gxAaO2rsdIs A wonderful video showing the form of the model, simulation runs of the model, and how public actions affect model parameters and the spread of the disease.
These are the key takeaways of a retired engineer with extensive experience developing nuclear power plant behavior simulations. The equations describing epidemic spread point dynamics are very similar to those describing nuclear reactor thermal neutron population point dynamics. In the COVID-19 equations, the delaying parameters are days rather than seconds as with delayed neutron emission in a reactor.
- Sorry, there are no silver bullets or magic elixirs to prevent or cure COVID-19.
- Infected population doubling time is an indication of the effective encounter probability of infection transfer, Rzero. Increasing Rzero decreases the doubling time.
- Doubling behavior of the solution causes rapid runaway of the infected population: 1, 2, 4, 8, 16 … to 4 billion after 32 doubling times. This is why it is important that we behave in a manner that reduces the rate of encounters between susceptible and infected individuals and the probability of virus transmission on encounter.
- Group behavior can speed or slow the spread of the disease through the susceptible population.
- You can be infected without being aware that you are. A significant fraction of cases on USS Harry Truman are minor or asymptomatic.
- You can shed virus in infectious amounts before presenting symptoms or while infected but asymptomatic. There is a time window of 3 or so days where this is happening in a case that later exhibits symptoms.
- Presence of an individual with a silent infection at an event of an hour or so duration will cause a significant number of attendees to become infected. Mass transit, church, eating and drinking establishments, etc are high risk environments for spreading the infection.
- Wearing a surgical mask reduces the rate of emission of infectious particles by an asymptomatic infected individual.
- Wearing a surgical mask may reduce the rate at which a susceptible individual is exposed to infectious particles but is a secondary objective of mask wear.
- Increasing exposure duration increases the probability that an exposed susceptible individual will become infected.
No it is not the flu
Reports from recovered COVID-19 patients makes it clear that COVID-19 is not just another flu or childhood disease. The articles I have read in New York Times describe a disease that causes far more damage than mumps, measles, German measles, or chicken pox. The COVID-19 virus causes significant lung damage and can also damage liver, kidneys, heart, and blood vessels which shed clots that cause heart attack and stroke. The pain described is reported as being far worse than that I remember from my encounters with the childhood diseases.
- You can get seriously sick.
- You can have lasting organ damage.
- You will have a lengthy recovery.
- You may not fully recover.
- You may not recover.
Don’t be taken in by a low case count in your community
If you visit reference you will see a map of Virginia showing the number of cases reported in each political entity in Virginia. Showing counts, it looks as if the countryside is only moderately affected. Switching to cases per 100,000 tells a different story. Many small counties have a higher rate of infection than Norfolk and Virginia Beach.
The normalized rate matters, not the community total. The normalized rate reflects the likelihood of encountering an infected individual as you go about your essential activities.
Do wear a surgical mask
Wearing a mask is important in two ways.
- If you are infected, it slows the rate of release of infectious particles into the environment around you. This is an important measure for reducing the spread of the infection.
- By wearing a mask you show that you understand the factors promoting infection, that you are aware that you can be a source of infection before having symptoms, and that mask wear shows that you are acting to minimize the likelihood of infection of those you encounter before you know you have the disease.