T1. Each March for the last decade, I have given a visiting lecture at @GWpublichealth "Mathematical Modeling of Infectious Disease Epidemiology", which combines my love of math w/ work relevant to my life in the #PedsICU (disclaimer: I am not an ID doc)
T2. This year unfortunately, we weren't able to find a date that worked but given the emergence of #COVID19, I thought it might be worthwhile providing a little context to some of the terms being thrown around the interwebs.
T3. "I simply wish that, in a matter which so closely concerns the wellbeing of the human race, no decision should be made without all knowledge which a little analysis and calculation can provide" Daniel Bernoulli (yes, the 0,1 guy) 1760 onlinelibrary.wiley.com/doi/abs/10.100…
T4. Glossary of terms used in infectious disease modeling: Generation time
Attack rate
Serial interval
Incubation time
Latent period
Basic reproduction number (Ro)
nccid.ca/publications/g…
Attack rate
Serial interval
Incubation time
Latent period
Basic reproduction number (Ro)
nccid.ca/publications/g…
T5. Basic Reproduction Number (Ro): The basic reproduction number (Ro) is defined as the average number of secondary cases caused by a single infectious individual in a totally susceptible population. 
T6. If Ro is less than one, then the disease can be contained; however, if Ro is larger than one, then the disease is expected to cause an epidemic.
T7. Estimates of Ro for some of the big names (#VaccinesWork) :
Seasonal influenza: 1-1.5
Small Pox: 3-7
Mumps: 4-7
Polio: 5-7
Diptheria: 6-7
Pertussis: 12-17
Measles: 12-20
Seasonal influenza: 1-1.5
Small Pox: 3-7
Mumps: 4-7
Polio: 5-7
Diptheria: 6-7
Pertussis: 12-17
Measles: 12-20
T8. While more work needs to be done to establish the true Ro for #COVID19, the American Hospital Association is reporting a best guess Ro estimate of 2.5 (see figure in T5).
T9. I will spare you all the calculus, but essentially in order to eradicate disease, the proportion of the population who are vaccinated needs to be greater than or equal to the critical vaccination coverage (Pc) (see link below for some of the math)
en.wikipedia.org/wiki/Compartme…
en.wikipedia.org/wiki/Compartme…
T10. Critical vaccination coverage (Pc) = 1 - (1/Ro)
File under: we eradicated small pox
File under: we eradicated small pox
T11. So for measles, assuming a Ro of 20, we would need - 1 - (1/20) = 0.96 - 96% of the population to be vaccinated for eradication (i.e. it's really infectious, people!)
T12. If the best guess Ro of 2.5 for #COVID19 is to be believed then 60% of the population would need to be vaccinated in order to achieve eradication. I'll let you do the math on the likelihood of this happening in the near term
T13. In the meantime, be smart. Wash your hands.
