# Category: Epidemic Models

## Epidemic Models 1, Part 5

David A. Tanzer, July 26, 2020

# The SIR model (cont’d)

Last time, we introduced the SIR model, and looked at the formula for one of its reactions, recovery. Here we complete the effort, by looking into the more complex reaction, infection.

SIR-network

## The infection reaction

Recall that the recovery reaction has the formula:

$$\mathrm{Infected} \xrightarrow{\mathit{recovery}} \mathrm{Recovered}$$

The infection reaction has more arrows connecting it to the compartments than the … Read more

## Epidemic Models 1, Part 4

David A. Tanzer, July 18, 2020

# The SIR model

Last time, we introduced the general idea of reactions. Now we turn to the SIR reaction network, which is a fundamental model:

SIR-network

Footnote: such diagrams are called ‘Petri nets’, after Carl Petri, who invented them in 1939, at age 13, to describe chemical reactions. They are now more widely applied.

Here we see that the three compartments are represented … Read more

## Epidemic Models 1, Part 3

David A. Tanzer, July 18, 2020

# General idea of reactions

Last time we surveyed some compartmental models in epidemiology. Now it’s time to look deeper, as the compartments are only part of a model.

The models also contain reactions, which connect the compartments and cause them to change over time; they are processes which ‘stir’ and transform the contents of the compartments. A reaction proceeds in small steps. In … Read more

## Epidemic Models 1, Part 2

David A. Tanzer, July 10, 2020

# A menu of compartmental models

Last time, we talked about the idea of compartmental models, where the population is divided into compartments like Susceptible and Infected. If these are the only compartments, the model is called SI. But SI is very simplistic, and cannot express things like recovery, immunity or death.

Richer models are obtained by introducing more compartments.