Question

hhmi biointeractive
modeling disease spread

1. consider how many individuals become infected during the outbreak.

a. which curve(s) shows the number of infectious cases (i.e., infectious individuals) on a given day?
b. how could you determine how many people have been infected up until a certain point in the outbreak?
c. how many individuals were infected up until peak infection? (for example, if peak infection occurred on day 13, how many individuals in the population have been infected up to and including day 13)?
d. how many individuals were infected over the entire outbreak?

1. compare your sir graph to the example graph shown in the “summary” tab.

a. describe one difference between your sir graph and the example sir graph. what do you think caused this difference?
b. what might this mean about your population or the settings (i.e., transmission and recovery probabilities) you simulated?

Explanation:

a. In SIR (Susceptible - Infectious - Recovered) models, the 'I' curve represents the number of infectious cases on a given day.
b. One could sum up the number of new infections each day up to the certain point in the outbreak. This can be done by looking at the daily increase in the number of infectious individuals and adding them together.
c. To find the number of individuals infected up until peak infection (e.g., Day 13), sum the daily new - infection counts from the start of the outbreak until Day 13. However, without specific data from the graph or model, we can't give a numerical answer.
d. Similar to part c, sum up all the daily new - infection counts over the entire duration of the outbreak to get the total number of infected individuals.
15a. Differences could be in the peak number of infectious cases, the time at which the peak occurs, or the overall shape of the curves. Possible causes could be differences in the initial number of infectious individuals, transmission rates, or recovery rates in the simulations.
15b. If the peak is higher in one's graph, it might mean a higher transmission probability or a larger initial number of infectious individuals in the simulated population. If the peak occurs earlier, it could imply a faster - spreading disease in the simulated settings.

Answer:

a. The 'I' curve in an SIR model shows the number of infectious cases on a given day.
b. Sum up the daily new - infection counts up to the certain point.
c. Sum the daily new - infection counts from the start until Day 13 (no numerical answer without data).
d. Sum all daily new - infection counts over the outbreak.
15a. Differences can be in peak number, time of peak, or curve shape, caused by differences in initial conditions or rates.
15b. Higher peak may mean higher transmission or more initial infecteds; earlier peak may mean faster - spreading disease.