# COVID Odyssey: Winter Windup 7 ~ COVID-19 Delta Variant 2021 ~ Simulations

In the previous post we saw that for the Delta variant there could be a daily increase in the number of cases of r = SQRT(3). For background see:

COVID Odyssey: Winter Windup 6 ~ COVID-19 Delta Variant 2021 ~ Does Ro = 12?

This would give rise to the table below: We see from the last row that we need to generate around 1.77 million cases for each simulation with 9 or 10 columns for each case requiring a spreadsheet with over 16 million non-empty cells.

We assume that there is a “gap-day” for incubation for each new case before each case infects other people, essentially giving an incubation period of 48 hours (2 days).

We assume that infectivity of each case decreases daily at a rate of 1/r: We use random numbers to choose the day a case is infected using the last column above.

From the previous post we expect Ro, the number of cases one person may infect (with no isolation or quarantine) to be around 12.7 (1 dp) for an infectious period of n = 10 days.

For each new case on Day 12, we count up the n umber of people infected by each case.

Below are the results from some simulations:    The results help validate the formula we use:   