We revisit the simulations undertaken in early 2020 to estimate the number of people one person with COVID-19 may infect on average over an n-day infectious period.
We developed a formula calculating the numbers Ro and Re (with and without isolation respectively) given a daily rate (r) of increase in cases. We also produced a summary table showing values produced by the formula.
For definitions and the table, please see:
COVID Odyssey: Winter warning ~ Summary 2020 revisited ~ Daily cases and how many people one person may infect on average? – COVID Odyssey by Alan Grace: My vir[tu]al COVID-19 journey (wordpress.com)
The simulations each generated 40 sample spreads of COVID-19 with the means for each and the overall means and other stats for the samples.
We found that a daily rate r = 1.4 worked well in New Zealand. We used this in the simulations and also r = SQRT(2) [~1.4142].
Some simulations using n = 10 resulted in values close those calculated by the formula (see the table).
We assume infectivity decreases daily by a factor of 1/r.
The results for sample runs are shown below for the above values for r (only the first 30 values are shown; mean (mu) on the top line is the value calculated by the formula):
More complete results are in the PDFs below:
Below is the formula again and the table: