We revise our estimates for Ro worldwide.
Previously we had the ranking below (see r1 and Re1 columns) for the 2020 outbreak:
The above was calculated using:
Note that n = 10 days and r[d] is a daily rate of increase (growth factor) calculated over the next 5 days starting on day d for each country, and C[d] is the total number of Cases on Day d of the outbreak.
The calculation for r gave equal weighting to r[d] and r[d+1]. i.e. 0.5 weighting for both.
We have discovered that for the Delta variant weights of 0.25 and 0.75 give better results for New Zealand. See:
The revised calculations are (only the line with the weights has changed):
This produced the following new ranking (see the r2 and Re2 columns):
The PFS below are more extensive and may be easier to read:
We note that the values for r1 and r2 may not always occur on the same day. See:
Look at the last two columns which correspond to r1 and r2. Also see:
We note that New Zealand now has a new value of r = 1.400890.
We have seen that r = 1.4 fits New Zealand data well in the early 2020 outbreak:
China now has a new value r = 1.500985. This is very close to what we have estimated (r = 1.5):
We recommend using the new calculation weights and new ranking.
Note that our estimate for Ro ranging from 5 to 8 in the original 2020 COVID-19 outbreak has not changed.
Our estimate for Ro for the current Delta variant outbreak ranging from 9 to 12.7 also remains unchanged.