COVID Odyssey: Winter Windup 12 ~ Conclusion~ Ro = 6 to 7.8 in early 2020?

We revisit data for the spread of COVID-19 in early 2020.

We see in China that a daily increase close to r~ 1.5 fits the case data well from 23 Jan to 28 January 2020.

We have seen in New Zealand that a daily increase close to r~ 1.4 fits the case data well from 16 to 26 March 2020.

For definitions look at the bottom of this post.


Source file:
retrieved 7 May 2020 from

Note: Case numbers have been updated from the values in the above table.

We conclude that r ~ 1.51 will provide a good value to calculate Ro using China case numbers.

From the table below we see that for r = 1.51, Ro ~ 7.8.


In New Zealand we have already seen that r = SQRT(2) works well and gives R0 ~ 6.

We conclude that in early 2020 Ro is likely to be in the range 6 to 7.8.

Also see:



The above graph was obtained from this article: taaa021 (Click to view PDF):
The reproductive number of COVID-19 is higher compared to SARS coronavirus
published 13 February 2020, obtained from here:
(Journal of Travel Medicine, Volume 27, Issue 2, March 2020)

We have already estimated Ro for the Delta variant to be between 9 and 12.

This may suggest that Ro for the Alpha variant may be centred around 8.4; maybe in an overlapping range of 7.4 to 9.4.





By definition we let:

  • r denote the effective Reproduction rate of COVID-19 for one day
  • Ro (R0; R-Zero; R-Nought) denote the Reproduction number for COVID-19 without any quarantine or isolation
  • Re denote the effective Reproduction number for COVID-19
    (Re assumes isolation/quarantine is happening)
  • case be defined as a person diagnosed as having COVID-19

Note that Ro and Re are numbers (not rates), the number of people one person with COVID-19 may infect on average without quarantine or isolation (Ro) and with quarantine or isolation (Re).

Also see:

Shared Posts (Pingbacks)

3 Comments Add yours

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s