# 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:
owid-covid-data.xlsx
retrieved 7 May 2020 from
https://github.com/owid/covid-19-data/blob/master/public/data/owid-covid-data.xlsx

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:

Source:

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.

cf:

See:

https://www.bbc.com/news/health-57431420

Note:

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:

https://aaamazingphoenix.wordpress.com/?s=windup

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