COVID Odyssey: Worldwide Winter Windup 4 ~ Is Ro 6 to 7.8 in early 2020?

For COVID-19 in early 2020, we have estimated Ro to be in the range 6 to 7.8.

For the Delta variant we have estimated Ro to be in the range 9 to 12.7.

Update. See:

COVID Odyssey: Worldwide Winter Windup 5 ~ Revised estimates for Re worldwide

We consider widening our range estimate for COVID-19 after looking at world case numbers up to 6 August 2021.

We look at the list below and consider changing the range for Ro to:

•  6 to 8 to include hopefully Turkey.
We consider this change acceptable.
• 5 to 8 to include The United Kingdom.
This estimate for COVID-19 in early 2020 is the same as the estimate for the Delta variant in the image below. We also consider this change acceptable.
• 4 to 8 to hopefully include all 31 countries in the lists below except India, Iran, and Iraq. This range may be too wide.

Which option is best? What do you think?

The estimates for the daily increase, r, are calculated using cases up to 6 August 2020.

The results are considered together with the 31 countries with over 1,000,000 cases of COVID-19 on 6 August 2021.

The lists in the tables below contain all 31 countries with over 1,000,000 cases of COVID-19 on 6 August 2021. See:

COVID Odyssey: Worldwide Winter Windup 3 ~ COVID-19 in 2020 vs 2021 ~ Cases per million people

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

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

See also:
COVIDWorldAllCasesCPM31r

COVIDWorldAllCasesCPM

COVIDWorldAllCasesCPMr

In the tables above Re#2 is an estimate for Ro, calculated using our formula for Ro:

We assume n = 10 days and that infectivity decreases daily at a rate of 1/r.

In the table below, if n > 10 days, the values for Ro are likely to be too big.

We have used simulations in Excel to create the formula. See:

COVID Odyssey: Winter Windup 14 ~ COVID-19 ~ Simulations to develop our formula for Ro

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).

We have also used this version:

Note:

• Ro = 8 corresponds to r = 1.52, near the r = 1.5 estimated for China, The USA, and South Korea.
• Ro = 6 corresponds to r = SQRT(2), near the r = 1.4 estimated for New Zealand, Italy, France, Norway, and Poland.

For r = SQRT(2), Ro = 6.0 (1 dp), we may have case numbers doubling every two days.

For r = SQRT(3), Ro = 12.7 (1 dp), we may have case numbers tripling every two days (for the Delta variant).

For the Delta variant, we have estimated Ro to be in the range 9.0 to 12.7 (1 dp).

Also see:

COVID Odyssey: Worldwide Winter Windup ~ COVID-19 in 2020 vs 2021 ~ How many people may one person infect in your country?

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

The image below shows previous estimates for Ro.

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