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We draw conclusions from our previous posts based on cases up to August 6 2020.
We have already looked at worldwide estimates for Ro if Ro ~ exp(2.5r – 2.5), Ro ~ exp(sr – s), and Ro ~ exp(tr – t) where Ro is the average number of people that one person with COVID-19 may infect over a ten-day infectious period.
We have already considered the following:
The purple curve in the graph below shows our estimate for Ro:
The graph is based on this data:
We have already looked at worldwide estimates for Ro if Ro ~ exp(2.5r – 2.5), Ro ~ exp(sr – s), and Ro ~ exp(tr – t) where Ro is the average number of people that one person with COVID-19 may infect over a ten-day infectious period.
This PDF contains more countries:
We conclude that up to 6 August 2020:
- For all countries Ro was below exp(2.5r – 2.5) and above exp(2.2r – 2.2) .
- Ro was estimated as being exp(tr – t) in the above table.
- We estimate r using r* calculated as an average over a two day period.
- Where a weighted average gives a very different estimate, further investigation may be required.
- Only Iran had a value for r* around 1.6 where r* is our estimate for r, the daily increase in case numbers early in the 2020 outbreak.
- For Iran Ro was estimated at 4.4
i.e. One person could infect 4.4 other people over a ten-day infectious period. - For all other countries Ro was no higher than 3.5
- For New Zealand r was around 1.4 and Ro was around 2.5
- For New Zealand we have the following case numbers:
We see r = 1.4 is appropriate up to the day after lockdown on 25 March 2020. - Over 50 Countries have a value for Ro at least 2.0 and over 60 countries had a value for Ro over 1.9 with over 40 countries with Ro from 2.0 to 3.0
- Eight “countries” had insufficient case numbers to estimate Ro:
- We also note the following information from the literature:
According to a recent review, by Park et al., the mean R0 range is from 1.9 to 6.5 based on eight published and eight preprint papers. Of 20 estimates, 13 studies were in the range of 2 and 3. The estimates are comparable to that of SARS-CoV in the early phase of an outbreak in Hong Kong (2.7) and Singapore (2.2–3.6). See:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7751056/
In the article below of 21 estimates for the basic reproduction number ranging from 1.9 to 6.5, 13 were between 2.0 and 3.0:
- Estimates for Ro assume there is no natural immunity. This makes New Zealand (where I live) being a small relatively isolated country in the south pacific region a good candidate for estimating Ro. For New Zealand r was around 1.4 early in the 2020 outbreak and Ro was around 2.5 (see#8).
- Also see:
Green Bottles, Alan's Ark & COVID Odyssey: Alan Grace's vir[tu]al journey 