It has been estimated early on that R0 was 2.2-2.7 based on data from Wuhan which really didn’t seem right, as SARS in 2003 had a R0 of 2.75 and yet did not become a pandemic. A reminder of what R0 is:
Pronounced R-naught and known also as the basic reproductive number, it refers to how many other people will catch the disease from a single infected person, in a population that hasn’t been exposed to the disease before. If R0 is below one, the epidemic eventually peters out. Above one, it will grow, possibly exponentially.
qz.com/...
These researchers reanalyzed data from China and came up with a new estimate of R0 of 5.7 ((95% CI 3.8–8.9) in the early stages of Wuhan’s epidemic.
wwwnc.cdc.gov/…
This basically means that
1. SARS-CoV2 is much, much more contagious. (Compare to SARS in 2003 with an R0 of 2.75 and it was under control without severe Wuhan-style lockdown like in 2020) It is as contagious as the common cold, TB, smallpox and polio, but not as much as chickenpox or measles, and much more than seasonal flu.
Graph of various diseases' R0
2. It is possible to drive Rt of SARS-CoV2 <1, as in Singapore and Hong Kong, but it will take a lot of sustained control.
3. China will likely see resurgence of COVID-19 with relaxation of efforts.
4. Any premature return to normality will see a quick increase in doubling time of infections and deaths in the US.
The future is up to us. We can’t change R0, but Rt can be modified depending on our actions.
For a nice visualization with an R0 of 3, see:
www.vox.com/...