Originally Posted by
MickG0105 [img]images/buttons/viewpost.gif[/img]
R0 is not a necessarily good indicator of pandemicity. Measles has an R0 of 12-16, seasonal influenza has an R0 of 1.3.
https://www1.health.gov.au/internet/...models-2.2.htm
The basic reproduction number (R0) is the reproduction number
when there is no immunity from past exposures or vaccination, nor any deliberate intervention in disease transmission.
R0 is a theoretical expression of the infectivity of the organism per se. Measles virus has a high R0, hence we immunise against it and there are no pandemics (although isolated outbreaks where vaccination rates are lower). Influenza has a fairly low R0, but spreads quickly as the virus mutates (changes) each year meaning little immunity, because the vaccine is only partly protective, and because many people chose not to vaccinate.
The latest paper suggests this virus has a R0 of at least 4. That is a disaster with no immunity, and a vaccine perhaps 12 months away.
https://www.worldometers.info/coronavirus/#reproHow contagious is the Wuhan Coronavirus? (Ro)
The attack rate or transmissibility (how rapidly the disease spreads) of a virus is indicated by its reproductive number (Ro, pronounced R-nought or r-zero), which represents the average number of people who will catch the disease from a single infected person.
R0 is the number of uninfected people each infected person will infect on average. While R0 > 1, outbreak increases. Eventually something happens - quarantine, vaccine, or simply most people have already been exposed and can't be re-infected. R0 falls below 1, and the outbreak starts to recede.
A more recent study is indicating a Ro as high as 4.08.[[url=https://www.worldometers.info/coronavirus/#ref-22]22]. This value substantially exceeds WHO's estimate (made on Jan. 23) of between 1.4 and 2.5[[url=https://www.worldometers.info/coronavirus/#ref-13]13], and is also higher than recent estimates between 3.6 and 4.0 and between 2.24 to 3.58 [[url=https://www.worldometers.info/coronavirus/#ref-23]23]. Preliminary studies had estimated Ro to be between 1.5 and 3.5 [[url=https://www.worldometers.info/coronavirus/#ref-5]5][[url=https://www.worldometers.info/coronavirus/#ref-6]6][[url=https://www.worldometers.info/coronavirus/#ref-7]7]
Based on these numbers, on average every case of the Novel Coronavirus would create 3 to 4 new cases.
An outbreak with a reproductive number of below 1 will gradually disappear.
For comparison, the Ro for the common flu is 1.3 and for SARS it was 2.0.
Finally, the fatality rate for 'flu is very low - perhaps 0.01%
The fatality rate for this is at least 2%, but is almost certainly higher.
Early during an epidemic, the fatality rate is lowered by the rapid growth of newly infected people (who have not yet had time to die).
https://www.worldometers.info/coronavirus/#repro
Note that the mortality within Wahun city (the epicentre where the data is more robust as it has been going longer), the mortality is already 5.5%
During the SARS outbreak (another coronavirus), initial data suggested a mortality less than 4%. This was revised to 6-7%. Then revised to 12-14%. People remember that it ended at 12%, but forget early data suggested < 4%.
With MERS (a much smaller coronavirus outbreak), the mortality was 35%. But the current coronavirus outbreak is already orders of magnitude larger than MERS.
And that is why we have belatedly closed the border to Chinese visitors. And that is why it was too little too late