The director general of the WHO has recently spoken of a narrowing of the window of opportunity to control the current epidemic. The tipping point – after which our ability to prevent a global pandemic ends – seems a lot closer after the past 24 hours

Prof. Paul Hunter

Professor of Health Protection
University of East Anglia
Feb. 23, 2020


The number of reports from multiple different countries in the past 36 hours showing what is most likely community human to human spread of SARS-CoV-2 confirms fears that the virus is on its way to causing a pandemic

Once the virus establishes an endemic foothold in the human population; it will become difficult if not impossible to eradicate, like other betacoronaviruses (beta-CoV) that infect humans causing seasonal outbreaks of respiratory illness, albeit of lower severity.”

Prof. Dr. Benhur Lee, MD

Professor of Microbiology
Icahn School of Medicine at Mount Sinai (ISMMS)
Feb. 21, 2020


I think it is likely we will see a global pandemic. If a pandemic happens, 40% to 70% of people world-wide are likely to be infected in the coming year. What proportion is asymptomatic, I can’t give a good number

Why do I think a pandemic is likely? The infection is in many parts of China and many countries in the world, with meaningful numbers of secondary transmissions. The scale is much larger than SARS for example (where the US had many introductions and no known onward transmission)

Why do I think 40-70% infected? Simple math models with oversimple assumptions would predict far more than that given the R0 estimates in the 2-3 range (80-90%). Making more realistic assumptions about mixing, perhaps a little help from seasonality, brings the numbers down.

Pandemic flu in 1968 was estimated to _symptomatically_ infect 40% of the population, and in 1918 30%. Those likely had R0 less than COVID-19. Below is from https://stacks.cdc.gov/view/cdc/11425

Prof. Marc Lipsitch

Prof. of Epidemiology, Harvard School of Public Health
Head, Harvard Ctr. Communicable Disease Dynamics
Feb. 14, 2020