The COVID-19 R0 factor is 2-3, while SARS had an R0 factor of 2-5. However, COVID-19 has infected around 130,000 people and growing, while SARS totalled just under 9000 people infected.
Why is COVID-19 spreading faster and wider than SARS? What other factors have let COVID-19 reach pandemic levels, while SARS was contained and eradicated? Could the R0 factor be higher than believed? Was it initially slower to be contained?
Full disclosure, I'm not in medicine or a medical scientist. I'm a software developer and data scientist, and this has piqued my interested in the spread of infectious disease.