Background Having a minimum number of workers in medical services is widely regarded as a key component of disease prevention. However, with the delay in confirming cases of SARS-CoV-2, the understaffed medical providers informed late and the virus has rapidly spread nationally. Methods This study, based on the Dempster-Shafer theory method and Evidential Reasoning, assesses the risks posed by understaffing for the SARS-CoV-2 outbreak. Results The findings examine six (6) factor risks and show that the understaffing risk in 2019 was 0.14% in magnitude in Wuhan, compared to 0.27% in Shenzhen. When ranking understaffing risks from low to high, the findings show that they increased from 3.979 to 3.983% and from 3.998 to 4.002% in Wuhan and Shenzhen, respectively. Conclusions We first conclude that from the SARS-CoV-1 to the SARS-CoV-2 outbreak, understaffing risk equally increased at 0.004% in both cities. However, Shenzhen city is at a higher risk than Wuhan city. Second, Shenzhen understaffing delayed SARS-CoV-2 outbreak prevention 0.13% more than Wuhan city. We generally conclude that Shenzhen city could be doubly worse off than Wuhan city if it was the epicenter of the SARS-CoV-2 outbreak. Therefore, public health care training and employment policy must be optimized to complete the lack not only in both cities but also in other cities to prevent future outbreaks.