This study shows that there is a global reduction in the fatality and virulence rate trends of the 2019-nCoV from 24 January to 06 February 2020, although the number of daily cases and deaths are increasing. In only two months, the 2019-nCoV confirmed cases exceeded the number of confirmed SARS-CoV (3.5 times) and MERS-CoV (11.3 times), although the fatality rate is currently five times higher for SARS-CoV and 17 times higher for MERS-CoV.
The initial relatively high fatality and virulence rate might be a reflex of a bias induced by the early stage of the outbreak, with more severe cases, and less implementation of health promotion and preventive measures. However, the subsequent observed reduction in fatality and virulence rate trend might be explained by: 1) increased screening capability (active surveillance for new cases and close monitoring of their contacts were implemented)  with more suspected and tested cases, thus increasing the number of 2019-nCoV confirmed cases which dilutes the increased number of daily deaths associated, 2) expansion of health care services provided by Chinese health professionals (increase in the number of quarantine sites, availability of more beds to cope with the surging confirmed or suspected cases, availability of rapid point-of-care diagnostic tests, availability of case management standard guidelines, among others), 3) highest priority given by Chinese health authorities (examples: quarantine measure adoption, build a hospital in a short time, sharing information with other countries, among others), and 4) as more is known about the virus, better are the case management capabilities. The fatality and virulence rate trend in the future is more likely to reduce as the spectrum of mild or asymptomatic infection becomes available. However, if the disease spread to low-middle income countries, with fragile health systems such as the majority of countries in Africa, the fatality and virulence rate might well increase. The future trend is uncertain, and other parameters are needed to better predict the trend.
Three major aspects might explain the spreading rate and the exceeding 2019-nCoV confirmed cases than SARS-CoV and MERS-CoV: 1) 2019-nCoV Ro (based on the estimates of Zhao et al.)  is slightly higher than those of SARS-CoV (approximately 3)  and MERS-CoV (2.7 – 3.9) ; 2) potential Super-Spreading Events (SSEs – certain individuals or situations generates extraordinarily large numbers of secondary cases) , already observed in SARS-CoV [14, 15] and MERS-CoV ; 3) the potential of transmission before the symptoms onset (from asymptomatic contacts), i.e., during incubation period ; and 4) high mutation rate which provides the possibility for the virus to adapt and to become more efficiently transmitted from person to person . In fact, the number of 2019-nCoV cases could be higher if the Chinese authorities had not been adopted restrictive preventive measures on 23 of January, such as: the suspension of public transportation, with closure of airports, railway stations, and highways in the city, among others .
The early detection and report on 31 December 2019 to WHO of a pneumonia of unknown aetiology [10, 18], with subsequent close of the seafood market (highly suspected primary focus) in Whuan on 01 January 2020, and rapidly isolation of the causative agent (on 07 January 2020) , are positive aspects that might well explain partially the relative low fatality rate of 2019-nCoV when compared with SARS-CoV and MERS-CoV. Another possible explanation is the fact that virulence is less than 20%, which means that more than 80% of 2019-nCoV cases are mild to moderate. Many other factors (discussed above) can contribute to this relative low fatality rate, and as the knowledge about the virus is increasing, multifaceted factors can be disclosure.
The analysis of only two weeks is a limitation of the study. Another limitation is the absence of data of severe SARS-CoV and MERS-CoV to compare the virulence rate with the novel coronavirus. Despite these limitations, this study (alongside with others published on novel coronavirus) provides insights for a better comprehension of the Wuhan pneumonia outbreak.