The 2019-nCoV epidemic continues. During the past month, huge progress has been made in pathogen monitoring, identifying sources, basic etiology, clinical treatment, drug testing, and vaccine development. With the efforts of China and the helps of other countries in the world, we hope that the epidemic will subside soon. Future research on viral replication, pathogenesis, antiviral drugs and other aspects of 2019-nCoV will contribute to the treatment and prevention of the virus. However, given the emergence of 2019-nCoV pneumonia as a new infectious disease with interspecies transmission from animals, we should reflect on the origin of the human pathogen and learn from our experience. With changes of ecology and human activities, including unlimited invasion of natural habitats of animals, consumption of some of these animals, and modern agricultural practices, the spillover of viruses from natural hosts to humans continues to appear and may even be escalating. Although we have built an unparalleled human civilization and a highly developed information society, invisible viruses can still have devastating effects on human beings. The high lethality viruses such as SARS-CoV, MERS-CoV, H5N1, H7N9, Ebola and emerging 2019-nCoV should serve as an alarm to the world. We should strive to reduce the probability of their occurrence and harm. Strengthening the investigation of animal etiology, normalizing the storage of high risk pathogens, reducing direct contact with wildlife, maintaining the barriers between natural reservoirs and human society and completely eradicating wildlife trading will help to achieve these goals.