The CoVID-19 and flu are both respiratory infectious diseases, with similar symptoms including fever and cough, but they aren't the same.
Both the CoVID-19 and flu are diseases caused by a virus. In the case of flu the pathogens (病原体) are flu viruses, and for COVID-19, it is a novel coronavirus (新型冠状病毒).
Common symptoms for flu and novel coronavirus are nearly identical-fever, cough and tiredness sometimes sore throat and diarrhea. In several cases they result in pneumonia（肺炎）and even death in the worst cases. Flu has seasonal ups and downs. Although it can exist all year round, the virus infects more people in winter and spring. As for the novel coronavirus, the median age for the infected is 51. But the novel coronavirus is a brand new virus no one has total immunity no matter their age.
Both the flu and the novel coronavirus are transmitted in the similar ways, by direct contact with infected patients or small droplets from the nose or mouth when a person with virus coughs or breathes.
FIu can be spread by an infected person for several days before their symptoms appear. As for the novel coronavirus, spread might be possible before people show symptoms, but this is not thought to be the main way the virus spreads.
For the novel coronavirus, there is also a risk for aerosol transmission (气溶胶传播) In health facilities, people may catch the virus if they breathed in aerosol, the suspension of find solid or liquid particles in the air, which have been contaminated by the virus. The novel coronavirus has also been found in patients' fecal (排泄物) samples, but fecal-oral transmission does not appear to be a major transmission route.
