The population is generally susceptible to novel coronavirus pneumonia, while infection is more severe in the elderly and those with underlying disease, and also in children and infants. Pneumonia from novel coronavirus infection can occur in both immunocompromised and immunocompetent populations and is related to the amount of exposure to the virus. If exposed to a large amount of virus at one time, the disease can develop even if the immune function is normal. Therefore, the elderly are not more susceptible to novel coronavirus infection, but whether or not they get sick is related to the amount of virus they are exposed to at one time. Therefore, regardless of the type of population, avoiding disease endemic areas and crowded places and taking good personal protection can effectively prevent infection.