Asymptomatic infection means that the organism is infected with a certain pathogen, such as bacteria, viruses, etc., but without any discomfort and clinical symptoms. Confirmed infection means that the organism is infected with a certain pathogen and has developed clinical symptoms. Whether or not clinical symptoms appear after infection with a pathogen and the severity of clinical symptoms are related to the amount of the infecting pathogen, the physical condition of the infected person, and whether or not prophylactic vaccination has been carried out, among other factors. In general, the chances of developing asymptomatic infection are higher when the number of pathogens attacking the organism is small, and when the infected person has been vaccinated or is in good physical condition. On the other hand, people with a large number of pathogens, who have not been vaccinated and who are in poor health or have other underlying diseases are more likely to develop a confirmed infection.