Then according to the above assumptions, set the basic infection rate of individual contact with the object S, then the probability of the individual being infected when contacting the door at time t is
Then, according to the above hypothesis, if the basic infection rate of the individual in contact with the object is s, the probability of the individual being infected when contacting the door at time t is
Then, according to the above assumption, assuming that the basic infection rate of an individual contacting with an object is S, the probability of an individual being infected when contacting with a door at time T is