SIS model

The SIS model is a way to understand how infectious diseases spread and fade within a population. It divides people into two groups: susceptible (can catch the disease) and infected (currently sick and able to spread it). Once infected, individuals eventually recover but do not gain immunity, meaning they can become susceptible again. The model uses mathematical equations to predict how the disease will spread over time, allowing public health officials to assess control strategies. It is especially useful for illnesses where recovery doesn’t provide long-term immunity, like the common cold.