question: In this paper, we propose a stochastic model based on Itô diffusion as mathematical model for time evolution of new cases N(t) of the SARS-CoV-2 (COVID-19) in each day t. We propose a correspondent stochastic differential equation (SDE) analogs to classical differential equations for epidemic growing for some diseases as smallpox and typhoid fever. Furthermore, we made an analysis using the Fokker-Planck equation giving an estimating of the new cases in each day t as the mean half-width of the distribution P(N,t) of new cases. Our results display that the model based on Itô diffusion fit well to the results supported by healthy Brazilian agencies due to large uncertain in the official results and to the low number of tests realized generating so a strong randomness in the official data.