The differential equation is the most powerful platform in mathematics and is useful in engineering and science disciplines. The use of different calculus can significantly predict the world around us. Differential equations are used in various fields, such as biology, economics, physics, chemistry, and engineering. They can describe rapid growth and decay, population growth of organisms, or changes in investment returns over time. Among these models, delay models are well known for virology analysis and predicting disease transmission, which controls infection. To define four population spatial evolution: easily unaffected, untreated infections, treated infections, recovered, and to develop a strategy of factors affecting the human body delay differential equation (DDE) is used. In this paper, we review some mathematical modeling that interprets viral discrimination with the influenza virus. Examples are used to predict some solution measures to underline and apply DDE to model infectious diseases. This study provides a wide range of factors that play a role in mathematical models of epidemiology and public health policy. This study is helpful for those who are interested and help the fieldworkers to learn about it. We discuss delay models using differential equations to measure the spread of viral diseases. The disease control predictions discussed may be helpful for more projection.