The Severe Acute Respiratory Syndrome Coronavirus 2 Omicron variant (SARS-CoV-2, Omicron) has been widely spread around the world. Since February 2022, Shenzhen was continuously affected by it as a major hub connecting domestic and international transportation, resulting in rapidly increasing number of infected cases.

To construct a modified susceptible-exposed-infected-recovered (SEIR) model for providing policy references and suggestions with applied value for epidemic prevention and control in Shenzhen, China, so as to alleviate the pressure of prevention and control.

This study developed a modified SEIR model targeting the epidemiological characteristics of the Omicron variant such as rapid transmission, high concealment, and general susceptibility of the population, introducing groups with policy characteristics as close contacts, secondary contacts, quarantined individuals and carriers, based on traditional SEIR model of infectious disease dynamics. The relevant parameters of the modified model were determined by fitting the Shenzhen epidemic data of February 18 to 28, 2022.

The predicted data of the model were basically consistent with the actual data from March 01 to 04, 2022, providing a reliable basis for predicting the subsequent development of the epidemic. Subsequently, the Omicron variant outbreak in Shenzhen between 5 to 19 March 2022 was forecasted through this modified model to provide guidance for epidemic prevention and control measures in terms of the degree and time of manual intervention in epidemic prevention and control, and healthcare resource requirements such as patient beds and isolation rooms.

The modified SEIR model developed in this study has proved its practical value in forecasting epidemic development, formulating and adjusting epidemic control measures, and allocating health resources.