The COVID-19 pandemic has affected the whole world and influenced almost all areas of human life. Although each country has approached the situation differently, they had one activity in common – the effort to slow down the spread of the virus to prevent an overload of national health systems. The preferred testing method for medical diagnostics as well as for elimination of the spread within the population is the Real-Time Quantitative Reverse Transcription PCR (RT-qPCR).In this book, we focus in detail on the methodology, good practice, and troubleshooting. The aim of the publication is to provide a practical advanced manual that can be utilized in any diagnostic laboratory using the PCR method.Good practice in laboratory diagnostics is essential for medical as well as for epidemiological reasons. During an epidemic outbreak, laboratory diagnostics helps physicians to treat patients effectively and the laboratory big data provides information about the spread of the virus in different sociological groups. This is illustrated in the presented experiment studying spread of the virus in a child population at schools.