The Internet has become an essential part of our daily life. It has fundamentally changed the way we live, interconnecting people at a virtual level in a variety of ways, ranging from professional life to social relationships. The next technological mega-trend of the Internet is the Internet of Things. It uses networking and ubiquitous computing to upgrade physical objects to be intelligent objects .Medical care and smart healthcare systems can be considered one of the most interesting application fields of the Internet of Things. The IoT revolution is reshaping modern healthcare systems by incorporating technological, economic, and social Prospects. It is evolving healthcare systems from conventional to more personalized healthcare systems through which patients can be diagnosed, treated, and monitored more easily. Since the end of 2019, the world has been facing the threat of COVID-19 pandemic. Controlling and managing this virus can be achieved with the aid of smart healthcare systems based on Internet of Things technology. This will also help in slowing its spread through early detection, prediction, and monitoring (tracking) of new cases. This paper surveys the most fundamental concepts of new technologies such as fog computing, cloud computing, and the role of IoT-based technologies in COVID-19. It also discusses the definition, the characteristics, the main goals, and the overall vision of smart healthcare systems.