any device that accumulates health-related information about people via phones, smart wearable devices, bands, implanted surgical instruments, or other portable devices that can monitor health.  
The IoT is used in hospitals and households to remotely monitor patients. By recognizing and treating hazardous illnesses and issues at an early stage, remote patient monitoring in the healthcare sector may dramatically minimize needless visits to medical professionals, hospital stays, re-admissions, and medical care expenditures [7]. Currently, our healthcare system is very expensive due to the patient's hospitalization until treatment duration. Smart technology that can remotely monitor patients can help solve these challenges. The Internet of Medical Things (MIoT) reduces healthcare costs by gathering and exchanging real-time patient health data with clinicians. This enables the treatment of health issues before they become major illnesses [8]. The MIoT will undoubtedly improve people's quality of life. Integrated tool development can result in a variety of useful enhancements in integrated information system services, system processing, and communications with a wide range of control. As a result, in the realm of healthcare, multiple IoT-based digital, wearable devices and applications (as depicted in Figure 1) are required to identify, track, and prevent various chronic and viral illnesses [9].  
Wearable devices are one of the most important IoT technologies in the present era [10]. Wearable devices are at the center of every conversation in IoT-related healthcare systems, as they have the potential to bring about a major transformation. They are also seen to be the ideal strategy for monitoring, tracking, and detecting chronic and viral illnesses in the healthcare sector. Wearable devices, which are considered an essential aspect of the IoTs, let patients get the proper medical care at the right moment [11; 12]. They have the potential to transform the standard of human existence in the current era in ways that cannot be achieved exclusively through smartphones, and customers have shown a strong desire to purchase and wear these devices. In hospitals, medical equipment along with the medical staff deployment can be tracked by IoT devices with sensors [13; 14]. These devices are extensively employed in the healthcare industry to monitor patients and produce alerts for individuals who have dangerous conditions.  
In the last two decades, researchers have invented various wearable devices that can monitor vital health constraints such as pulse rate, breathing, blood pressure, lungs sound,  
Figure 1: Applications of Internet of Medical Things (IoMT).  
body actions, temperature, etc., as shown in Figure 2. Due to the variety of wearable devices in the market for monitoring different health parameters, it is difficult to select the appropriate smart wearables from the market. Hence, there is a real need to investigate the existing wearable in terms of their performance and identify their discrepancies. Therefore, in this paper, the authors aimed to focus on and discuss the most trending wearables in the medical field for the purpose of detection and prevention of multiple diseases. A comparison of the most widely available wearable devices for monitoring the vital health signs of humans and infectious diseases such as COVID-19 is carried out in this paper [15; 16; 17; 18; 19; 20]. Moreover, the importance of improved healthcare services due to IOT technology is highlighted. In Section 2, the different IoT healthcare applications are explored. Smart wearables for healthcare are presented in Section 3. Section 4 presents the challenges and issues related to smart wearables devices, followed by the conclusion in Section 5.