Camera stream processing is a popular and quick way to detect objects. Human behaviors and actions can be detected as objects from the video frames using a trained deep learning model. For the detection of risky behaviors such as coughing, hugging, handshaking, and doorknob touching, the You Only Look Once version3 (YOLOv3) which is suitable for real-time behavior detection for online video streams, was trained and applied [63,64]. This library classifies and localizes detected objects in one step with a speed of faster than 40 frames per second (FPS). We considered two main types of risky behaviors for COVID-19 indoor transmission: Group risky behaviors (e.g., hugging) and individual risky behaviors (e.g., coughing). Figure 12 illustrates how to train a model for COVID-19 transmission risky behavior detection using YOLOv3.