This study is conducted by a research team from the Faculty of Engineering at Tel-Aviv University. The purpose of the study is to develop tools for early diagnosis of respiratory infectious diseases. As part of the study, data from digital questionnaires as well as usage patterns of the mobile phone will be collected. These data will be used to develop machine learning models, as well as mathematical models of infectious diseases. These models will help clinicians to improve their diagnoses, identify infections early in time, and therefore adapt the required care, allowing to prevent complications, reducing unnecessary use of antibiotics, and save costs. The collected information will be stored in a controlled and secure environment at Tel-Aviv University and will be used for research purposes only. The study has obtained all necessary regulatory confirmations including an ethical approval from the Institutional Review Board (IRB). It is important to emphasize that this study in general, and the mobile app in particular, do not replace medical consultation or treatment.