Breathing rate monitoring is a must for hospitalized patients with the current coronavirus disease 2019 (COVID-19). We review in this paper recent implementations of breathing monitoring techniques, where both contact and remote approaches are presented. It is known that with non-contact monitoring, the patient is not tied to an instrument, which improves patients' comfort and enhances the accuracy of extracted breathing activity, since the distress generated by a contact device is avoided. Remote breathing monitoring allows screening people infected with COVID-19 by detecting abnormal respiratory patterns. However, non-contact methods show some disadvantages such as the higher set-up complexity compared to contact ones. On the other hand, many reported contact methods are mainly implemented using discrete components. While, numerous integrated solutions have been reported for non-contact techniques, such as continuous wave (CW) Doppler radar and ultrawideband (UWB) pulsed radar. These radar chips are discussed and their measured performances are summarized and compared. Index Terms-Chronic obstructive pulmonary diseases (COPD), COVID-19, breathing monitoring techniques, Doppler radar, ultra-wideband (UWB) pulse radar. I. INTRODUCTIONT TE main function of the respiratory system is gas exchange. Oxygen is transferred from the external ambient into our bloodstream, while carbon dioxide is expelled outside [1]. Fig. 1 illustrates the respiratory system including the upper and lower respiratory tract regions. When inhaling, the air flow passes through the larynx and the trachea, and then splits into two bronchi. Each bronchus is divided into two Manuscript