Not sure about that. A low oxygen saturation rate (hypoxemia) would indicate lung disease and lung inflammation is already present. Someone with COPD, for example, might be fine but have a low blood oxygen level when measured with a pulse oximeter. Personally, temperature screenings would be a better measurement because one of the first signs of SARS-Cov-2 infections is a temperature of 100 degrees (38 celsius), though the latency period of this infection does not cause a temperature spike until a fews days have passed with someone who has the disease. Unfortunately, only a vaccine (or vaccines) will be the safe path to future travel.