The first symptom of corona virus is the fever that is followed by dry coughing. That is the reason why the WHO said that the temperature check is effective to at least determine if the person is a potential corona virus carrier. The thermal scanner was first used in the airports for checking the arriving plane passengers. But later on the thermal scanner became a standard in stores and also in checkpoints.
However, there are the so called asymptomatic patients who are carriers of the virus but does not show any symptom like fever or coughing. They can easily escape the thermal scanner since they have no fever. And the only way to check on them is the testing kit that uses a swab or the blood testing. This goes to show that we are having a hard time in monitoring and determining the carriers of the virus hence it continues to spread.
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