The only reliable way of collecting samples is with nasopharyngeal swab. (See  diagram).

This is supported by physiology. The pharynx is the section where the conditions for spreading of the virus are ideal. This is why from the very beginning samples were collected from the nasopharynx.

It is therefore evident, that the first 2 cm of the nostril are not as representative as the nasopharynx, the swab needs to reach the back of the nasopharynx for the sample collection. The timing of the sample in the buffer fluid is critical and is done automatically within the Mass testing system. No clocks or timers are required, thus eliminating all human error.

99.9% accuracy is guaranteed.