The sampling sites for nucleic acid testing are in the lateral and posterior pharyngeal wall. There are two types of samples collected for nucleic acid testing: nasopharyngeal swabs and oropharyngeal swabs, and both pharyngeal swab methods are designed to capture pharyngeal specimens. Pharyngeal Swab Sampling. The sampling site is on the lateral and posterior pharyngeal wall. Sampling method: the patient takes a sitting position, opens his mouth and makes an “ah” sound, and a sterilized cotton swab is used to collect the specimen from the lateral and posterior pharyngeal wall of the patient. Avoid contact with the tongue, oral mucosa and saliva during the sampling process to avoid affecting the test results.