The nasal swab should ideally be able to poke in about 5 to 10 cm. This is determined by the length of the nasal passages of the pairs of collectors. If infected with respiratory viruses, especially the new coronaviruses that are prevalent in the current epidemic, these viruses can parasitize the nasal mucosa, especially the posterior wall of the nasopharynx. If a specimen is collected at this time, it is best if the nasal swab can penetrate about 5 to 10 cm deep, reach the posterior wall of the nasopharynx, stay for about three seconds, gently rotate, and then the collection is successful. Some people are short, the nasal cavity is relatively short, the depth of this poke into the short; if the height is taller, the general depth will be a little longer. Nasal swab nucleic acid collection generally need professionals to collect, so as to improve the success rate, improve the positive rate, to avoid the occurrence of missed diagnosis, generally need to undergo standardized training to be able to go on duty.