Since the end of July, COVID-19 has been scattered everywhere. Universal COVID-19 nucleic acid detection has been opened in many parts of the world. After several rounds of nucleic acid sampling and testing, many citizens have some doubts. What are the differences between nasopharyngeal test and oropharyngeal swab sampling?

• What are the ways of sampling the nucleic acid of the SARS-CoV-2?

nucleic acid samples collected through the nasal cavity are called “nasopharyngeal swabs”. Samples collected through the mouth are called “oropharyngeal swabs”. Both are the main ways to collect samples from COVID-19 nucleic acid detection. In addition, there are deep expectoration fluid, nasopharyngeal or respiratory tract extract, bronchial lavage fluid, and alveolar lavage fluid.

• how to choose nasopharyngeal swabs and oropharyngeal swabs?

Whether to choose nasopharyngeal swabs or oropharyngeal swabs, mainly follows the following principles: first, according to the eighth edition of the prevention and control plan and the second edition of COVID-19 nucleic acid testing manual, the first choice is to collect nasopharyngeal swabs while collecting nucleic acid samples. Secondly, asymptomatic infected persons, entry personnel and close contacts should collect nasopharyngeal swabs during isolation observation; Third, due to the relatively simple operation of oropharyngeal swabs, more oropharyngeal swabs should be collected when nucleic acid detection is carried out in low-risk areas.

• why should nasopharyngeal swabs be collected first?

The study shows that the detection rate of COVID-19 nucleic acid in nasopharyngeal swabs is higher than that in oropharyngeal swabs, because the nasopharyngeal cavity is relatively closed and the virus is easier to accumulate. Secondly, the sampler can stand behind the patient’s side. The patient only needs to expose his nostrils, and there is basically no pharyngeal reflex. The exposure risk of the sampler is lower and safer than that of the oropharyngeal swab. However, whether it is oropharyngeal swab or nasopharyngeal swab, the key is that the collection action should be standardized, in place and meet the standards. As long as the collection is standardized, both methods can achieve the expected detection purpose.