Is it necessary to test throat swab and nasal swab at the same time

At the press conference on the prevention and control of novel coronavirus epidemic in Beijing, Shi Guoqing, an expert from the National Health and Health Commission and deputy director of the Emergency Center of China CDC, said that oropharyngeal swab and nasopharyngeal swab are the full names of the two methods. If they are operated in a standard way, there is essentially no difference, and they are all for collecting pharyngeal specimens.

The difference is that in order to collect pharyngeal specimens, one is from oral cavity and the other is from nasal cavity, so they are called oropharyngeal swab and nasopharyngeal swab respectively.

In collecting samples of oropharyngeal swabs, the sampler can see the sampled parts, but may bring nausea, vomiting and other reactions; When sampling nasopharyngeal swabs, if the operation is standardized, the sampling throat position can not be seen, which mainly depends on hand sensory resistance, with higher technical requirements and less irritation to mucous membranes, but the public’s acceptability is lower.

Because the virus content in pharynx is affected by time and other factors, the positive rate may be affected by oral swabs, but it is not necessary to carry out the two methods together.

Then what’s the difference between the 2 methods?

Nasal swab: Put the swab into the nose and scrape it for sampling, and collect the mucous membrane or dropped tissue cells in the nasal cavity for inspection.

Throat  swab: Put the swab into the throat, gently scrape the throat at the bottom of the throat, and collect the mucous membrane or dropped tissue cells of the throat for inspection.

The difference is that when there are different diseases or conditions, there will be different infection conditions or different substances in the samples of nose and throat. Therefore, some diseases can be easily detected with nasal swabs and others with throat swabs. After that, the technical principles are basically the same. However, COVID-19 pneumonia is a lower respiratory disease, both of which are samples of upper respiratory tract, and there is no obvious difference in theory.