(Fighting against New Coronary Pneumonia) What is an antigen test? Who does it apply to? Response from the National Health Commission
China News Agency, Beijing, March 15 (Reporter Li Chun) Recently, the "New Coronavirus Antigen Detection Application Plan (Trial)" issued by the Joint Prevention and Control Mechanism of the State Council of China has attracted widespread attention.
What is an antigen test?
Who are its users?
Li Jinming, deputy director of the Clinical Laboratory Center of the National Health Commission of China, responded in Beijing on the 15th.
On the same day, the Joint Prevention and Control Mechanism of the State Council of China held a press conference on epidemic prevention and control and vaccination.
Li Jinming said at the meeting that there are four structural proteins of novel coronavirus antigens, namely spike protein, envelope protein, membrane protein and nucleocapsid protein. The protein detected by the antigen is nucleocapsid protein, which is the N protein.
He pointed out that nucleocapsid proteins are more highly expressed and more prone to mutation.
After infection, the new coronavirus has very active replication in the pharynx. At this time, the detection of nucleocapsid protein can indirectly reflect whether the new coronavirus is infected.
Li Jinming said that there are three main groups of people applying antigen testing:
One category is those who go to primary medical institutions for treatment, such as those with clinical symptoms and fever, and those whose symptoms are confirmed to be within 5 days.
If the nucleic acid test is negative, you can stay at home and test the antigen for 5 consecutive days.
Because a person infected with the new coronavirus has a relatively high virus content one day out of 5 days, if it continues to be negative, no intervention is required.
The second category of personnel are those who are under quarantine observation, including those who are under home quarantine observation, those who are quarantined and observed when entering overseas, and those who are in close contact or sub-close contact when there is a spread of epidemics, as well as those who stay at home in closed closed communities.
Antigen is tested for 5 consecutive days, once a day. If it is positive, it may be detected. If it is negative, no intervention is required until the last nucleic acid test is performed when the quarantine is released.
A third group of people are those among the residents who wish to be tested.
If the test is positive, the nucleic acid test will be done as soon as possible. If the test is negative, you can stay at home and test the antigen when necessary.
If you have obvious clinical symptoms, especially fever, loss of taste and smell, you must go to the fever clinic.
Regarding the difference between antigen testing and nucleic acid testing, Li Jinming said that nucleic acid testing has always been the basis for determining new crown infection and is the "gold standard".
Antigen testing cannot replace nucleic acid testing.
When the antigen test result is positive, the nucleic acid test must be used for confirmation.
He explained that nucleic acid tests are 100 to 1,000 times more sensitive than antigen tests.
In addition, the specificity of the two is different. The specificity of antigen detection can reach 99%, while the specificity of nucleic acid detection method is 100%.
Recently, local clustered epidemics have occurred in many places in China, and the demand for short-term nucleic acid testing has increased.
In this regard, Jiao Yahui, director of the Medical Administration Bureau of the National Health Commission of China, said that the antigen detection application plan uses antigen detection as an important means of screening and an important supplement to nucleic acid detection, giving full play to the "early" and "early" antigen detection. "fast" advantage.
"In the first time, we can target the characteristics of asymptomatic infection of the Ormicron strain, which is relatively hidden and spreads quickly, and the use of antigen detection can screen out the possible infected people as soon as possible, that is to say, we can use the shortest It takes time to control the source of infection, and then supplemented by large-scale nucleic acid screening to improve the ability of early detection." Jiao Yahui said.
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