Recently, the State Food and Drug Administration approved a number of new coronavirus antigen detection reagent products. On Friday (March 18), the first batch of new coronavirus antigen detection reagents in the Beijing market went on sale, which also made home-based self-testing of the new crown virus a reality. What exactly is antigen testing and can it replace nucleic acid testing? What should members of the public pay attention to when self-testing?
Antigen detection kits are available in Beijing
At 5 p.m. on March 18, Mr. Liu, a citizen, walked into a pharmacy in Jianwai Street, Chaoyang District, and after registering his personal information, he spent less than 25 yuan to buy an antigen test kit.
Mr. Liu: "These days I see on the Internet that there seems to be students in Zhejiang who are already using it, so I also come to the pharmacy to buy a try, because this kind of self-complete operation, the time is also very fast, I still think it is quite convenient." ”
The kit purchased by Mr. Liu is a "new customer" on the shelves of major pharmacies in Beijing recently. On March 11, the National Health Commission issued the "Application Plan for Antigen Detection of the New Coronavirus (Trial)", which clearly adds antigen detection as a supplement to nucleic acid testing.
Notice on the issuance of the application plan for antigen detection of the new crown virus (trial implementation) / source from the website of the National Health Commission
As of the evening of March 18, the State Food and Drug Administration has approved 17 new coronavirus antigen detection reagent products for listing. Soon after the antigen detection kit was approved, e-commerce platforms such as Meituan Buy Drugs and Dingdang Fast Drugs have taken the lead in selling, followed by offline pharmacies.
The e-commerce platform has launched antigen detection kits/journalist mapping
On March 18, the reporter visited more than 10 well-known chain pharmacies in Dongcheng, Xicheng, Chaoyang and other places, half of which said that the kits had arrived for sale, and some also asked to register personal information at the time of purchase.
Reporter: "When did this start selling?" ”
Clerk: "It was yesterday." ”
Reporter: "How much is it?" ”
Clerk: "24 blocks 8 a box." You need to register your personal information to purchase. ”
Reporter: "Can the results be transmitted to my health treasure after buying?" ”
Clerk: "No. ”
Antigen detection kit sold by a pharmacy in Beijing/photographed by a reporter
In street interviews, most of the public took a wait-and-see attitude towards such products.
Citizen: "If its accuracy rate is not high enough, I still have to perform nucleic acid testing, I think this is a waste of my time and energy." The second is that if it is more troublesome to use, I think I may still choose nucleic acids, because it is convenient to detect nucleic acids now. ”
Citizen: "The key depends on its effect and whether it is recognized, for example, if the government recognizes this thing, then of course it is suitable for buying it at home." If you say you can't go out of town, you can't take the car, it's useless. And the other one also has to consider its cost, if it is cheaper than nucleic acid testing, then of course buy this. ”
Can antigen testing replace nucleic acids?
Antigen detection is not a new technology, this detection method is essentially carried out on a test strip by antigen and antibody binding reaction. Antigen detection reagents for various pathogens such as Helicobacter pylori and hepatitis B virus can be purchased on the market. Zhang Wenhong, director of the National Center for Infectious Diseases, once described antigen testing as "clothes" worn outside the virus in an interview with the media.
Zhang Wenhong: "Antigens are like the outer clothes worn by the virus, and nucleic acid is the gene inside the virus." The detection method of antigen is to detect this 'clothing' from the existing antibody, synthesize the specificity, and show it. Nucleic acids are to be amplified, and once amplified, their sensitivity increases. ”
A picture to read the new crown virus antigen test / from the People's Daily
The reporter purchased an antigen detection kit from the pharmacy, washed his hands according to the instructions, and began to test.
Reporter: "The first step is to turn on the single-use sampler. Now I am putting the sampler into the nasal cavity about 1.5 cm, turning the left and right nasal passages 4 times each, this time I can control the force by myself, which can reduce the uncomfortable feeling that others bring when they are operating. Now the swab head needs to be soaked below the level of the sample extract for at least 30 seconds and squeezed at least 5 times. I opened the antigen detection card again, which has 1 letter C and 1 letter T on it. I was constantly dripping the reagent extraction solution of the test onto the test card, and I could see that in less than 5 minutes, a small red bar appeared at the position of the letter c of the test card. 15 minutes have passed and the test results have not changed, which means that my test results are negative. If there is a small red bar in both the letter C and the letter T, this requires caution, it may be infected with the new crown virus. ”
Items in the antigen test kit/reporter shoot
Schematic diagram of antigen self-testing process / from the website of the National Health Commission
Compared with nucleic acid testing, antigen detection is more convenient and faster, and it can also reduce the risk of contact with infected people during the process of queuing up to detect nucleic acids. So can it replace nucleic acid testing? At a press conference on the joint prevention and control mechanism of the State Council held on March 15, Li Jinming, deputy director of the Clinical Laboratory Center of the National Health Commission, said that nucleic acid testing is still the "gold standard" for determining new crown infection.
Li Jinming: "The specificity of antigen detection can reach 99%, but the specificity of nucleic acid detection is 100% in terms of methodology, that is, the nucleic acid detection has no false positive in methodology, and what you do is real." So nucleic acid testing has always been a basis for us to determine the new crown infection, a 'gold standard', so antigen detection can not replace nucleic acid testing. When the antigen test is positive, be sure to confirm with a nucleic acid test. But the nucleic acid test is positive, whether your antigen test is negative or positive, the person being tested must be treated as a new crown infection or confirmed patient to take measures.
Antigen testing is mainly suitable for three types of people
According to the "Application Plan for Antigen Detection of the New Coronavirus (Trial)", antigen testing is mainly applicable to three types of people, one is to go to primary medical and health institutions for treatment, accompanied by respiratory, fever and other symptoms and symptoms within 5 days; the second is to isolate and observe personnel, including home isolation observation, close contact and sub-close connection, entry isolation observation, sealing and control area and control area of personnel, the third type of community residents with antigen self-testing needs. Li Tong, chief physician of the Department of Respiratory and Infectious Diseases of Beijing You'an Hospital, once believed that the use of antigen detection will help further improve the ability to "detect early" the epidemic.
Li Tong once said: "In some grass-roots institutions or remote areas and other places, once an epidemic occurs, it may take a long time to carry out nucleic acid testing. If an antigen test is done on key groups immediately before the nucleic acid test, it will probably be able to find out the infection situation, reduce the risk of spreading around when the infected person goes to line up to do the nucleic acid, and avoid more people being infected. Another example is our sealing area, which may have to carry out multiple rounds of full nucleic acid testing in the past, and with this antigen detection, the frequency of nucleic acid detection can be reduced, and the antigen detection in the middle is used as a supplement. ”
Some provinces and cities have carried out antigen testing
Recently, there have been clusters of epidemics in many parts of the mainland, and the situation of epidemic prevention and control is grim and complex. Changchun, Jilin and Hangzhou, Zhejiang and other places have successively carried out government-led antigen testing. Ms. Zheng, a resident of Shige Community in Zhongtai Street, Hangzhou, received a free antigen test kit from the street on the afternoon of March 15.
Ms. Zheng: "The government service personnel came to each of our homes to do it, did it in front of them, they helped us check it, upload it immediately, do it at 3 p.m., and the health code at seven or eight o'clock in the evening is displayed, which is concise, convenient, and fast."
Residents of Hangzhou conduct antigen testing/ from the Central Broadcasting Network
Jilin launched the new crown antigen self-test reporting function / from the network
At the press conference on the prevention and control of the new crown pneumonia epidemic in Beijing held on the afternoon of March 19, Li Ang, deputy director of the Municipal Health Commission, suggested that those entering (returning) to Beijing and those in the health observation period should conduct antigen self-testing.
Li Ang: "For those who have completed isolation observation and are under health observation, it is recommended to conduct antigen self-testing during the interval period of nucleic acid detection. For those entering (returning) to Beijing, it is recommended to conduct antigen self-testing as soon as possible after entering (returning) Beijing, and complete nucleic acid testing within 72 hours according to the time limit requirements. For those who have recently purchased "four types" drugs and have 11 types of symptoms such as fever to visit primary medical institutions, it is recommended to conduct antigen self-testing within 72 hours. ”
What should I do if I test positive for antigen?
For residents who test for antigens at home, what should be done once they test positive? Jiao Yahui, director of the National Health Commission's Medical Administration Bureau, said at a press conference on the joint prevention and control mechanism of the State Council held on March 15 that once the self-test is found positive, it is necessary to report to the local community in a timely manner.
Jiao Yahui: "Residents test their own antigens at home, if they are positive to report to the community in the jurisdiction, the community notifies the emergency center to call 120 special ambulances, and the patients who test positive for antigens are transferred to a medical institution with nucleic acid testing conditions for nucleic acid testing." Reminder to residents who are tested at home, once they are positive for antigens, all used swabs, test tubes, and test cards must be packed in sealed plastic bags and treated according to medical waste. ”
The staff checked the antigen testing products sold by the pharmacy/sourced from the Fengtai District Government Weibo
Li Tong, chief physician of the Department of Respiratory and Infectious Diseases of Beijing You'an Hospital, also suggested that publicity, guidance and management should be strengthened for citizens who purchase antigen testing products at home.
Li Tongzeng: "How to manage this part of the public should be paid attention to at home, and we may also have to consider whether he will not report a person who tests positive for antigens? This requires us to refine the plan in the future, such as doing some reminders when selling test kits, and positive must be reported. If you don't report it or say that the positive one has gone out on its own, it should be restrained by legal responsibility. ”
The emergence of antigen detection can move the threshold of "early detection" of the epidemic forward, saving a lot of time, manpower and material resources for follow-up accurate prevention and control. However, it is mainly used in high-risk, high-prevalence cluster infection populations, nucleic acid testing is still the basis for the diagnosis of new crown virus infection, so the public does not have to compete for the new crown antigen self-test box, and there is no need to hoard goods.
Reporter Chen Changsong Editor Sun Yuan Editor Cheng Yan