Gently prick your finger, take a drop of blood, drop it into the sample hole of the test card, and add diluent. 15 minutes later, you can judge whether you are infected with COVID-19 virus by observing whether the reaction line appears. Similar to the principle of the widely used HIV test kit, this COVID-19 antibody rapid test kit has recently become a popular choice for epidemic prevention and control in many countries.
Determine the true "penetration" of the virus
Speaking of COVID-19 test, people are most familiar with nucleic acid test as the "gold standard" for diagnosis. Nucleic acid detection is an "ongoing" detection, which detects a specific nucleic acid sequence in the virus genome by polymerase chain reaction, so as to judge whether the subject is infected with the virus at this time.
Antibody detection is a past tense detection, and IgM or IgG antibodies will be produced after human body is infected with virus. Detection of these specific antibodies in serum can determine whether the subject has been infected with the virus.
Nucleic acid detection has great limitations. COVID-19 mainly infects the lower respiratory tract, but it is sometimes difficult to detect the virus by commonly used nasopharyngeal swab sampling. Coupled with the sensitivity of the reagent itself, many countries have reported "false negative" patients in nucleic acid testing. Antibody detection and nucleic acid detection can complement each other to improve the diagnostic effect, especially to better screen asymptomatic patients.
COVID-19 is very cunning, and the hidden cases missed by nucleic acid detection will interfere with epidemic assessment and prevention and control measures. "Antibody testing can help determine the true' penetrability' of COVID-19 in the population, which is very important for understanding the true infectivity of the virus." He Dayi, a professor at Columbia University School of Medicine, said.
A few days ago, the British magazine Nature reported that preliminary research showed that the recessive cases in COVID-19 may account for about 60% of all infected cases. After asymptomatic and mild patients are cured, IgG antibodies will still exist in the body, and these infected people can be found by serum antibody detection.
Britain may become the first country to conduct large-scale antibody testing. According to the British "Guardian" report, the British government has ordered 3.5 million sets of COVID-19 antibody test kits and plans to distribute them to home isolators; In the future, millions of sets will be ordered, distributed to front-line staff and put on shelves in pharmacies and e-commerce platforms. British government officials said that antibody testing can help researchers better understand how the virus spreads by judging who is infected with COVID-19 virus and produces antibodies, regardless of symptoms.
The Spanish government also plans to carry out antibody testing in hospitals, nursing homes and other places with high risk of infection.
The Australian health department recently said that it plans to carry out antibody testing for 6.5438+0.5 million people. Larissa Labbuo, a researcher at the Institute of Molecular Biological Sciences, University of Queensland, Australia, said that antibody testing is an important means to track the real situation of the epidemic. However, it takes a week or more for the immune system to produce antibodies. Only by combining nucleic acid with antibody can we judge the infection situation more accurately.
Prepare for the "export" of epidemic prevention and control.
Many countries have strengthened the detection of COVID-19 antibody, another purpose is to identify people who have been immunized against the virus and prepare for the "exit" strategy of epidemic prevention and control in the future.
Jean-Fran? ois de Freis, chairman of the French Science Committee and former chairman of the French Medical Ethics Committee, recently said that France plans to carry out antibody testing for most people, and the number of tests can reach 200,000 to 300,000 times a day. The test results will be used to evaluate the lifting of the city blockade and carry out targeted isolation measures, and formulate subsequent "exit" strategies.
Professor Chen Baoquan, executive director of Peking University Frontier Computing Research Center, told the reporter: "The group that has been immunized is a' firewall' group." . "In the future, with the vaccine, this group will no longer have to fight."
In the opinion of many experts, identifying the immunized population through antibody testing will also provide a basis for subsequent prevention and control measures such as fine isolation and lifting the city.
Researchers at Helmholtz Infectious Disease Research Center in Germany recently said that they plan to distribute 65,438+10,000 antibody test kits to the German people in early April, and those who are positive for antibody test will get an "immunization certificate", which can release the isolation in advance. The researchers said that a large number of antibody tests will help the government determine which areas have been "group immune" and can lift the blockade.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in an interview with CBS on the 2 nd that it is necessary to look at the epidemic curve and then conduct simpler and cheaper antibody testing to determine whether the population can achieve immunity.
Larissa believes that antibody detection is faster than vaccine development, so it can also guide the direction of vaccine development. Before the vaccine is successfully developed, antibody testing can help scientists and health departments to know who is infected, who is infected and cured, and how much risk we have of being infected again.
Colloidal gold assay has been used for antibody detection in COVID-19 for 20 years. Many enterprises in China and the United States can produce COVID-19 antibody rapid detection kits. However, at present, only a few enterprises are registered for production, which cannot be compared with the mass production and use of nucleic acid reagents. Experts believe that more attention should be paid to antibody testing.
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