In the global COVID-19 epidemic curve before the Opmi-Krong pandemic, the highest figure was 900,000 per day; recently, this figure has exceeded 3 million, and there is still no downward trend.
In the United States, in response to the surge in the number of People Infected with Omikejong, the Biden administration is buying 1 billion sets of rapid test kits and distributing them to the public free of charge starting this month.
This antigen detection method, which was judged to be "useless" in the early epidemic, was quickly widely recognized after the Opmi kerong pandemic, and the huge demand for testing was released.
Eight o'clock Jianwen learned that the average price in Australia rose from $10 to $20-30.
Image from Visual China
A person in charge of an antigen reagent foundry in Hangzhou told Eight Points Jianwen that a kit with a cost price of 1 to 3 yuan is difficult to find in Australia, and the highest price has been speculated to 2300 yuan.
The Spring Festival is approaching, temporary workers are in short supply, and packagers can't recruit people for 300 yuan a day. "There are too many orders in front, there is an epidemic around the factory, and it is necessary to isolate at every turn." The factory faces a bunch of customers, orders from other countries, all lined up until the end of the year. ”
China's dynamic zeroing strategy is still based on nucleic acid test results as the "gold standard", therefore, the new crown antigen test is a business that is only externally inward, the huge supply and demand gap has opened the door to overseas markets for enterprises that have laid out antigen testing in the early stage, and Jiuan Medical, which won the "New Year's Eve Demon Stock", created a legend of 28 ups and downs in 50 days before and after being approved to enter the US market.
A number of staff engaged in the production and export of new crown antigen testing products told Eight Point Jianwen that overseas orders have long been queued up for years, "do not worry about buyers, inkblot orders, all do not pick up", foreign trade merchants "urgently seek spot exports", and even some international students have also started to buy on behalf of the business.
In December, Jiuan Medical submitted the "Proposal on Using Family Self-Test Boxes to Achieve 1+1 Covid-1 Epidemic Prevention in Aomi Kerong" to the Tianjin Municipal Epidemic Prevention and Control Command, hoping to pass the emergency approval of Jiu'an Medical's "iHealth New Crown Self-test Box" and put it into Tianjin as soon as possible to block the first line of prevention and control of the spread of Aomi Kerong, but the proposal has not received a clear answer so far.
At present, there are only 3 approved antigen detection reagents in mainland China, and all of them are used for professional testing.
With the global popularity of antigen self-test, more and more international students and overseas Chinese share their antigen self-test process on various social media, and many people can't help but wonder when they see the "Made in China" marked on the product packaging:
Home express tests are popular overseas, why is it useless in China? Can antigen testing supplement or even replace nucleic acid testing in China? Two years after the COVID-19 epidemic, why didn't the frequency and scale of testing decrease but increase?
Two models, which is better or worse?
The advantages and disadvantages of nucleic acid testing in China and the rapid testing that is currently prevalent in most countries, that is, antigen testing, are obvious.
Virologist Chang Rongshan explained to Eight Points That in principle, the nucleic acid detection course covers a long distance, and the sensitivity is significantly higher than that of antigen detection at any time during the virus shedding process.
However, antigen detection is convenient, low cost, and can be sampled at home, the results can be produced in 15-20 minutes, and the risk of mobile transmission can be greatly reduced with home isolation.
Why is antigen detection, which was previously questioned by scientists for its low sensitivity, suddenly gained popularity?
"At present, the new coronavirus in Europe, America, Australia and Japan and other regions is still in large-scale epidemic, limited by manpower, material costs and other factors, nucleic acid detection capacity can not meet the needs of epidemic prevention and control", Shenzhen National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital President Lu Hongzhou believes, "foreign control measures for new coronavirus patients are mainly home isolation, therefore, antigen detection has become their main means of detection."
"This is in line with their prevention and control policies, goals and medical and health system, and the nucleic acid testing model is undoubtedly the most suitable testing strategy for China's current national conditions," Zhao Dahai, a professor at the School of International and Public Affairs at Shanghai Jiao Tong University and executive director of the Shanghai Jiao Tong University-Yale University Joint Health Policy Research Center, told Eight Points.
Whether overseas countries retreat due to insufficient nucleic acid testing capacity, or actively explore the "coexistence with the virus" method and choose antigen detection, at present, the world has formed two completely different screening models with nucleic acid detection as the core and antigen detection as the core, the former represented by China, the latter represented by the United Kingdom and Singapore.
In China, the infected people will eventually be detected by nucleic acid testing - the inbound personnel must undergo intensive nucleic acid testing, the infected people scattered in the crowd will also be captured by the nucleic acid detection system of fever diagnosis, gathering activities and travel requirements, and many cities have added "sampling" to key groups on the basis of regular nucleic acid screening. Round after round of large-scale nucleic acid testing is also needed to screen out all infected people.
Matching this sensitive screening system is the "unified management model", that is, once the infected person is found, the government will organize centralized isolation and centralized treatment until the epidemic is completely cut off and reach "dynamic clearance", in addition, the mainland has also set up a set of social operation system based on nucleic acid testing, and travel, gathering, and organizational activities are based on negative nucleic acid testing.
In the United Kingdom, the discovery and treatment of new crown infected people are "self-help mode", Liu Min, an international student who was infected with the Delta variant strain in July last year, told Eight Point Jianwen that in the United Kingdom at that time, residents who had paid medical insurance could book a free test package, and people who had positive antigen self-tests, close contact and symptoms could book nucleic acid testing to the NHS, and there were two modes of nucleic acid testing and sampling, one was to mail the test kit to sample itself, the other was to take the initiative to test the testing agency, and the time difference between the two results was one day.
However, Liu Min and her boyfriend, who have already developed symptoms, have repeatedly tested negative results, and finally can be diagnosed by nucleic acid testing. After the diagnosis, the two self-isolated at home, took medication, and judged the condition by monitoring blood oxygen and antigen. The NHS will provide some remote guidance but it will not be meaningful, and after completing the 10-day home isolation, the NHS reminds that "even if there are mild symptoms, you can wear a mask to enter and exit public places without the presence of mild symptoms" after completing the 10-day home isolation.
After the arrival of the "milder" Omilon, this "home self-test + home isolation" model is more mature, on the basis of the previous, in December 2020, the United Kingdom shortened the general isolation period from 10 days to 7 days, and in January this year, the United Kingdom announced that asymptomatic infected people who tested positive for quick testing could directly start home isolation without being diagnosed by PCR testing.
This means that asymptomatic or mildly infected people are no longer the focus of surveillance, and infected people voluntarily report antigen-positive test results, and there is no difference in the final recovery without testing or reporting.
Nucleic acid testing capacity is not up to standard, fast testing is one step behind the United States in the face of a surge in opichron cases also began to accelerate the supply of antigen testing reagents, January 14, the White House announcement showed that the Biden administration is buying 1 billion home rapid test kits, this month plans to provide 500 million copies, this new plan will allow each American family to carry out 4 free self-tests. At the same time, pharmacies, community health centers, schools, and private insurance companies have also begun to supply testing.
In addition, European countries, Australia, Japan, India, Indonesia, Australia, Israel, etc. have or are promoting antigen testing in China, and the United Kingdom, Singapore, Brazil, France, Italy, etc. have taken antigen test results as one of the entry criteria.
Why doesn't China do antigen testing?
The reason for the huge difference in Chinese and foreign screening methods is that the overall prevention and control strategies of various countries have different requirements for screening.
According to several experts, the current sensitivity and specificity of antigen detection are not enough to meet the requirements of the "dynamic clearance" strategy.
Virologist Chang Rongshan explained to Eight Points That nucleic acids are very easy to detect in the first three days of infection, but antigens are difficult to detect. This means that very early infections are unlikely to be detected by antigen testing. Within 3 to 7 days of infection, antigen testing is more sensitive.
A WHO document mentions that when the COVID-19 prevalence rate in the community is 1%, even if the test with a specificity of 99%, the positive predictive value is poor because half of all positive results are false positives.
Foreign countries are in the stage of pandemics, so the accuracy of antigen testing will be much higher than in China.
In addition, under the domestic dynamic zeroing epidemic prevention policy, a series of problems such as follow-up certification and isolation brought about by antigen testing are also quite tricky.
Zhang Hongtao, an associate professor at the University of Pennsylvania School of Medicine, believes that antigen testing is a theoretically advantageous test method and has not been adopted by China. One of the important reasons is that the results of the antigen test report have not been officially recognized, and the accuracy and sensitivity of the home test have yet to be confirmed. If these issues are not resolved, do they need to be quarantined if the self-test results are falsely positive? Is the entire community going to be closed?
"China's existing nucleic acid testing system has been very convenient, rapid and complete, relatively speaking, the number of infected people is relatively small, and the demand for antigen detection is not large." Zhang Hongtao said.
Moreover, the current cost of nucleic acid testing is not high, in August last year, the results of the joint collection of new crown detection reagents in the four provinces of Beijing, Tianjin, Hebei and Lu were released, of which the price range of single nucleic acid kits was 5.38-24.9 yuan.
However, in community screening with very low positive rates in China, the sensitivity differences of various detection methods will be reduced. Chang Rongshan believes that if only a single detection method is used, there is a systemic risk of missed testing.
Omikeron with increasingly frequent testing
Since October 2021, in large-scale outbreaks in Xi'an, Henan And other places, the number of nucleic acid tests has become more and more frequent, often taking off in 10 rounds.
The completion of large-scale nucleic acid testing in just a few days has also become an unbearable pressure on the grassroots. Cases of emergency training of sampling personnel, inadequate operation leading to missed inspections, and even transmission at detection points occur from time to time.
In order to improve the efficiency of screening and reduce costs, nucleic acid testing has been expanding from single detection, 5 mixed 1, to 10 mixed 1, and the mixed sample volume has been expanding. Recently, the National New Crown Epidemic Prevention and Control Command issued a document again, requesting the promotion of "20 mixed 1" nucleic acid testing.
"The sensitivity of 20-mixed 1 is 1/20 of that of a single test. In the face of Thermokeron, where the viral load is lower, weak positives close to the threshold of yin and masculine are more difficult to find. Jin Dongyan, a virologist at the University of Hong Kong, told Eight Points.
On the whole, in the detection process, the emergence of Omiqueron has challenged all detection methods, including antibody detection: the Omilkeron variant strain has strong transmission, mild symptoms, accelerated intergenerational transmission, and vaccines have changed the response process of viruses and human immunity, which has increased the complexity of detection and the risk of missed tests.
In this sense, the difficulty of catching infected people is systematically increasing, and all screening strategies need to be more frequent and precise than in the Delta era to maintain the same protective barriers.
China's "dynamic zero clearance" strategy has higher requirements for testing, eight points of health news learned that on the basis of nucleic acid testing in key populations ranging from 1-3 times a week, random sampling has been added in some areas, and China as a whole bears heavier input pressure, from the input end to the end, nucleic acid testing will only do more and more.
The increase in the amount of testing means that the cost of epidemic prevention is increased. Eight points of health news learned that at the end of this year, due to the epidemic of Omike rong, many counties and cities and even township hospitals have also set up new nucleic acid testing points, a sales staff in Shandong told eight points of health, this year's nucleic acid testing consumables and equipment sales into the fourth quarter to usher in a turnaround, the current sales of small secondary hospitals with high sales of standard testing program hardware equipment overall price of more than one million.
In addition, at present, the sampling of large-scale nucleic acid testing in the mainland is mainly undertaken by medical personnel, and the fatigue of personnel and the decline in specimen quality are practical problems that have to be considered.
Chang Rongshan, a virology expert, believes that the nucleic acid detection reagent itself is no problem, but the sampling site is not uniform and the sampling method is not standardized, which will cause a significant decrease in the sensitivity of the nucleic acid screening system. If you operate in accordance with national norms, there will be the best detection effect, in principle, in the control area does not need multiple rounds of full nucleic acid, only 2-3 rounds can be tested for all positive.
Lu Hongzhou reminded that the best specimen sampling area for nucleic acid testing is sputum, followed by nasal swab, and again throat swab, for those non-severe patients with a disease course greater than 8 days, the use of throat swab samples alone for virus screening is more likely to have a false negative.
Chang Rongshan also believes that for Omi Kerong, home antigen detection, if it is positive, the probability of a good product detected at one time is more than 60%, and the antigen detection with home isolation can greatly reduce the risk of mobile transmission.
On January 15, the medical treatment team of the joint prevention and control mechanism of the State Council issued technical specifications and began to implement the "20 mixed 1" type nucleic acid mixed detection technology.
"With the increase in the scale and frequency of screening at present, the main reason for the increase in the number of mixed tests is also to improve the efficiency of screening and control the cost of screening," Lu Hongzhou told Eight Point Jianwen, "20 mixed 1 is more suitable for large-scale population nucleic acid screening work." Of course, in this process, it also puts forward higher requirements for the renewal of our mixed sampling tubes and the pretreatment of samples by nucleic acid test personnel before nucleic acid extraction."
If Omikeron is not the end, then high-frequency detection will not stop for the foreseeable future.
Written by Yu Huanhuan and Shi Chenjin
Chen Xin 丨 is responsible for editing
This article was first published on the WeChat public account "Eight Points Health" (ID: HealthInsight)
Respect the original copyright, unauthorized reproduction shall not be reproduced, infringement responsibility at your own risk
![Exploring headlines| the terminator of cancer? Therapeutic tumor vaccines turn "terminal diseases" into chronic diseases[fig]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)