An epidemic has changed the world. Throughout the world, governments of all countries are facing huge challenges in epidemic prevention and control. During the COVID-19 pandemic, China is in the four stages of the prevention and response framework (prevention, detection, control and The key to success is shown in the treatment). And through the media and medical assistance to spread China’s experience to the world. However, due to many reasons such as religion, democracy, regional habits, and virus mutations, the global epidemic has not been well controlled, and the number of confirmed cases and deaths has increased significantly.
After entering March 2021, the global epidemic that was originally gradually stabilized, because of the time bomb in India, it exploded again! By the way, the global new crown has been brought into the third wave of pandemic. According to information released by the World Health Organization, since the beginning of April, the number of new cases in India has risen almost linearly, and it has officially exceeded 400,000 on the 26th local time. And with a total number of confirmed cases of 1.838 million, it became the second most affected area in the world after the United States.

But this is not all cases, because the positive rate of testing has also risen sharply, reaching 20.3% as of April 26. This means that the infection has increased. On the premise that the number of people tested has not increased, a very large number of infected people have no chance of being diagnosed. The data currently exposed is only the tip of the iceberg.

The pandemic of the new crown virus has always been the sword of Damocles hanging over people’s heads, and what can effectively stop the pandemic is detection. The new crown test originally used the molecular technology platform to detect the nucleic acid of the virus, but now it is slowly changing to use the colloidal gold platform to detect the antigen protein of the virus. What matters is the real demand of the market.
The history of changes in global new crown testing
Nucleic acid detection era
The COVID-19 pandemic has been around for more than a year, and the WHO research report stated that it will continue to disrupt basic health services in 90% of countries. No matter how advanced and developed countries are, the public health care system and expert scientific institutions that have been built before have only contributed to the early success. Competent countries such as the United States, Germany, and Italy have invested huge financial expenditures in square cabin hospitals, The molecular laboratory was built to improve detection capabilities, adopted effective containment strategies among the elderly, and effectively utilized sufficient hospital capabilities. However, with the surge in the number of patients and the full spread of the new coronavirus, the capacity of the hospital has been overloaded.
Developed countries are too busy to take care of themselves, while developing countries are even more constrained by national financial reasons and unable to conduct timely universal testing. WHO provides them with technical support, virtual training, equipment and supplies to improve testing capabilities around the world. For example, when COVID-19 first appeared, Somalia did not have molecular testing capabilities, but by the end of 2020, Somalia has 6 laboratories that can perform such testing.
However, this still cannot meet the goal of everybody’s thorough examination. At this time, the disadvantages of nucleic acid detection appear:

*The cost is huge-the high cost of laboratory construction, personnel training, laboratory equipment, testing reagents and consumables. These costs have already stretched the medical systems of many developed countries, and low- and middle-income countries cannot afford them.

*The operation is complicated and takes a long time. Although the POCT molecular laboratory has already appeared, the average time for the conventional RT-pcr molecular laboratory to produce results is about 2.5 hours, and the report basically has to be obtained the next day.

*The laboratory’s geographic location is restricted and cannot cover all areas.
*Increase the risk of infection-on the one hand, the medical staff performing the test will increase the risk of infection, and laboratory contamination will also turn other samples into false positives and cause panic; on the other hand, people have to go to the hospital to perform accounting tests. Virtually increased contact with patients with positive or incubation period, and the risk of infection in healthy people is also increasing.

The short era of antibody testing
In fact, in the early stages of the epidemic, everyone was trying to reduce the cost of COVID-19 testing, as well as simplifying the testing methods as much as possible to reduce the workload of medical staff. Therefore, antibody testing is the fastest detection method that can be implemented on the colloidal gold platform. pregnancy. But because the antibody test is a serological immune response after the human body is infected with the new coronavirus, the immunoglobulin IgM antibody appears first, which is produced in about 5 to 7 days; then, IgG antibody appears, which is produced in about 10 to 15 days. Under normal circumstances, IgM antibodies are produced early. Once infected, they are produced quickly, maintained for a short time, and disappear quickly. A positive blood test can be used as an indicator of early infection. IgG antibodies are produced late, last for a long time, and disappear slowly. A positive test in the blood can be used as an indicator of infection and previous infections.

Although antibody detection solves some of the disadvantages of nucleic acid detection, it takes a certain incubation period for the antigen to enter the body before IgM and IgG are produced. During this period, IgM and IgG cannot be detected in the serum, and there is a window period. Antibody detection should be used for supplementary testing or combined nucleic acid testing for suspected patients with negative nucleic acid test results.

As the purity of the antigen raw materials reaches the standard and the production capacity is in place, antigen detection has begun to be widely used because it is the same as nucleic acid detection for detecting new coronavirus pathogens and there is no window period.

Antigen detection (Professional Use) era

After several outbreaks and mutations of the new coronavirus, it may become a virus that coexists with humans for a long time like the flu. Therefore, the new crown antigen test products have become the “new favorite” of the market because of their easy operation, quick results, and low price. For product performance testing, only CE certification is required at the beginning. Later, European countries have gradually adopted the new crown antigen test as a preliminary screening method, and the product performance has been strengthened. The medical and health departments of Germany, the United Kingdom, Belgium, Switzerland and other countries have introduced the first Tripartite laboratories verify the product performance of various manufacturers around the world and give special approvals

▼German Bfarm Special Approval Part Screenshot
▼German PEI
▼Belgium rapid antigen test (professional use) special approval section screenshots
Of course, the detection of new crown antigens can actually be implemented on two platforms, one is immunochromatography, which is what we usually call colloidal gold, which uses gold particles to wrap the antigen antibody; the other is immunofluorescence, which uses latex. Microspheres encapsulate antigen and antibody. Compared with immunochromatography technology, the cost of immunofluorescence products is higher.

1. An additional fluorescent reader is required for interpretation.

2. At the same time, the cost of latex particles is more expensive than gold particles

The combination of Reader also increases the complexity of the operation and the rate of misoperation, which is not so friendly for ordinary users.

Colloidal gold new crown antigen detection will eventually become the most economical choice in the market!
Author: Do Laimeng K