On March 11, the National Health Commission announced that China has added antigen detection as an option for COVID-19 testing among the public.

Chinas National Medical Products Administration on March 12 approved five COVID-19 antigen self-testing products for sale. On the next day, five more products were approved. They will be used as supplementary to the standard nucleic acid testing to help fight the spread of the virus.  

What is COVID-19 antigen testing? How does it work? Here are several FAQs on COVID-19 antigen testing. 

(Photo: Nanfang Daily) 

Q: What is COVID-19 antigen testing?  

A: Nucleic acid testing detects RNA of the virus, while antigen testing detects virus proteins. Antigen detection can be carried out quickly in a non-laboratory environment.  

Q: Can it replace nucleic acid result?  

A: No. 

Compared with nucleic acid testing, antigen testing has the advantages of convenience and relatively lower cost. Antigen testing can facilitate the early discovery of COVID-19 cases. 

However, it is still just a supplement to nucleic acid testing for certain population, and its positive results are not conclusive for the diagnosis of COVID-19 cases. 

Q: Who should use antigen testing?  

A: *People who go to primary medical institutions for treatment, with respiratory symptoms, fever and other symptoms within 5 days. 

*Those who are under quarantine. 

*Residents who need self-testing.  

Q: How do you determine the self-test frequency?  

A: *During the quarantine period, quarantined people should take nucleic acid tests according to the COVID-19 control requirements, and take antigen detection once a day for the first 5 days.  

*Residents who test negative via antigen testing and with no symptoms may still need an antigen test or nucleic acid test when it is necessary.  

*For residents who test negative via antigen testing but with symptoms, its suggested to seek nucleic acid testing in medical institution with fever clinic.  If it is inconvenient to see a doctor, they should self-isolate at home, avoid going out, and take an antigen testing every day for 5 consecutive days.  

Q: If your antigen testing result is positive, what should you do? 

A: Report to the community, village or town immediately.  

Communities (villages and towns) will contact the emergency center to transfer suspected cases to medical institutions with fever clinics for nucleic acid testing. 

Q: How do you deal with used COVID-19 antigen testing kits? 

A: *For those who are in quarantine: gather all materials for antigen testing into sealed bags and give them to management personnel. 

*For community residents with negative test results: put all materials into a sealed bag as general waste; if the test results are positive, residents should take them to medical institutions as medical waste.  

Q: Will there be false positive or false negative antigen test results? 

A: *False positive results: low probability 

*False negative results: possible 

The sensitivity of antigen detection is lower than that of nucleic acid testing. On the premise that there is no problem with the detection reagent, as long as the antigen is tested positive, there is a high possibility that the individuals nucleic acid test is also positive, according to Cai Weiping, chief expert of the Infectious Disease Center of Guangzhou Eighth Peoples Hospital. 

Sometimes if sampling from the upper respiratory tract such as the nasopharynx and oropharynx, people may not be able to obtain pathogens, or the number of pathogens contained in the sampling is small, which may cause false negatives.  

Q: Will vaccination against COVID-19 affect antigen testing?  

A: False positives may occur in antigen testing immediately after vaccination against COVID-19. Antigen testing is not recommended within 24 hours of vaccination.  

Q: What kinds of COVID-19 antigen testing kits are available? 

A: Shenzhen Patho-Genesis (深圳华大因源), Guangzhou Wondfo Biotech (广州万孚生物), Beijing Savant Biotechnology (北京华科泰生物), Nanjing Vazyme Biotech (南京诺维赞) and Genfocus Bioengineering Tech in Beijing(北京金沃夫), Wantai BioPharm (万泰生物), Hotgen Biotech (热景生物), Bioscience (天津博奥赛斯生物), Mingdao Quick Test Biotechnology (重庆明道捷测生物), and Lepu Medical (北京乐普诊断). 

Q: Where can I purchase antigen tests?

A: A special column for COVID-19 antigen tests was officially launched on Alipay, Chinas leading mobile and online payment service. Starting from March 15, online appointments can be made to purchase antigen test products. 

At present, Alipay has cooperated with BGI, a pharmaceutical factory approved by the National Medical Administration, and a number of chain pharmacies, such as Smart Pharmacy (好药师大药房) and Kangshun Pharmacy (康顺大药房), to sell antigen tests on Alipay mini-programs. Tests from other pharmaceutical brands will be launched subsequently. 

People can search for "新冠自测" (pinyin: xin guan zi ce) on Alipay, click to enter the COVID-19 antigen test column, and make an appointment to purchase the required tests. The platform accepts pre-order of 1, 10, or 20 packages of antigen tests. Most tests can be delivered within 5 days. But due to the impact of epidemic, the delivery situation in various regions will be dynamically adjusted. 

Q: How about the price? How soon will the result be available? 

A: The price of for COVID-19 antigen self-testing is about 20-30 RMB per test. It takes about 10-20 minutes to complete testing for products from Shenzhen Patho-Genesis and Guangzhou Wondfo Biotech. 

Q: How do you collect samples and interpret results?  

A: *Open the nasal specimen collection swab (avoid hand contact with the swab head).  

*Head slightly tilted. Insert the swab slowly, 1 to 1.5 cm into the nostril and then rotate at least four times against the nasal cavity (no less than 15 seconds). 

*Test the swab as per instructions after having collected the sample. 

Source | Gdtoday