What does COVID-19 antigen testing mean? What is the difference with nucleic acid testing?

On March 23, after review by the National Medical Products Administration, two new coronavirus antigen detection reagent products were approved. We all know that nucleic acid testing is an important means of diagnosing the new coronavirus. So, you may wonder what the new coronavirus antigen test means? What is the difference with nucleic acid testing?

1. What does the coronavirus antigen test mean?

The new coronavirus antigen test is conducted on a test strip through the binding reaction of antigen and antibody. It is convenient and quick, and the results are usually available in 15-20 minutes. However, the antigen-antibody reaction may result in false positives due to some interference, and the methodological specificity cannot reach 100%.

2. What is the difference between coronavirus antigen testing and nucleic acid testing?

1. Antigen testing is to detect the virus envelope; while nucleic acid testing is to detect the RNA substance in the nucleus.

2. The advantages of antigen testing are that it is simple and rapid, with results available in 10-15 minutes. Individuals can do self-tests, which is conducive to early diversion and rapid management of suspected populations. The disadvantage is that its sensitivity is slightly lower and not as high as nucleic acid testing. However, nucleic acid testing requires special instruments and can only be operated by professionally trained personnel. It takes a long time to obtain results, at least 2-3 hours.

At present, nucleic acid testing is still the basis for confirming new coronavirus infection, and antigen testing can serve as a supplement to nucleic acid testing. If the nucleic acid test result is positive, regardless of whether the antigen test result is positive or negative, corresponding measures should be taken in accordance with the new coronavirus infection or confirmed patients with new coronavirus pneumonia; if the nucleic acid test result is negative, but the antigen test result is positive, it will be regarded as a new coronavirus infection, and close observation will be carried out through centralized isolation and other measures, and continuous nucleic acid testing will be carried out. A positive antigen test result cannot be used solely as the basis for determining new coronavirus infection.

3. Which groups of people are suitable for the new coronavirus antigen test?

According to the "New Coronavirus Antigen Detection Application Plan (Trial)", there are currently three groups of people who are eligible:

The first category is people who go to primary medical and health service institutions for treatment, accompanied by respiratory and fever symptoms, and whose symptoms have appeared within 5 days.

The second group is people under quarantine and observation, including those under home quarantine and observation, close contacts and secondary close contacts, people under entry quarantine and observation, and people in closed and controlled areas.

3. People who need antigen testing. If residents have symptoms such as fever or cough and are worried about being infected with the new coronavirus, they can conduct self-testing.

In general, due to the slightly lower sensitivity of antigen testing, it is mostly used for testing high-risk, high-prevalence clustered infection populations. The general population should not do antigen testing at will, and antigen test results cannot replace nucleic acid test results.