Questions and Answers | What used to be “Yang” has become “Yin”! Will there be reinfection within the family? What’s the deal with “nucleic acid positive, antigen negative”? – Mobile Xinmin.com

“The first group of colleagues who passed positive became negative and positive again. Is it repositive or secondary infection?” “Will the positive infections in the family cause mutual reinfection?” Am I yin or yang?” Recently, the discussion of “yin and yang” has become a hot topic in Moments, which often confuses people…

Dr. Ai Jingwen, Department of Infectious Diseases, Huashan Affiliated Hospital of Fudan University, told reporters that first of all we need to understand that Fuyang and reinfection are two different concepts. The first means that the infected person has two positive results in the same cycle of infection, usually when the second positive result is detected he is no longer contagious, while the second means that the infected person has experienced two different cycles of infection and the time of second infection. Spans are often longer, which is contagious.

Some netizens had a bar on the antigen after the infection, but two bars were detected after a few days. Is it the second infection or Fuyang?

Ai Jingwen said the first possibility is that sampling in the previous test was not in place, so the previous test showed a false negative; the second possibility is that the residual fragments of the virus in the body are excreted from the body one after another, then the antigen will be positive again. However, according to past experience, most of these Fuyang people have been detected because some residual fragments of the virus have been detected, and there will generally be no reinfection to others. Of course, there is a third possibility, which is that the patient is actually positive for the virus again in a short period of time, but this type of situation often occurs in patients with obvious immunodeficiency such as tumors, and rarely occurs in people with good general health.

The virus spreads very quickly in the same household, especially in a household with a large population. Will there be repeated infections after one round of infection?

Ai Jingwen pointed out that positively infected people generally do not get reinfected within a short period of time after the antigen becomes negative. If co-residents are infected within 1 to 2 weeks, there will be virtually no cross-infection or repeat infection during the recovery period. However, if you encounter a high-risk infection environment again one month after turning negative, the chance of reinfection will gradually increase, but in general, the chance of infection will increase significantly after 6 months or more. For young to middle-aged adults, symptoms of secondary infection are often milder than the first; but for older adults with vulnerable immune systems, secondary or multiple infections require closer health monitoring and prompt symptomatic treatment to further reduce the risk of progression to serious disease.

“Nucleic acid positive, antigen negative”, many friends have encountered this kind of problem, what’s going on?

There are many reasons for this contradictory result. Ai Jingwen said that the sensitivity of antigen detection is generally believed to be relatively low, and can only be successfully detected when the virus content in the body is relatively high. Therefore, the antigen detection may not be able to detect positive in the early stage of the infection and late healing. This is why some patients are antigen negative on the first day of fever, but are antigen positive on the second day. Also, since antigen detection can be performed by anyone, the accuracy of test results also depends on whether or not sampling standards are in place and how standardized the operation is. Of course, false positives can also occur in nucleic acid tests, which is also related to contaminated reagents.

At this stage, when more and more people around are infected, instead of obsessively chasing test results and clarifying “yes or no”, it is better to pay attention to your symptoms. When you have been in contact with a positive infection, or even have symptoms of fever, cough and sore throat, it is significant to get the antigen test done at this time. If you have symptoms, and the antigen test is positive again, there is a high chance you are infected; if you have related symptoms, but the antigen test is negative, if you don’t have to, you don’t have to go all the way to finding a nucleic acid point for a nucleic acid test to prove you are “positive”. You just need to treat the symptoms according to your situation, then do the antigen or nucleic acid test as needed after the symptoms disappear.

Also, since new crown is a self-limiting disease, mild and asymptomatic patients do not need to take antiviral drugs. Of course, because the new coronavirus is very contagious, if you have a fever and suspect that you are infected, then even if you cannot be sure for the moment, you should also pay attention to isolation as much as possible, especially if there are elderly people at home. In any case, protecting the elderly will be the top priority in dealing with the peak of the first wave of the epidemic. (Xinmin Evening News reporter Zuo Yan)