The peak of "two positives" is coming? Professional interpretation of the nine high-frequency issues of the new crown

Recently, many of my friends have tested positive for COVID-19 twice. Topics such as "the darker the color of the antigen test, the more serious the disease", "the symptoms of positive test are mild, so positive test is definitely not serious", and "since positive test is positive twice, there is no need to get the COVID-19 vaccine" have sparked discussions. For this reason, NetEase Health specially invited Chen Meifang, deputy chief physician of the Department of Infectious Diseases of Peking University People's Hospital, to answer questions for everyone.

1. NetEase Health: In the COVID-19 antigen test, does the darker the color of the T zone mean the more serious the disease?

Chen Meifang: Not necessarily.

First of all, you should understand that the color depth of the T zone may indeed have a certain correlation with the viral load in the sample collected this time, but it does not necessarily represent the actual viral load in your body. Because there is a possibility that you may not have collected enough samples, or that you are still in the early stage of the disease, if this is the case, it cannot truly represent the current condition of the disease and its future progression.

In addition, each person's response to viral invasion is different. Some people with lower viral loads can also cause stronger immune responses and more severe clinical manifestations. Therefore, the depth of the color of the T zone of the antigen test cannot be used to judge the severity of clinical symptoms.

You should also note that different brands of COVID-19 antigen detection reagents have different T-zone colors due to different color developers. Currently, most COVID-19 antigen detection reagents use the colloidal gold method, and the color of the T-zone is orange or purple.

2. NetEase Health: If the same person undergoes nasopharyngeal and oropharyngeal swab tests at the same time, will the color of the T zone be different?

Chen Meifang: The colors should not be much different.

The main strain currently in circulation is the Omicron strain. Compared with previous strains, its replication in the upper respiratory tract is significantly enhanced, and the virus can proliferate in large quantities in the nasal and pharyngeal cavities, so the viral load in the nasopharynx and oropharynx is similar. If everyone uses the same sampling method and the sampling is in place, the color of the T zone measured by the nasopharyngeal and oropharyngeal swabs should be similar in depth.

3. NetEase Health: Is it correct to say that “as long as there are symptoms, the antigen test will be positive”?

Chen Meifang: Incorrect, not necessarily.

First of all, the "antigen" in the antigen test mainly refers to the nucleocapsid protein in the virus, namely the N protein. Only when the virus reaches a certain load can it be detected. In the early stage of the disease, the viral load is not high enough and it is likely that it cannot be detected**. **Therefore, some people have already developed related symptoms, but the antigen test results are still negative.

If some patients have a negative antigen test result in the early stage of the disease and their condition is critical and it is urgent to determine whether they are infected with the new coronavirus, a more sensitive nucleic acid test can be used to assist in the judgment.

Studies have shown that the positive detection rate of COVID-19 antigen in symptomatic patients is 60%, while that in asymptomatic patients is 12%. Antigen testing generally has the highest positive rate within one week of onset, and generally begins to show positive results on the 2nd or 3rd day. Therefore, multiple COVID-19 antigen tests can be performed in the early stages of the disease for early diagnosis and treatment.

Although antigen testing is not as sensitive as nucleic acid testing, its simplicity, convenience, speed and low cost are its great advantages and it deserves widespread adoption.

4. NetEase Health: If someone tests positive again within a week after the antigen turns negative, is this considered "re-positivity" or "secondary infection"?

Chen Meifang: A positive antigen test result within one week after turning negative does not constitute “re-positivity” or “secondary infection”.

Generally speaking, it is impossible for the human body to completely eliminate the virus within one to two weeks after being infected with the virus. In the case of "antigen turns negative and then becomes positive again within a week", the "negative" may be due to inadequate sampling or low viral load, resulting in a false negative. The positive result after another test shortly thereafter is the true condition of the body.

It is recommended that everyone conduct another antigen test 1 to 2 days after a negative result in the antigen test at the end of the disease to ensure the accuracy of the test.

5. NetEase Health: "If one positive symptom is mild, two positive symptom will not be serious." Is this statement scientific?

Chen Meifang: It’s not scientific, not necessarily.

The severity of symptoms is mainly related to the amount of virus that enters the human body and the body's resistance. The human body and the virus are like a balance. If the number of viruses that enter the human body is low and the toxicity is low, and the body's own resistance is relatively high, then the balance will lean towards the human body's resistance, and the symptoms may be relatively mild, or even asymptomatic.

If the virus that infects you this time is highly virulent and a large number of them enter the human body, and you happen to be busy, stressed, and have poor sleep during this period... resulting in a low resistance level, the symptoms will be more serious.

6. NetEase Health: “I have experience with the second time Yang, so I don’t need to go to the hospital and I can cure it myself.” Is this idea correct?

Chen Meifang: This idea is not correct.

Although many people with "double positive" test had relatively mild symptoms this time, patients with high-risk factors for severe illness may still progress to severe pneumonia.

Judging from the current medical situation, these patients often come to the hospital too late and miss the opportunity for successful intervention. Therefore, we strongly appeal for two points:

1) If people at high risk of severe/critical illness test positive for the new coronavirus, they should take oral drugs to inhibit viral replication as soon as possible to avoid progression to pneumonia or even severe pneumonia, especially the elderly and immunocompromised patients with underlying diseases.

2) For young people without high-risk factors, once they feel cold symptoms, it is recommended that they get a good rest, wear a mask, and undergo COVID-19 antigen testing every day to determine as soon as possible whether they are infected with the new coronavirus.

At the same time, we would like to remind everyone that when conducting the new coronavirus antigen test on your own, you must collect qualified samples in accordance with the requirements of the instructions.

In addition, if you only have respiratory symptoms such as fever, nasal congestion, sore throat, cough, etc., without chest tightness, shortness of breath, palpitations, and normal pulse oxygen, you can rest at home, eat light, nutritious food, and take some Chinese patent medicines appropriately. You don't have to go to the fever clinic. This can reduce the risk of cross infection and the waste of medical resources.

7. NetEase Health: After being cured, is it possible to be infected by other different strains in the short term?

Chen Meifang: Generally speaking, no.

Judging from the current mutation of the new coronavirus, cross immunity exists. Normal people (non-immunocompromised people) will naturally produce protective antibodies after infection, which can last for about 3-6 months. Therefore, generally speaking, it is unlikely that a person who is "healthy" will be infected by other different strains of the new coronavirus within a few weeks.

8. NetEase Health: Is it true that “a person will die if infected with COVID-19 8 times”?

Chen Meifang: Unreliable.

"Infection 8 times" is definitely not a common practice in China, and I have not verified whether it exists abroad. After each infection, the virus should be cleared as soon as possible and attention should be paid to restoring immunity.

Although the saying that "people will die if they are infected with COVID-19 eight times" is unreliable, we should still protect ourselves as much as possible and avoid being infected. Because every time you are infected, your internal organs may be damaged. Some damage may take a long time to repair, which may cause some symptoms to persist for a long time ("getting COVID-19").

9. NetEase Health: Some netizens said that if you have already tested positive for the virus twice, there is no need to get the fourth shot of the COVID-19 vaccine. Is this correct?

Chen Meifang: That’s not true.

According to the interpretation of the National Health Commission's official website "Vaccination Work Plan for Responding to the Recent Novel Coronavirus Infection Epidemic", people at high risk of infection, people over 60 years old, people with more serious underlying diseases and people with low immunity need to complete the second dose of booster vaccination, which is often called the "fourth shot".

As the epidemic continues to change, whether or not to get the COVID-19 vaccine will depend on infection status, previous vaccination history, age, physical condition, etc. It cannot be simply assumed that if you have tested positive twice, you will not be vaccinated.

Finally, I would like to remind everyone to wear masks, wash hands frequently, and ventilate frequently in daily life. Pay attention to the COVID-19 vaccination. In addition, a balanced diet, moderate exercise, adequate sleep and rest, and avoid excessive fatigue can improve one's own resistance and effectively prevent diseases.