Why is there such a big difference in the severity of positive symptoms before and after the relaxation? An important factor has been overlooked!

Recently, there has been a heated discussion online about the fact that the symptoms of positive cases after the relaxation of the policy far exceeded expectations. Many people even turned their anger towards the relaxation of the policy itself and the experts. They not only questioned that the full relaxation was too hasty, but even denounced the experts for going against science. Academician Zhong Nanshan and Dr. Zhang Wenhong, in particular, were pushed to the forefront and were seriously questioned.

Academician Zhong Nanshan

People are wondering why the vast majority of people had mild symptoms or no symptoms before the relaxation, but most had severe symptoms after the relaxation?

After multiple investigations and analyses, we found that an important factor had been overlooked!

What is going on? Let’s start with the criteria for judging whether a COVID-19 test is positive or negative.

1 What is positive and negative?

In the early prevention and control process, nucleic acid testing played an important role. Once the nucleic acid test result was positive, the person would be isolated and treated. If the nucleic acid test result was negative, he or she would be considered safe and could move freely.

So what is the basis for judging positive and negative here?

After consulting the data, we found that the main thing here is to measure the CT value. The CT value (Cycle Threshold) is also called the "cycle number threshold", which can reflect the amount of virus in the human body.

When doing nucleic acid testing, even for positive people, the virus content obtained by direct sampling is very low. The detection instrument needs to replicate and amplify the virus genes of the sample to a certain extent before it can detect the virus. Each round of amplification will double the number of viruses, that is, 1 becomes 2, 2 becomes 4, 4 becomes 8, 8 becomes 16, and so on. The number of amplifications when repeated amplification reaches a detectable content is the CT value.

The higher the CT value, the greater the magnification required to detect the new coronavirus. The more cycles, the less virus content in the initial sample, the weaker the infectiousness, or even the lack of infectiousness.

On the contrary, the lower the CT value, the more the virus can be detected without too many times of amplification, and the fewer the number of cycles, the higher the virus concentration in the initial sample and the stronger the infectiousness.

So, what is a negative CT value? The answer is: there is no uniform standard among countries and regions.

The standard for Canada is 35, the CT value for Germany is 30, and the CT values ​​for the United States and Japan are 35. In the early stages of the epidemic prevention and control, China's CT value was 40.

After understanding these standards, the doubts of international travelers are solved. Why did the nucleic acid test results in the United States before boarding the plane all turn negative, but immediately turn positive after landing in China? It is because China and the United States have different standards for negative and positive nucleic acid tests.

For example, a CT value of 38 is negative in the United States but positive in China.

It is important to emphasize here that, according to the above standards, people with negative nucleic acid tests do not necessarily not carry the virus, but may carry a relatively low amount of the virus. This also explains why some places have never had a history of positive cases imported, and new cases seem to have emerged out of thin air, making it difficult to trace the source.

2 What changes will the body undergo after being infected with the new coronavirus?

According to relevant information publicly available online, the changes in the human body after infection with the new coronavirus can be roughly divided into the following stages:

Stage 1: Initial stage

During this period, the amount of virus is generally very small. It will enter the cells in the throat of the infected person, use the raw materials in the cells to synthesize its RNA (ribonucleic acid) and protein, assemble into small viruses, and then release them to infect more cells, so the throat will feel uncomfortable at first.

Stage 2: Incubation period

After the virus enters the human body and replicates to a certain number, it will show obvious symptoms. Before the onset of symptoms, it is classified as the incubation period. This incubation period may last from one to several days.

Stage 3: Defense

The number of viruses is already very large, and the immune system sounds the alarm. A large number of macrophages, B cells, and T cells are deployed to fight. At this time, the immune system will also seek resources from the body's temperature regulation center, causing the body temperature to rise, which manifests as a fever.

Stage 4: Stalemate

This is the most severe stage of symptoms. The continuous high temperature consumes too much energy, a large amount of lactic acid accumulates in the muscles, and the symptoms of dizziness, fatigue, and body aches are obvious, so you have to stay in bed to rest. At this time, the battle of immune cells reaches a white-hot state. Macrophages are responsible for engulfing cells invaded by the virus, B cells are responsible for secreting antibodies to neutralize the virus, and T cells will secrete a large amount of cytokines to summon more immune cells to support. The offensive and defensive sides enter a stalemate stage.

Phase 5: Counterattack

Immune cells gradually gain the upper hand, the number of viruses gradually decreases, and the body temperature begins to drop, but the remaining viruses are still "struggling" in the throat, and swallowing saliva will make the throat hurt like "swallowing a razor blade."

Stage 6: Recovery

The immune system achieves a decisive victory, and a large number of dead cells and virus "corpses" accumulate in the nasal cavity and throat, and are cleared out through runny nose, coughing, etc. This stage may last for many days.

Stage 7: Recovery

The nucleic acid or antigen test has shown negative, but the body is still very tired. Some people will relapse after taking a bath or exercising. This is because there may still be a small amount of virus remaining in the body, which is suppressed by the immune system and antibodies, reaching a temporary balance; once the immunity is reduced due to external influences, the virus will come back and attack again.

From the analysis of the above stages, before the relaxation, my country implemented a zero-clearance policy, that is, as long as a positive person was detected, he or she would be isolated and treated. Even if a few virus carriers left out caused infection and transmission, the overall amount of virus in the environment was very low. At this time, the immune system of the infected person had sufficient reaction time to fight, so the symptoms were relatively mild, and a large proportion of them were mild or even asymptomatic.

3 Changes before and after release

Another point that needs to be clarified is that it was very necessary for my country to adopt a resolute zero-COVID policy in the early stages of its fight against the epidemic and persisted in it until the vast majority of citizens had been vaccinated and had produced antibodies.

In the early stages of an outbreak, there were no antibodies in the human body, and the virus could easily break through the immune system's defenses, destroying lung function and causing many deaths. Some countries adopted a herd immunity policy, resulting in the death of millions of people, at an extremely heavy price.

Eliminate viruses

Later, through strict disinfection, wearing masks, frequent hand washing and other measures, the virus content in the environment was reduced to a minimum, "the enemy is weak and we are weak", which delayed the spread of the epidemic, minimized casualties, and bought precious time for the development and injection of vaccines.

After the antibodies are produced, under the strict zero-clearing prevention and control policy, the virus content in the environment is very low, and the human body's defense has been strengthened. "The enemy is weak and we are strong." At this time, some infected people occasionally appear, and a small amount of virus in the human body does not cause a big response. Some are mild symptoms, and many are even asymptomatic. In many places, a group of medical staff have appeared in the square cabin hospital watching the isolated people singing, dancing, and playing with mobile phones. This is the situation before the release. The statistical conclusions of Dr. Zhong and Dr. Zhang Wenhong were made at this stage. In terms of the actual situation at the time, it was indeed the actual performance, so their statistical results were not wrong.

Modular hospital

However, after the lockdown was lifted, disinfection was no longer carried out, the number of positive cases increased rapidly, and the number of viruses entering the environment through various means such as breathing, contact, and aerosol transmission increased greatly. At this time, the number of viruses input by first-time infected people increased greatly, and the immune system was under great pressure from the attack, so the response would be stronger. Many people showed symptoms and even felt quite uncomfortable. This is different from before the lockdown was lifted.

The virus is still the same Omicron, and its toxicity is still the same, but the amount that enters the human body in a short period of time has greatly increased, so the symptoms will be more severe. This is something that not only ordinary people, but also some experts may not have paid enough attention to beforehand.

Nucleic acid testing point

This can also explain another problem, that is, why so many people were infected when they were doing nucleic acid tests before the lockdown was lifted. That is because the nucleic acid testing point is where the virus content accumulates and increases the fastest. In other places, everyone wears a mask and releases very little virus; when nucleic acid sampling, everyone has to take off the mask, and at this time, the positive patients will release some viruses, which will accumulate in the surrounding environment; the more people come, the more viruses accumulate, and the greater the probability that the healthy people behind will be infected.

4 How to deal with the future situation

Now that the virus has been released, a large number of people have been infected, and it is impossible to go back to the lockdown and achieve zero infection. However, there are reports of new strains emerging overseas, and the antibodies produced by previous vaccines may not be effective against the new strains. What should we do?

From the previous analysis, we can know that if we want to defeat the virus, the most critical point is to reduce the virus content as much as possible and maintain the strategic advantage of "the enemy is weak and we are strong".

Therefore, many of the measures taken during the original lockdown are still effective. In places where there are dense crowds and high risks of transmission, we must pay attention to regular disinfection, avoid crowding, wash hands frequently, wear masks when going to crowded places, and frequently wash our mouths and noses with salt water. These measures will help reduce the virus content in the surrounding area and reduce the risk of infection.

In addition, after you recover, you should gradually resume exercise, stay up late less, get enough rest, and have a balanced diet to increase your own resistance. Once you are infected with the virus, it will be easier to fight it and produce effective antibodies again.