Why do a large number of asymptomatic infections continue to appear in the current round of the epid

Because the transmission speed of the virus is really very large, the infectivity is also very large, and the source has not been found in the first time every time, and the source has not been cut off, so the epidemic has been spreading, and a large number of asymptomatic infections have been appearing.

Because asymptomatic infections spread very quickly, asymptomatic infections cannot be detected at the first time, so a lot of people are transmitted.

Because the current round of the epidemic in China is related to the Omicron variant, this variant is particularly contagious.

The first is the etiological characteristics. The new coronavirus in the current round of epidemic in Shanghai is classified into Omicron variant subtypes, which are characterized by strong insidiousness, fast transmission speed, short incubation period, and atypical clinical symptoms, and the main epidemic strain in the country is the Omicron variant. Recently, the press conference of the joint prevention and control mechanism also introduced that the proportion of mild and asymptomatic infections in hospitals in the country is more than 95%.

The second is about the age characteristics of the infected population. The average age of the infected people in this round of the epidemic is 40 years old, and the proportion of people under the age of 60 is accounted for. Correspondingly, the proportion of asymptomatic people is also higher.

Third, it is related to mass vaccination. At present, the total number of new crown vaccinations in Shanghai has exceeded 55 million, more than 22 million people have completed the full course of vaccination, and more than 11 million people have completed booster vaccination. The vast majority of people infected in this round of the epidemic have been fully vaccinated, the population immunity is increasing, and the proportion of asymptomatic infections will also increase.

Fourth, it has to do with the way the infected person is found. Symptomatic infected people are often found at sentinel surveillance sites in hospital fever clinics or pharmacies during symptomatic presentations. Asymptomatic infections are mainly found through nucleic acid testing and population screening.

Recently, we have carried out regional grid nucleic acid screening and found a certain number of positive infections, including asymptomatic infections in the latent period and early stage.

First, the Omicron variant has a very important related feature: the proportion of asymptomatic infections is relatively high, and the current round of epidemic in Shanghai has fully demonstrated this characteristic. There are many reasons for the high rate, such as widespread vaccination, and the formation of effective resistance even after infection.

After being infected with the virus, the patient's condition can be mild, or even asymptomatic, which is an effect of epidemic prevention.

We've been fighting the Omicron variant for a while, and it's coming too fast. There is a deep feeling that we can't outrun the delta, alpha, and beta variants with the same way we used to play them. It is necessary to run at a faster speed, and this faster speed means that the implementation of measures must be fast, and the speed must be fast.

COVID is unlike any other infectious disease we know before. The presence of a large number of asymptomatic infections has greatly changed the development trend of the epidemic. In the past, China's new crown prevention and control has been dominated by "external prevention of importation, internal prevention of **", but this round of epidemic has shown a significant localization trend, and the epidemic prevention and control strategy should be adjusted and optimized according to these new situations and characteristics.

Taking the current round of epidemic in Shanghai as an example, the proportion of asymptomatic infections has reached more than 90%. In this regard, Xu Jianguo told the first financial reporter: "The control of asymptomatic infections is the 'Achilles heel' of the new crown epidemic.

That is, one of the biggest weaknesses of the new crown epidemic. We must pay attention to asymptomatic infections, and to control the epidemic, we must first control asymptomatic infections, control the spread of the virus, and control the spread of the epidemic. At the same time, it is necessary to control severe disease and reduce death.

Asymptomatic infections do not show any symptoms in the early stages of infection, which also leads to contact with healthy people, and once they are exposed, they can spread the virus again.

In the past few days, there have been many imports from abroad.

Changes in the characteristics of variants.

Recently, there has been a rapid increase in new cases in some neighboring countries and regions, and local epidemics in China have been sporadic in many places. As the largest domestic city receiving overseas flights, Shanghai has continued to increase the pressure of overseas epidemic imports in recent days.

The local virus strain in this round of epidemic is the Omicron variant. Professor Hu Bijie explained that the pathogen of this variant has its own changes, and in general, the proportion of infected patients with lower respiratory tract infection has decreased significantly, the proportion of fever has decreased, and some infected patients have no headache and brain fever symptoms, and the pathogenicity rate has also decreased.

Due to the characteristics of the Omicron variant, many infected people are "asymptomatic". The so-called asymptomatic infected person is already infected with the new coronavirus, and the nucleic acid test of the new coronavirus is positive, but there are no related symptoms, and there are no characteristic changes in lung imaging.

In addition to the causes of variants, large-scale population immunization and enhanced immunity of the population will also increase the proportion of asymptomatic infections.

After vaccination, an "immunity wall" is built in the population, and the resistance of the population increases, which means that the virus in the body will not multiply in large numbers, once the virus concentration increases, the vaccine takes effect, and the antibody responds to fight back, although the viral load will be detected (positive), but the virulence is difficult to exert (no symptoms).

It is not counted as a local epidemic.

The difference between local cases and asymptomatic infections.

The difference between local cases and asymptomatic infections belongs to the new coronavirus infected group, but there will be some differences in the clinical symptoms and treatment methods of the two.

For local cases, the nucleic acid test is positive, and there are obvious symptoms of new coronavirus infection, such as fever, cough or dry cough, sore throat, etc., local cases can be divided into four types according to the severity: mild, ordinary, severe, and critical; Although the asymptomatic infected person is positive in nucleic acid testing, he does not appear or does not find that he has symptoms such as fever, cough, sore throat, fatigue, etc., and no imaging changes are found after CT examination.

Secondly, for local cases, they need to be isolated and carried out in designated hospitals or designated places, mainly general and drugs; Asymptomatic infected people generally do not need to receive special**, because there is no specific drug for the new coronavirus, and it needs to be carried out according to the symptoms**, and the main isolation is medical observation.

2 Why are asymptomatic infections not considered confirmed?

The reason why asymptomatic infections are not counted as confirmed cases is mainly because asymptomatic infections do not have typical symptoms of the new coronavirus such as fever and cough, and they are not included in the confirmed cases, mainly based on three considerations:

1. Asymptomatic infections include two groups of people, the first part is the so-called hidden ** infected people, who have no symptoms from beginning to end after being infected with the new coronavirus, or the symptoms are very mild; The other part of the population is still in the incubation period after infection, and symptoms may come out later, but there may be no symptoms at the time of testing, which belongs to the incubation period. From the perspective of management, "asymptomatic infections" are used to refer to these people.

2. For the monitored asymptomatic infections, the Health Commission will specifically report the number of asymptomatic infections and how many asymptomatic infections have become confirmed cases in the daily epidemic data report. The information is public, complete, and not missing.

3. For asymptomatic infections, the Health Commission will carry out strict medical isolation and observation measures, and has been closely monitoring their health conditions.

3 Asymptomatic infected people are not fine.

No. Although asymptomatic infected people do not have typical symptoms of new coronavirus infection, they are also infectious to a certain extent, and they still need to be isolated, observed, and tested for signs in accordance with the requirements of confirmed cases.

For asymptomatic infected people, their travel and normal life will be restricted to a certain extent, so if they are defined as asymptomatic infected people in their lives, they need to inform their communities in time, and contact designated hospitals with the help of staff to actively cooperate with further treatment measures.

Asymptomatic infections are infectious, and they must be regarded as local epidemics, and the usual official website reports include asymptomatic infections in local epidemics.

Asymptomatic infection is counted, and local epidemics generally refer to asymptomatic infections or confirmed cases of new crown in the local area, which can be regarded as a sign of local epidemics. Anyone who has the basic signs of the new coronavirus, such as officially confirmed cases or asymptomatic infections, will be defined by ** and other relevant departments as having a local epidemic situation, which will be used as the root cause of the prevention of the source of the epidemic.

Counting the local epidemic, it means that they have carried the new coronavirus, but they have not yet shown the obvious symptoms of the virus, and they belong to the asymptomatic infections among the confirmed cases.

Asymptomatic infections should not be counted as local outbreaks, as asymptomatic infections may be infected with viruses from other transmission sources.

The local outbreak includes reported confirmed and asymptomatic cases; If an inbound person is infected before entering the country or during the flight, and the onset of the disease after entering the country is an imported case. If the onset of the disease during the closed-loop management period after entry causes infection among local people with no history of overseas infection, causing social transmission, it is a local epidemic related to overseas.

Asymptomatic infections are not confirmed cases and therefore are not counted as new infections.

There are four main reasons involved:

First, the serious epidemic situation abroad has led to an increase in imported cases.

Since last year, the end of 2021, the fourth round of the global epidemic peaked, and the cases imported from abroad every day, as well as the related viruses that came in with foreign trade goods, were even more difficult to prevent. In particular, some high-incidence countries are unimpressed with the new coronavirus, downplaying the severity of the epidemic abroad. There are even rumors that a certain country still goes to school normally after getting the new crown pneumonia, and treats the new crown pneumonia as a normal flu.

It can be said that the pressure of the recent epidemic import has increased significantly compared with 2021 and 2020.

Second, Omicron is highly transmissible.

The recent global outbreak of new crown pneumonia is mainly Omicron, which is particularly transmissible, and once a case is found, it has often spread to a certain extent, and the controllability is not high.

Third, there is a lot of mobility during the Spring Festival.

The end of 2021 happens to be the traditional Chinese festival Spring Festival, and China has always taken the New Year's reunion as a major feature of the festival. In addition, in some rural areas, the management is relatively lax, and villagers never wear masks when they go out, and there are various gathering activities during the Spring Festival.

Fourth, Omicron has mild symptoms, and some people do not pay attention to it.

Due to the mild symptoms of Omicron, some people think that it is similar to the flu and do not pay attention to it, and the prevention and control requirements have also been relaxed.

In any case, epidemic prevention and control and fighting the epidemic are the top priorities at present, and it is the responsibility of every Chinese citizen to actively cooperate with the country and actively do a good job in protection.

There are four main reasons for this:

First, since December 2021, the global new crown pneumonia has entered the peak of the fourth wave of the epidemic, and it has now been 11 consecutive weeks, and the number of cases reported every week has exceeded 10 million, and it is still at a high epidemic level. Especially since the beginning of this year, the epidemic situation in our neighboring countries and regions has risen rapidly, and the "pressure difference" between the epidemic level and my country has been increasing. From January to February this year, the number of infected people imported per day averaged 91 per day, much higher than the 22 cases in 2020 and the 32 cases in 2021.

Since March this year, the average number of imported infections per day has exceeded 200, and the maximum number of cases in a single day can exceed 300. It can be said that the pressure on the import of the epidemic has increased significantly recently.

Second, the Omicron variant, especially the sub-branches, which have been circulating in the world recently, are more transmissible and insidious than previous virus strains, and it is indeed more difficult to detect them early, resulting in the epidemic often affecting a certain range when it is discovered, and it can be said that it is more difficult to deal with and control the epidemic.

Third, the end of February this year coincided with the end of China's Spring Festival holiday, the start of the spring semester of students, the resumption of work of enterprise workers, etc., which brought about a large-scale flow of personnel, coupled with the increase in various personnel gathering activities such as conference training, weddings and funerals, etc., which can be said to have become the "spreader" and "amplifier" of the epidemic, resulting in the rapid spread of the epidemic, and even cross-regional transmission.

Fourth, some places believe that the Omicron variant has mild symptoms, flu-like, lax and paralyzed thinking, and has a mentality of "resting and slowing down", and is not well prepared in all aspects, and the requirements for normalized prevention and control and emergency response have been relaxed.

It is brought about by the entry and exit of people from outside the country.

In this round of the epidemic, there are no symptoms and most infected people, but this does not mean that the virus is "weaker", and the virus variants are less pathogenic, but more transmissible. Therefore, everyone should not easily relax their vigilance, the Omicron variant is more transmissible and mainly invades the upper respiratory tract. According to relevant studies, the virus spreads 77% faster than the previous Delta strain.

First, it does not mean that the virus has weakened.

The coronavirus has been around for a very long time, and the virus is constantly mutating. The first mutation became the Delta strain, then the Omicron strain, and then the Omicron subvariant, and maybe it will continue to mutate in the future, so what you can do now is to take protective measures. Although these strains have become less pathogenic, most patients are asymptomatic infections.

However, the speed of transmission is also relatively faster, and if an asymptomatic infected person has traveled to a place, the people around him may be infected. Therefore, no one should let their guard down, and if the virus invades the lungs, it may still cause the asymptomatic infected person to become sicker. <>

Second, everyone should get vaccinated in time.

In fact, there are more and more asymptomatic infections, not only because the pathogenicity of the strain has become weaker, but also because everyone has been vaccinated in time, and the body's immunity has been enhanced. Nucleic acid testing can effectively detect everyone's physical condition, and the sooner it is discovered, the symptoms will not be particularly serious, and it can be ** faster. <>

III. Concluding remarks.

Although everyone's immunity is increasing, everyone should pay attention to prevention in the face of these more insidious and fast-spreading strains. No matter which area residents go out, they must wear masks and disinfect them in time. Don't hang out with friends too often, and don't always join in the fun.