Asymptomatic infection

  With the continuous development of the new crown pneumonia epidemic around the world, more and more "asymptomatic infections" have entered the public's sight and life, and become the focus of everyone's attention.

In the new crown pneumonia epidemic in Hebei this time, a large number of asymptomatic infections were also found.

So what is an asymptomatic infection? Are asymptomatic infections contagious?

How can we prevent possible transmission from asymptomatic infections?


What is an asymptomatic infection?


  The "New Coronavirus Pneumonia Prevention and Control Plan" (Seventh Edition) issued by the National Health Commission clearly states:

asymptomatic infection refers to the respiratory tract and other specimens that have tested positive for the pathogen of the new coronavirus and have no relevant clinical manifestations, such as fever and dry cough. Those with self-perceived or clinically recognizable symptoms and signs such as sore throat, and CT imaging without imaging features of new coronary pneumonia.

  There are two situations for asymptomatic infections: one is that they have no self-perceived or clinically recognizable symptoms and signs after 14 days of quarantine medical observation; the other is the incubation period of "asymptomatic infection".

That is to say, an

asymptomatic infected person may always be asymptomatic and is a virus carrier; or over time, relevant clinical symptoms may appear and become a confirmed case.


Are asymptomatic infections contagious?


  Based on the current epidemiological investigations and research results, the incubation period of the new coronavirus in the human body is 1-14 days, mostly 3-7 days; the infection is relatively strong 1-2 days before the onset and the initial stage of the onset.

It can be seen that

asymptomatic infections are contagious, especially those with asymptomatic infections in the "incubation period" are relatively contagious in the 1-2 days before and at the beginning of the onset.

Some asymptomatic patients only sampled and tested positive for the new coronavirus nucleic acid, or positive for the new coronavirus-specific IgM antibody or IgG antibody. They have never had any relevant clinical symptoms and have no disease. Compared with severely ill patients, their excreted virus transmission ability Much weaker.


How are asymptomatic infections found?


  Asymptomatic infections are mainly found through the following four channels:


Close contacts of new coronary pneumonia cases

, some of these people were found during the medical observation period;


Some asymptomatic infections were found

during the active detection process in the cluster epidemic investigation



In the process of tracing the source of infection of new coronary pneumonia cases,

asymptomatic infections may be found

during active testing of exposed populations



When proactively testing people with cases of new coronary pneumonia, travel history and residence history in areas that continue to spread

, asymptomatic infections may be found.


How to prevent infection from asymptomatic infection?


  As asymptomatic infected people do not have any obvious symptoms and signs, they rarely go to medical institutions for treatment. They are concealed in the population, difficult to be found, and there is a risk of transmission.

  During the new crown pneumonia epidemic, relatives, neighbors, acquaintances, friends, and colleagues may have asymptomatic infections.

Therefore, to prevent infection from asymptomatic infections, the most basic way for the general public is still:

(1) Carefully protect yourself.

Wear masks, wash your hands frequently, and ventilate frequently. Public items and some personal items that individuals often use (such as door handles, telephones, mobile phones, etc.) are regularly cleaned and disinfected.

(2) Go out less and don't gather together.

Do not go to high-risk areas, and do not have close contact with people from high-risk areas, high-risk occupations and other unclear health conditions; do not gather, do not gather, do not visit relatives or friends, do not get together or gather, and keep socializing with others more than 1 meter distance.

(3) Pay attention to civilized etiquette.

Cough and sneeze over your mouth and nose.

Advocate split meal system, use public chopsticks and spoons.

(4) Strengthen health monitoring.

Pay close attention to the health of yourself and your family members. Once you have suspicious symptoms, go to a nearby regular hospital for medical treatment as soon as possible, and strive for early detection, early diagnosis, early isolation, and early treatment.

(5) Develop a good lifestyle.

Reasonable diet, regular work and rest, scientific exercise, adequate drinking water, and continuously improve body immunity.

Those who have the conditions should be actively vaccinated against influenza and new crown.

About Home

  The number of confirmed cases of new coronary pneumonia in Hebei Province is still increasing. In order to strengthen the prevention and control of the epidemic, Shijiazhuang, Xingtai and Langfang have implemented closed management of the whole area, and many residents have been living at home for many days.

Many people have doubts about what can and cannot be done during the closed management period.


Will singing in the community spread the virus?


  Someone asked, during the closed management period, will the behavior of community residents collectively opening windows and singing songs spread the virus?

  It is currently believed that the spread of respiratory droplets and close contact is the main route of transmission of new coronary pneumonia.

Contact with virus-contaminated items can also cause infection.

When exposed to high concentrations of aerosols for a long time in a relatively closed environment, the virus may spread through aerosols.

  Xu Shuchang, chair professor of the Department of Respiratory System at the Chinese University of Hong Kong, once said that under normal circumstances, an interval of 1 to 1.8 meters is still a safe distance for respiratory droplets to spread.

Feng Luzhao, a researcher at the Infectious Diseases Division of the Chinese Center for Disease Control and Prevention, once said: The spread of droplets is very short, usually within 1-2 meters, and the virus will not float in the air for a long time.

  Most of the residents who organize singing live in buildings. The windows are open when singing, and the distance between the buildings has exceeded two meters.

Feng Zijian, deputy director of the China Centers for Disease Control and Prevention, once said: Whether singing in a community organization is contagious depends on the distance, and there is no problem with opening the windows between the buildings to sing.

  Therefore, under the premise of ensuring a safe distance, residents can sing at home, which is also a good way to improve mood, ease emotions, and reduce stress.


Can windows be opened for ventilation during the epidemic?


  Droplets with pathogens can cause infection, but the scope of droplet transmission is limited. In most cases, the infection of new coronary pneumonia occurs in close contact with the patient. If you maintain a certain contact distance, you can reduce the risk of infection. .

  In addition, the new coronavirus has separated from its host and will not survive for long outdoors and will lose its activity quickly in the outdoors with good air circulation.

Therefore, there is generally no new coronavirus in the air.

Even if the outdoor air contains viruses, because the air is constantly flowing, the density will be very, very low, the possibility of entering the room is very small, and the possibility of infecting indoor people is even smaller.

  The purpose of opening windows for ventilation is to enhance indoor and outdoor air circulation. If people stay in a relatively confined space, the exhaust gas exhaled by people will accumulate more and more indoors, and the oxygen in the air will gradually decrease, which is not good for health. Opening windows for ventilation can keep the indoor air fresh, and fresh air is beneficial to everyone’s immunity, thereby reducing the risk of virus infection.

  It is recommended to open more windows for ventilation in sunny weather and suitable outdoor temperature conditions to increase indoor air circulation, 2-3 times a day, 20-30 minutes each time. When opening windows for ventilation, keep warm and prevent colds.


Can the fresh air system be used during closed management?


  The main function of turning on the fresh air system is to enhance the circulation of indoor and outdoor air.

If there are no infected patients in ordinary families, the fresh air system can be used.

However, if there are people who need to be isolated at home, natural ventilation should be used as the mainstay in the isolation room, supplemented by disinfection.

The air conditioner in the room is not necessary. If it is used, it needs to be disinfected in advance, and ensure that the air conditioner in each room is ventilated independently and does not circulate.

The air conditioner must be disinfected before use.

  During the epidemic, the use of centralized air conditioning and ventilation systems can be implemented according to the following principles: crowded places should suspend the use of centralized air conditioning and ventilation systems; non-public places that need to continue to use centralized air conditioning and ventilation systems should be cleaned and disinfected regularly ; Other places that need to continue to use centralized air conditioning and ventilation systems should be operated with fresh air.

Before starting or shutting down the cold and heat source equipment, let the fresh air blower and exhaust air blower run one or two more times for ventilation.

Regularly clean, disinfect or replace parts of the centralized air conditioning and ventilation system.