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Can asymptomatic patients be infected? Experts interpret asymptomatic patients

Can asymptomatic patients be infected? Experts interpret asymptomatic patients

1. What is New Coronavirus asymptomatic infection?

Asymptomatic COVID-19 infected persons (hereinafter referred to as asymptomatic infections) refer to symptoms and signs that can be self perceived or clinically recognizable without relevant clinical symptoms, such as fever, cough and sore throat. But respiratory tract specimens are positive for COVID-19 etiological tests. Asymptomatic infection can be divided into two situations: first, the infected person has positive nucleic acid test. After 14 days of incubation period, there are no symptoms and signs that can be perceived or clinically recognized, and he is always asymptomatic infection; Second, the infected person's nucleic acid test is positive, and there are no self perceived or clinically recognizable symptoms and signs at the time of sampling, but then there is a certain clinical manifestation, that is, the state of 'asymptomatic infection' in the incubation period.

Two, China's prevention and control requirements for asymptomatic New Coronavirus infections

In January 28th, the national health and Health Committee issued the COVID-19 infection prevention and control plan (Third Edition), which included the asymptomatic infection of New Coronavirus in the prevention and control management. In the subsequent revision process, it made clear requirements for the reporting and management of asymptomatic infected persons. If asymptomatic infection is found by various medical and health institutions at all levels, it shall be reported directly through the Internet within 2 hours. After receiving the report of asymptomatic infected persons, the county (District) level disease control institutions shall complete the case investigation within 24 hours, register the close contacts in time, and timely report the case questionnaire or investigation report through the infectious disease report management information system. Asymptomatic infected persons shall be isolated for 14 days. In principle, those who have been isolated for 14 days and have negative nucleic acid detection of two consecutive samples (the sampling time shall be at least 24 hours apart) can be released from isolation; If the nucleic acid test is still positive, continue isolation medical observation. If any clinical manifestation occurs during isolation medical observation, it shall be transferred to confirmed case in time for standardized treatment. Asymptomatic infected persons and close contacts should also be subject to 14 days of centralized isolation medical observation.

3、 How can asymptomatic infections be found? So far, how many asymptomatic infections have been found in China?

At present, we mainly detect asymptomatic infections through the following ways: first, carry out active detection during the medical observation period for the close contacts of New Coronavirus pneumonia cases. The second is the active detection in the investigation of aggregated epidemic situation; Three, we should actively detect the exposed population in the tracing process of infectious source of New Coronavirus pneumonia. The four is to carry out active detection of travel history and residence history in some areas where New Coronavirus pneumonia cases continue to spread.

As of 24:00 on March 30, 2020, 1541 asymptomatic infections have been observed, including 205 imported from abroad.

4、 Are asymptomatic infections contagious?

According to the monitoring data of close contacts carried out by the state and some provinces, there are second-generation cases of close contacts of asymptomatic infected persons. In the epidemiological investigation, it is found that individual aggregated epidemic situations caused by asymptomatic infected persons. Studies with a small sample size show that the viral load in the respiratory samples of asymptomatic infected persons is not much different from the confirmed cases. Based on the current monitoring and research, asymptomatic infected people are infectious, but the length of infection period, infectious strength and mode of transmission still need further scientific research. Some experts believe that in view of the fact that pathogenic nucleic acids can be detected in the respiratory tract specimens of asymptomatic infected persons, but due to the absence of clinical symptoms such as cough and sneezing, the chance of transmission caused by pathogen excretion is relatively less than that of confirmed cases.

5、 Risk assessment and prevention of asymptomatic infection

Asymptomatic infections are at risk of transmission. One is the concealment of communication. Because asymptomatic infected people have no obvious symptoms and signs, it is difficult to be found in the population, and the transmission caused by it is also difficult to prevent. The second is the subjectivity of symptoms. Those with mild or atypical symptoms may feel that they are not infected with COVID-19 and do not take the initiative to visit a medical institution. The third is the limitations of the discovery. Due to the detection window period, it is difficult to find all asymptomatic infections by nucleic acid detection and serological detection. The existing asymptomatic infections are mainly found through active screening of close contacts of cases, investigation of infection sources, investigation of aggregated epidemic situation and active detection of personnel in high-risk areas, and some asymptomatic infections are difficult to be found.

Therefore, we should highlight the monitoring of asymptomatic infected persons, strengthen targeted screening, and expand the detection scope to close contacts, key areas and key populations of discovered cases and asymptomatic infected persons. Once asymptomatic infection is found, it is necessary to strictly focus on isolation and medical observation according to the requirements of "four mornings", and isolate medical observation should also be carried out for close contacts.

Because some asymptomatic infected persons are always asymptomatic, it is impossible to find and isolate asymptomatic infected persons as the leading measure in the actual prevention and control work. Therefore, we will continue to focus on timely detection, isolation and diagnosis of patients, and do a good job in close contact management. China's experience shows that timely detection and isolation of confirmed cases and appropriate measures to reduce interpersonal contact can basically block the spread of the epidemic.

6、 How to do a good job in the prevention and control management of asymptomatic infected persons in the next step?

First, improve the prevention and control plan. Pay close attention to sampling a certain proportion of samples in key epidemic areas, carry out investigation and epidemiological analysis and Research on asymptomatic infected persons, improve prevention and control measures, revise and improve prevention and control plans and diagnosis and treatment plans, scientifically deal with the infection risk caused by asymptomatic infected persons, and curb the possible spread of new epidemic situations.

Second, increase screening and monitoring. Targeted screening efforts will be strengthened, and the detection scope will be expanded to close contacts, key areas and key populations of discovered cases and asymptomatic infections. Combined with the actual situation of returning to work, production and school, strengthen the monitoring of key cities, key populations and key places to find hidden dangers to the greatest extent. Take precautions against cross-border import and export of epidemic situations, and conduct nucleic acid testing for all inbound personnel. After finding asymptomatic infected persons, carry out epidemiological investigation in time, find out the source, and publish information openly and transparently.

Third, strengthen management and treatment. Once asymptomatic infected persons are found, they shall be strictly isolated and medically managed according to the requirements of "four morning", and close contacts shall also be subject to isolation medical observation. If symptoms occur during isolation, they shall be immediately transferred to designated medical institutions for treatment.

Fourth, strengthen group prevention and control. Adhere to the combination of groups and professionals, strengthen the popularization of epidemic prevention knowledge, guide the public in scientific protection, widely carry out training, and improve the prevention and control ability and level of grass-roots disease control personnel, medical personnel and community workers. From April 1, the report, prognosis and management of asymptomatic infected persons will be published in the epidemic notification to respond to social concerns in a timely manner.

7、 How to do personal protection?

The serving of individual dishes should be strengthened. The public should strengthen their awareness of self protection and health and civilization, strengthen environmental hygiene and personal hygiene protection, and develop healthy lifestyle behaviors such as washing hands frequently, wearing masks, paying attention to hand hygiene, one meter line, ventilation, cleaning and disinfection, dining separately, reducing the number of places to gather and scientific wearing masks when sick. We should widely carry out patriotic health campaigns, spread health knowledge to every family and individual, form good health habits and civilized, healthy, green and environmental friendly lifestyles, and improve the level of mental health and health literacy. If an individual has a positive nucleic acid test, there is no need to panic. He should actively cooperate with the medical and health institutions to do a good job in health monitoring and isolation medical observation, report in time after fever, cough and other symptoms, and accept the standardized diagnosis and treatment of the medical institutions.