Beijing will conduct a population serum antibody survey, experts explain in detail

Recently, Wang Quanyi, deputy director of the Beijing Center for Disease Control and Prevention, said in an interview with the media that Beijing has established temporary population immunity and the risk of a new coronavirus epidemic in the near future is relatively low. In order to comprehensively assess the new coronavirus infection situation and understand the serum antibody levels of the community population, Beijing is about to conduct a population serum antibody survey.

What is a serum antibody survey?

According to Wang Quanyi, the Beijing population serum antibody level survey is planned to be completed from February to March this year. The survey adopts a multi-stage stratified random sampling survey method, selecting about 5,000 community people from 16 districts and economic development zones for questionnaire surveys and serological specimen collection.

He said that the research will provide a reference for optimizing resource allocation and COVID-19 prevention and control in the future.

As early as 2020, the Chinese Center for Disease Control and Prevention organized and completed a nationwide COVID-19 serological epidemiological survey and analysis. The survey covered three types of regions, including Wuhan, cities and prefectures outside Wuhan, Hubei, and six provinces outside Hubei (Beijing, Liaoning, Shanghai, Jiangsu, Guangdong and Sichuan). A sampling survey design was used to select more than 34,000 people in the community, and the level of COVID-19 infection in the population was estimated by testing the serum COVID-19 antibodies of the survey subjects.

Data map. Photo by Yuan Sui

In the "Scientific Understanding of the Prevalence of Coronavirus Antibodies in the Population - Questions and Answers on the Results of the National COVID-19 Serological Epidemiological Survey" released by the Chinese Center for Disease Control and Prevention in 2020, it was explained that a serological epidemiological survey is an epidemiological survey conducted using serological methods and techniques. By analyzing and studying the distribution patterns of specific antigens or antibodies in the serum of the population and their influencing factors, it clarifies the occurrence and spread of infectious diseases and evaluates the effectiveness of vaccination.

Why is it necessary to conduct a serum antibody survey?

Wang Yimin, a doctor in the Department of Respiratory and Critical Care Medicine at the China-Japan Friendship Hospital, told Chinanews.com that the new coronavirus serum antibody test includes specific IgM antibodies and IgG antibodies. The positive rate is low within one week of onset. The IgG antibody titer in the recovery period is more than 4 times higher than that in the acute period, which can be used as a basis for retrospective diagnosis of new coronavirus infection.

Wang Yimin also said that antibody testing may have false positives, such as in vaccine recipients, patients with previous immune diseases such as rheumatoid arthritis, etc. Therefore, serological antibodies are generally not used alone as the basis for diagnosis in clinical practice. A comprehensive judgment must still be made in combination with clinical manifestations, epidemiological history, and antigen or nucleic acid testing.

Wang Yimin pointed out that the serum IgG and IgM antibodies currently monitored are not completely equivalent to the protective neutralizing antibodies after infection with the new coronavirus. Therefore, it cannot be assumed that the high antibody titer is related to "protection". Institutions with conditions can carry out neutralizing antibody testing. The level of this indicator has a certain role in guiding vaccination, judging the overall immune protection level and the risk of repeated infection.

Regarding the population serum antibody survey conducted in Beijing, Wang Quanyi also said that considering that the antibody level will naturally decrease over time, dynamic assessments may be carried out in the future as needed.

Source: China News Network, Red Star News