As of now, New Coronary Pneumonia has caused more than 3.9 million infections worldwide, with cumulative deaths exceeding 270,000. In the absence of reliable new coronary pneumonia vaccines and specific drugs, the current public health response strategies are broadly divided into two types: remission (social distance, new crown detection, isolation of symptomatic patients) and suppression (including full closure of the large Some non-essential services), both of which reduce the new infections of SARS-CoV-2 by restricting interpersonal contact.
While these measures have a positive effect, they also raise a lot of concerns, which may have a long-term negative impact on economic and social development. On May 7, local time, the international authoritative academic journal Nature Medicine published a study online from Georgia Institute of Technology, Princeton University, McMaster University in Canada, “Modeling shield immunity to reduce COVID -19 epidemic spread “. The research team used the COVID-19 epidemiological dynamic model, based on the SEIR (sensitivity-exposure-infection-rehabilitation) framework, to study the potential impact of the presumed immune rehabilitation patients on the outbreak.
They propose a plan that can have a synergistic effect with the current measures: The new crown rehabilitation person assumes immunity, which It may enable them to return to the general population and safely replace susceptible populations in certain high-touch occupations, which may reduce the overall transmission rate while satisfying the socially necessary operations.
“Our model describes the identification of individuals infected with new coronavirus and recovered through serological testing, which helps reduce further transmission and promotes increased economic activity.” In an article published, Joshua Weitz, a professor at the school’s School of Biological Sciences, said, “We hope that we can consider in advance how to identify individuals who recover and help serve collective interests.” Weitz is the corresponding author and first author of this paper.
Weitz and the plan proposed at the same time are called “shield immunity”. The paper explains that the core of the shield immunity strategy is Using the “interactive replacement” mechanism, by identifying and recovering the SARS-CoV-2 protective antibodies and re-deploying them back to the community. Compared with contact with groups with unknown status, contact with more rehabilitation groups can enlarge the protection Function to build a “shield immunity” among the groups.
The goal of the shield immunity strategy is to help maintain the necessary social interactions, meet social necessities and service functions, and at the same time Reduce the possibility of transmission. The research team believes that the shield immunization method can substantially shorten the duration of the outbreak, reduce the overall burden of the current outbreak, and can have a synergistic effect with the social distance policy. “This method of limiting transmission is Complement current mitigation and suppression measures, while reducing Price. ”
Weitz and colleagues developed and analyzed an epidemiological model. They used serum or antibody tests to identify patients with new coronary pneumonia who have recovered. The model assumes that they have recovered Of patients tested negative for viruses, had protective antibodies against SARS-CoV-2, and were able to safely contact susceptible and infected people.
Scenarios—high propagation rate (R0 = 2.33) and low propagation rate (R0 = 1.57), studied the impact of “shield immunity” on the 10 million model population. The basic infection number R0 refers to the situation where everyone is susceptible Next, a person infected with a certain infectious disease may spread the disease to other people.
The research team evaluates separatelyThe effects of “Medium Shield” and “Enhanced Shield” have been introduced. The former refers to a cured person replacing an additional 2 (α = 2) interactions, and the latter refers to a cured person replacing an additional 20 (α = 20) interactions.
The model results show that the predicted value of the number of deaths is 71000 in the high propagation rate scenario, but the predicted value of the number of deaths is lowered under the medium shield and the reinforced shield. Reached 58000 and 20000. In the low transmission rate scenario, the predicted value of the death toll is 50,000, but under the medium shield and the strengthened shield, the predicted value of the death toll drops to 34000 and 8400, respectively.
The model also shows that shield immunity can be implemented in conjunction with social isolation to reduce healing while reducing interpersonal interactions The person can resume normal life. In practice, shield immunization will not be implemented as a single strategy; instead, multiple interventions will be used in parallel. The combination of social distance and shield immunization can improve the expected hospitalization burden, which shows that shield immunization plays a role in reducing the spread and reducing the negative impact of social distance policies.
The results of the target (age-specific) immunization in this model show that by prioritizing the elderly and protecting high-risk groups, it is possible to further reduce the cumulative deaths by about 30%.
It ’s worth noting that the study reminds the strategy of two important considerations. First, the duration of immunization against SARS-CoV-2 reinfection remains unknown. Previous studies have shown that the duration of antibodies in people who survived from SARS and other related viral infections is about 2 years, and the duration of antibodies in people who survived from MERS infection is about 3 years. Second, determining who has antibodies that may protect them from coronavirus infection on a larger scale will require a certain level of reliable serological testing, which is not yet possible in many countries.
The study therefore emphasizes the need for accurate population-wide serum testing to provide support for public health interventions.
Weit highlights that the determination of serological tests for people with immunity may start with health care workers and they may be more susceptible to the virus. The research team believes that among medical professionals, serological tests Rehabilitation individuals can be identified and they can interact with patients to reduce concerns about infections. Rehabilitation individuals can also help reduce the risk of transmission in nursing homes, food service industries, emergency medical services, grocery stores, retail and other basic businesses. “We want to use serology as an intervention method to find people who are immune to coronavirus, which can greatly reduce the risk of susceptible people. “Weitz said.
Of course, responding to the pandemic will eventually require the development and large-scale production of vaccines. Weitz mentioned that vaccines can increase the immune level of the general population to 60 More than%, but before that, shield immunization may become one of the ways to cope with the challenge. “We have no high tactics. Before developing a vaccine, we must use a variety of strategies to control COVID-19, and shield immunity may be one of them one. “