Source: Frontiers in Life Science

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“Breakthrough”As the name implies, it refers to a pathogen that breaks through the defenses of a vaccine, causing the person who has completed the vaccination to become infected Diseases that vaccines are supposed to prevent. As defined by the U.S. Centers for Disease Control and Prevention (CDC), breakthrough infection with SARS-CoV-2 is defined as a person who is still infected with the new coronavirus more than 14 days after vaccination. At present, most of the COVID-19 vaccines that have been approved around the world still use viral gene sequences based on isolated from Wuhan infected persons in January 2020. Strain sequence. However, with the global pandemic of the new coronavirus, mutant strains are emerging around the world, some of which have been identified to weaken vaccines protective effect. A 2021 study in The Lancet, a top medical journal, showed that when the delta variant was not yet rampant, only 0.2% of the vaccinated population had breakthrough infections. And most of the new crown patients with breakthrough infection are elderly people, or people who are more susceptible to infection due to underlying diseases. April 13, 2022 BioRxiv, a biomedical preprint, published a research article from the University of Texas Medical Branch: SARS-CoV-2 Delta breakthrough infections in vaccinated patients. In this article, the researchers detail antibody neutralization titers in vaccinated patients infected with the Delta variant, and identify the risk of SARS-CoV-2 delta breakthrough infection Neutralizing antibody titer threshold.

Currently, new coronavirus variants including delta strains are challenging vaccine protection efficacy, due to antibody Neutralization is a key factor in vaccine protection, andit is important to determine the level of neutralization in patients with breakthrough infections. This information is critical in guiding vaccine strategy and policy. To determine neutralizing titers (NT50) following infection with the Delta variant in breakthrough patients, the study collected sera from 75 patients who were vaccinated and subsequently infected with breakthrough infection. All patients received 2 doses of Pfizer or Modena vaccine or 1 dose of J&J vaccine. Serum was collected 0-5 days before the positive detection of viral RNA. The researchers measured antibody neutralizing titers (NT50) in 75 sera pairs collected from delta breakthrough patients and performed a series of statistical analyses on these data. The study found that all breakthrough patients had a low NT50 of less than 70. Approximately 76% of patients with breakthrough infection had an NT50 range of <20, 18.7% of patients with breakthrough infection had an NT50 range of 20-50, and 5.3% of patients with breakthrough infection had an NT50 range of 50-69. The above results suggest that:NT50=70 is the neutralization threshold required to prevent breakthrough infection.

Secondly, older people seem to be more susceptible to breakthrough infections. In this study, approximately 58.7% of breakthrough cases were between the ages of 65-97, while those aged 20-40 and 41-64 accounted for all 16% and 25.3% of cases. However, the differences in NT50 between the three age groups were not statistically significant. In addition,Statistics found that almost 90% of breakthrough patients were vaccinated for more than 120 days. However, there was no statistically significant difference in NT50 among breakthrough patients at different time periods after vaccination. However, breakthrough infection does not mean that the vaccine is completely ineffective. Zhang Jun, deputy director of the National Research Center for Infectious Disease Diagnostic Reagents and Vaccine Engineering Technology and deputy dean of the School of Public Health of Xiamen University, said that in research reports with strong data science, various The effectiveness of vaccines in preventing death and severe illness is significantly higher than that in preventing mild illness or infection. Professor Xu Ke, State Key Laboratory of Virology, Wuhan University, introduced, All vaccines are difficult to achieve 100% protective efficacy, span>The lower the protective efficacy of the vaccine, the higher the incidence of breakthrough infection in the vaccinated population. Even with the most protective vaccines, individual differences can lead to breakthrough infections in individuals with lower immune responses. Wang Huaqing, chief expert of China’s disease control and immunization program, said in an interview that The better effect of vaccines is to prevent the occurrence of severe diseases< span>, that is to say, the protection efficiency of the new crown vaccine for severe prevention is higher. He said: It is true that after vaccination, a small number of people fail to protect, which may be due to individual reasons and some other reasons. Original link: https://www.biorxiv.org/content/10.1101/2022.04.12.488092v1Recommended reading< h2>

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