How will coronavirus vaccines work?

In an unprecedented race to find a definitive solution to the pandemic, more than 180 candidate coronavirus vaccines are currently being developed around the world, and at least 42 of them are already being tested in humans. All of these vaccines stimulate the immune system to attack. in SARS-CoV-2 coronavirus proteins, such as the surface pin that allows the virus to enter the cells. However, the candidate vaccines are divided into sub-categories according to the production process and their active ingredients. , Ioannis Danasis, Maria Gavriatopoulou and Thanos Dimopoulos) summarize the developments according to a review published in Nature by Florian Kramer, professor of microbiology at Mount Sinai Medical School in New York. Inactivated vaccines Because the whole virus enters the body, antibodies are produced not only against the virus binding protein, but also against its envelope. Three such vaccines are in Phase 3 studies in China, while one from India, one from Kazakhstan and two from China are in Phases 1 or 2 of clinical trials. Live attenuated vaccines. These vaccines are produced from an attenuated form of the virus, the which multiplies to some degree without causing disease, but eliciting an immune response commensurate with the natural infection. Inactivation is achieved either by exposing the virus to specific conditions (such as low temperatures, or growing in non-human cells), or by genetically modifying the virus (eg by removing genes responsible for the immune response). The great advantage of these vaccines is that they also induce an immune response in the mucosa. They can also be given through the nose, protecting the upper respiratory tract which is the main source of virus entry. However, the disadvantages of these vaccines are questionable safety and difficulty in production. Only three vaccines in this class are in the preclinical phase. Recombinant Protein Vaccines These vaccines contain various viral proteins such as surface protein, RBD protein and virus-like protein particles (VLPA-like virus particle). It is made in proteins, and the subsequent immune response is affected. These vaccines have the advantage that they do not need a live virus to be produced. However, the production of the protein spike of the virus is difficult. RBD protein is easier to produce, however because it is a small protein it is considered more prone to developing virus resistance compared to whole spike vaccines. Many of these vaccines are in the preclinical stage or in Phase 1. Non-replicable vectors. These vaccines are based on a different virus, which has been created to produce the superficial spike of the virus, but cannot be multiplied by the removal of certain genes. Adenoviruses are usually used as vectors. These vaccines induce both B and T cellular immunity and are administered intramuscularly, however any pre-existing immunity to the adenovirus vector may make the vaccine less effective. In this category there are vaccines in Phases 1 to 3. Copying vectors In this case vectors that produce a recombinant gene are used, in this case the spike protein. Because the vector multiplies as a point in the host, these vaccines elicit a greater immune response, and some can be given to the mucosa, thus inducing mucosal immunity (especially those based on the Newcastle virus). Currently, two vaccines in this class are in phase 1 studies. Inactivated carriers of the virus In pre-clinical stages, there are vaccines based on inactivated virus carriers, which produce the coronavirus tip and then inactivate it. These vaccines are safer because the virus cannot multiply in immunocompromised patients either. DVA Vaccines This approach utilizes “plasmids,” cyclic DNA molecules derived from bacteria. Typically, these plasmids contain a gene that encodes the virus spike protein, which is produced in the vaccinated person after injection. However, although these vaccines can be produced in large quantities and relatively easily, they induce low immunogenicity and often need to be administered by specialized methods, limiting their use. Four vaccines are in Phase 1/2 studies. RNA vaccines These vaccines use either mRNA (messenger mRNA) or self-replicating RNA, which is usually given by lipo-nanoparticles (LNPs). Vaccines of these categories are being tested in Phase 1-3 studies. Although they have the advantage of entirely in vitro production, the potential problems of large-scale production remain unknown as it is a new technology. Follow it on Google News and be the first to know all the news. See all the latest news from Greece and the world, at

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