A vaccine is a medical immunobiological product containing weakened or completely inactivated pathogens, and in some cases their synthetic analogues. Such drugs contribute to the development of immunity to a specific antigen. The introduction of a vaccine into the body causes an immune response similar to the response to the action of the pathogen itself - antibodies are produced. At the same time, given the weakness of the pathogenic organism, the possibility of getting sick is minimal. Today, medicine uses several types of drugs for vaccination, differing in the mode of action and form of release.
What are the types of vaccines?
In modern immunology for vaccination, several types of agents are used:
- live attenuated - contain a live but weakened strain of the microorganism - the causative agent of the disease;
- inactivated - based on killed (inactivated) viruses and microbes;
- recombinant, subunit, polysaccharide, conjugated - contain only a certain part of the microorganism, for example, its shell, sugar or protein;
- anatoxin - based on toxins produced by the pathogenic microorganism;
- mRNA - use RNA, which "gives" the cells of the human body "instruction" how to produce antibodies to a particular pathogen;
- with a viral vector - contain a neutralized virus used as a "vector" through which the body receives the information necessary to develop self-defense against a specific pathogen.
The most common form of vaccine is injectable solution (shots). Nasal sprays for vaccination are also available. Some drugs are administered by the scarification method, that is, on the skin, while a small scratch is made on the skin, onto which the vaccine is dripped. There is also an oral form of release - the drug is used through the oral cavity, for example, when vaccinated against polio. And if earlier the oral vaccine was only in the form of a solution, now you can increasingly hear about vaccination preparations in the form of tablets. Do they really exist?
Vaccine in tablets: myth or reality?
Until recently, vaccines in tablets were not manufactured. But a few years ago, British scientists at Cardiff University created a non-biological drug that can be taken orally for influenza vaccination. In the scientific world, this event is called a breakthrough.
This drug was based on artificial proteins that mimic the peptides of real viruses. Unlike biological peptides, synthetic ones are not affected by the digestive system. It was this fact that made possible the existence of a vaccine in tablets. The innovative vaccine has already proven its effectiveness. According to data published in the scientific publication The Journal of Clinical Investigation, the use of such a tool causes a powerful immune response. The effectiveness of the drug was confirmed during a test on mice. According to the researchers, a similar result can be expected in the human body. However, scientists acknowledged that so far we are talking only about vaccination against influenza. More time is needed to develop and study vaccines in tablets for other diseases. No less relevant are the experiments of the American biotechnology company Vaxart, Inc in the field of recombinant oral vaccines. The corporation today works in several directions at once, providing for the possibility of vaccination with tablets for noroviruses, seasonal flu, human papillomavirus. Vaxart, Inc.'s vaccine formulations must be enteric-coated to be effective. This coating protects the tablets from the acid in the stomach, allowing them to enter the small intestine, where the immune response occurs to the penetration of the virus into the body. To transport the antigen that generates a protective reaction, the company uses type 5 adenovirus. He delivers it to the epithelial cells. Clinical trials, the second phase of which ended in 2018, proved that the flu vaccine tablet from Vaxart, Inc reduces the manifestations of the disease by 39%. In comparison, the injectable form gives a result of only 27%.
How useful is the discovery of a vaccine in tablets?
Traditional vaccines used in immunology, including oral ones against poliomyelitis, require special storage conditions. In particular, medicines of this group must be stored and transported in refrigerators or freezers, which creates certain difficulties. Tablets do not need a special temperature regime, which greatly simplifies its use. In addition, a means for vaccination in tablet form is also:
- the absence of pain that occurs during injection vaccination;
- reduction in the number of allergic reactions in response to protein in solutions;
- expansion of the age group of vaccinated patients.
COVID-19 vaccine in tablets: is it possible?
With regard to the COVID-19 vaccine, researchers around the world are also actively working to ensure that people can use other forms of immunization not only for intramuscular injections, but also in other forms. There is no publicly available vaccine for COVID-19 yet, but work is already underway in several countries to test an alternative vaccine.
Russian specialists are testing the Sputnik V vaccine in the form of a nasal spray. According to preliminary forecasts, 500 volunteers will take part in testing the effectiveness of the drug in this dosage form. The test is planned to be carried out until December 31, 2023 at the Eco-Safety Research Center (St. Petersburg). In addition, specialists from the Central Research Institute of the Ministry of Defense of the Russian Federation are already working on the creation of a mucosal anti-covid vaccine in the form of marshmallows and chewable tablets.Australian scientists are also working in this direction. The Nucleus Network has begun clinical trials of a nasal spray vaccine against the COVID-19 virus, and Vaxxas, a biotech company, has developed a microneedle patch coated with a COVID-19 vaccine. And as the first tests on rats showed, this method of vaccination is even more effective than the traditional injection - in mice, the immune response began to develop faster. Estonian scientists have also created a spray to prevent coronavirus infection. Ukrainian scientists do not lag behind their colleagues. Last year, the Lviv Institute of Cell Biology of the National Academy of Sciences of Ukraine received a grant to develop a vaccine against COVID-19. To date, the project is almost completed, in Poland, studies are being carried out on laboratory rats. The developers claim to have "created non-infectious virus-like particles without nucleic acid." If the effectiveness is proven, the drug will be widely used, making it in the form of a spray, tablets or medicine. But nevertheless, Israeli scientists turned out to be the most successful in the development of tablet preparations for vaccination against coronavirus. Pharmaceutical company Oramed Pharmaceutical has begun phase 1 testing of an oral vaccine against COVID-19. According to the developers, if the effectiveness of the drug is confirmed, the drug will help to significantly accelerate the pace of vaccination. Another important plus of anti-covid tablets is that they do not require storage at low temperatures, which is mandatory for an injection vaccine.
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- BBC News. – First steps taken for vaccine pills.
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- PR Newswire. – Oramed Announces Oravax’s Oral COVID-19 Vaccine Has Received South African Approval to Initiate Phase 1 Trial.