Vaccination

In order to protect our lives, families, loved ones, in order to live in infectious safety, it is necessary to understand what vaccinations are, what are their advantages and disadvantages.

Vaccination is the introduction into the body of substances that are recognized by the immune system as the causative agent of an infectious disease, as a result of which an immune response develops, consisting in the production of antibodies that neutralize the pathogen in case of repeated exposure to the body.

Why is vaccination necessary?

Each of us has the right to make decisions about our health and the health of our children. The question of the need to administer the vaccine to yourself or your child according to the vaccination schedule or before traveling to exotic countries each time becomes the subject of lengthy discussions in the family. But can vaccination still remain a personal matter for everyone, if coverage of the vaccinated population must be more than 90% to prevent the massive spread of infection? Of course, you can protect yourself from many infectious diseases by observing the basic rules of personal hygiene. But, unfortunately, there are diseases that can only be protected by vaccination, and when too many people refuse to carry it out, the immune stratum of the population decreases and the risk of contracting dangerous infections increases.

As long as the population continues to have a high level of vaccinated, even those who refuse to be vaccinated are protected by herd immunity, which will prevent the spread of infection. For example, a decrease in the level of vaccinations against diphtheria in the 1990s led to an epidemic outbreak, an increase in severe forms of infection, an increase in mortality among children and the appearance of cases among adults. In 2008, an epidemic of measles spread in Europe, which was caused by the accumulation of a large number of unimmunized people in society due to low vaccination coverage of the population.

By vaccinating yourself or your child, you prevent the spread of contagious diseases and protect other family and community members: those with weakened immune systems, the elderly or those with certain diseases, children who have not yet received all necessary vaccinations.

Classification of vaccines

There are several types of immunization preparations.

According to the type of pathogen

According to the main characteristics, vaccines are divided into three classes:

  1. Bacterial. Contain weakened or inactivated bacteria (brucellosis, tularemia, plague, tuberculosis). First, the bacteria are cultured on a nutrient medium. This is followed by the stage of concentration and purification (diafiltration and ultracentrifugation). Live bacterial vaccines are ready for use after freeze-drying in the presence of stabilizers. Inactivated antibacterial vaccines are subject to additional effects: inactivation, disintegration or precipitation of antigens.
  2. Viral (against smallpox, yellow fever, rabies, polio, influenza, measles, mumps). Viral strains are grown in cell cultures or chicken embryos. For inactivation of virions, ultraviolet, formalin, beta-propiolactone are used. In the case of the preparation of split or subunit vaccines, the preparation is subjected to the action of a detergent in order to destroy the viral particles.
  3. Anatoxins (toxoids) are obtained by inactivation of toxins (waste products) of pathogens. On their basis, grafting material is made against whooping cough, tetanus, diphtheria.

According to the strain of the pathogen

Vaccines are classified according to the strain of the pathogen:

  1. Alive. The basis of the drug is weakened, but living microorganisms that are not capable of causing disease, but give the immune system the opportunity to develop defense cells. Attenuation (weakening of the virulence of pathogenic microorganisms) is achieved by inactivation of the gene responsible for the virulence factor or by induced mutations in these genes. Live vaccines protect against polio, measles, rubella, influenza, mumps, varicella, tuberculosis, rotavirus infection.
  2. Inactivated vaccines contain "killed" microorganisms. They are used to form immunity against poliomyelitis, whooping cough, influenza, typhoid fever, tick-borne encephalitis, rabies, hepatitis A, meningococcal infection.
  3. Inactivated vaccines may be whole-cell (for bacteria) or whole-virion (for antiviral vaccines), or may contain only single, specially selected antigens sufficient to generate an immune response. The component is acellular, that is, acellular pertussis vaccine, which contains three antigens; Haemophilus influenzae type B vaccine containing two antigens; hepatitis B vaccine containing one antigen. Diphtheria and tetanus vaccines also contain one antigen each.
  4. Non-live vaccines also include recombinant vaccines produced by genetic engineering. They do not contain any elements of viruses or bacteria, since the active antigen is built by yeast cells.

When a vaccine is administered, the antigen of the infectious agent is presented to the human immune system in a safe form (depending on the drug: in the form of a weakened or killed microorganism, or part thereof) so that it could not cause the development of the disease. It can be said that during vaccination, immunity is trained and prepared for a possible attack of one or another pathogen of the infectious process.

After an antigen enters the body, a pool of antibodies is produced against it, this can take up to 3 weeks. Immunological memory remembers the antigen and, in case of contact with a living microorganism, inactivates it before the stage of disease development, since no time is lost for its recognition and the process of producing antibodies. The struggle begins at the stage of penetration of the pathogen into the body, before the period of its significant reproduction and the height of the disease. Therefore, in the overwhelming majority of cases, the disease does not even develop in vaccinated individuals, and contact with a pathogenic microorganism may go unnoticed.

Due to the peculiarities of the immune status and the state of the body, a vaccinated person can get sick, but vaccination will not allow a severe course and complications of the infection. The intensity and duration of post-vaccination immunity depend on the properties of the administered vaccine. The longest duration of immunity is achieved with live vaccines when the microorganism multiplies in the host (as with natural infection). An inactivated vaccine has a lower antigen load, so it does not create such a strong immune response after the first injection, and in some cases it must be administered several times. For example, revaccination against tetanus and diphtheria should be carried out every ten years. Each person should know their vaccination status and monitor it, and when the revaccination period approaches, they should independently contact a polyclinic or a specialized center, since immunity weakens over time, and the risk of infection, on the contrary, increases.

A person's serious and responsible attitude towards vaccination can guarantee him effective protection against infectious diseases.

Do vaccines form stronger immunity than natural infections

After an infection, a person develops active natural immunity. Vaccination forms active artificial immunity against a specific infection. The body produces antibodies on its own, so immunity acquired after infection or vaccination is active. During vaccination, the antigen is artificially introduced into the body, and immunity is formed against the specific infection against which the vaccination is carried out.

The immune response after vaccination is similar to the immune response to a natural infection, but without the risk of disease in the vaccinated person. In the case of some diseases, to transfer means to receive long-term or even lifelong immunity, but the cost of building immunity may be too high. In most cases, immunity after vaccination and past infection has the same duration. This is a proven fact for live vaccines against measles, mumps, rubella, varicella and polio. In people who have received such a vaccine, antibodies in protective concentrations are determined in the blood for life.

There are infections in which immunity after vaccination, if an inactivated pathogen is administered, weakens faster than natural, but the severity and outcome of the disease do not allow taking such risks. Complications of measles can lead to the development of measles encephalitis, as well as subacute sclerosing panencephalitis (severe progressive disease of the nervous system), ending in death. Complications of poliomyelitis are numerous and are associated with the development of paresis and paralysis; in some cases, gastrointestinal bleeding, perforation and intestinal obstruction are observed. Rubella transferred during pregnancy by a woman carries the risk of developing birth defects in the fetus. The outcome of infection with the hepatitis B virus can be cirrhosis and liver cancer.

Even a previous infectious disease does not guarantee lifelong immunity, and this is due to a number of factors. The causative agent of the disease can be transformed due to mutations in such a way that the immune system ceases to recognize it; the existence of antibodies in the body may be short-lived, and over time, such immunity is lost.

Is it safe to get vaccinated and why are people afraid of getting vaccinated?

The development, storage and use of vaccines is under the control of the World Health Organization and international drug safety organizations. Before a vaccine is licensed for use, it must undergo years of testing. National drug regulatory authorities scrutinize each vaccine before it is licensed, and moreover, certification is carried out separately for each batch. A system has been developed to monitor and investigate reports of any adverse events following vaccination. Once a vaccine has passed the licensing process and can be used to vaccinate the population, it continues to be monitored for safety and efficacy.

Like any drug, vaccines are not without risks and can cause side effects, including allergic reactions. To prevent a possible allergy to one or another component, complete information about the vaccine must be present in the annotation to the drug. In most cases, after vaccination, either no change in well-being follows, or acceptable reactions occur, such as fever or soreness, swelling and redness at the injection site. These reactions usually last one to two days and are characteristic of immunization with live vaccines. The measles vaccine sometimes causes a temperature reaction, runny nose, sore throat, cough, a small measles-like rash. All these symptoms disappear on their own in 2-3 days. Rubella vaccination may cause a short rash that does not require treatment and resolves on its own in 1–2 days. Temperature reactions and a slight increase in the parotid salivary glands can give a mumps vaccine. Reactions to an inactivated vaccine are extremely rare.

Many parents worry that their children are vaccinated at the hospital, and in the first year of life they are given a large number of vaccines, and sometimes the child receives several doses of different immunization drugs at the same time. Research shows that our immune system can respond to 10,000 doses of vaccines and still not "use up" its defense response.

Immunizations given in the first years of a child's life do not overload the immune system. From birth, we daily encounter and successfully cope with a huge number of microorganisms that are in the environment. Many bacteria even live with us on mucous membranes and skin. Our immune system is able to recognize and respond to millions of different antigens. We cannot overload it with the introduction of vaccines. The child's immunity will react to the vaccine in the same way as to all other antigens. Do not put off the necessary vaccinations until the child goes to kindergarten or school. This does not provide greater safety and does not guarantee the complete absence of possible adverse post-vaccination reactions. Waiting for vaccinations increases your child's risk of contracting serious diseases.

Vaccination is a concern for people prone to allergic reactions. Doctors, including pediatricians, argue that patients with allergies especially need to be vaccinated, because they are more difficult to tolerate many diseases, and the range of drugs in case of an infectious disease can be significantly limited due to drug intolerance. Of course, if a person has acute manifestations of an allergic process, the vaccination should be postponed. But as soon as allergic manifestations disappear, vaccination can be carried out. It does not lead to a worsening of the allergy, nor to the emergence of a new sensitivity to anything.

Some people are concerned about the way vaccines are given into the body by injection (shot). After all, some of them can be taken orally (through the mouth) or intranasally (through the nose). The method of administering the vaccine by injection is safe because the drug is not injected directly into the bloodstream. The injection is performed into the muscle or subcutaneous fat.

Most non-live vaccines contain additives that make them sterile, effective and safe. Information about any additional substances and preservatives in the composition of the drug has a negative impact on us. However, the extra ingredients contained in vaccines do not pose a health problem. Many of them exist naturally in our environment and in our body. They are also present in many foods and household items. Preservatives prevent changes in the properties of the vaccine. The adjuvants (auxiliaries) that are part of inactivated vaccines improve the ability of the vaccine to stimulate the body's immune system to fight the disease (increase the effectiveness of the vaccine). Stabilizers help keep the vaccine effective even if it is exposed to environmental changes such as changes in temperature or humidity. There is no evidence that any of these ingredients have harmed humans or the environment.

Vaccination calendar

Currently, Russia has a National calendar of preventive vaccinations, approved by order of the Ministry of Health of the Russian Federation No. Ministry of Health of the Russian Federation No. 370n dated 06/16/16).

The calendar includes vaccinations against 15 infections: viral hepatitis B, hemophilus, meningococcal and pneumococcal infections, influenza, diphtheria, whooping cough, measles, rubella, polio, tetanus, tuberculosis, mumps (mumps). The preventive vaccination calendar for epidemic indications also provides for vaccination against such diseases as rabies, typhoid fever, chicken pox, tick-borne viral encephalitis, meningococcal infection, anthrax, tularemia, cholera, plague, etc.

B in accordance with the National calendar, the first vaccinations for a newborn child are already done in the maternity hospital, then, starting from the age of 3 months, vaccination is carried out in a children's clinic.

Recommendations recommend vaccination against diphtheria every 10 years to maintain immunity, and against tetanus, so that tetanus toxoid does not need to be administered in case of injury.

Annual influenza vaccination is recommended.

Recommendations for vaccination

For effective vaccination, certain rules must be observed.

  1. Vaccination is carried out only by medical workers who have undergone special training in the technique of its implementation, as well as in the provision of emergency medical care.
  2. Before the procedure, the doctor conducts a mandatory examination and clarifies the timing of previous vaccinations, asks if there were contacts with infectious patients, previous diseases, including chronic, allergic reactions to drugs and food products. In some cases, before vaccination, the doctor may recommend consultations with other specialists or prescribe tests (for example, before vaccination against hepatitis B, it is necessary to take a blood test for antibodies to the hepatitis B surface antigen - anti-HBsAg).
  3. Prophylactic antihistamines (antiallergic) may only be recommended by a doctor if you have various manifestations of allergies ( urticaria, atopic dermatitis, asthma), or if a past dose vaccination caused severe swelling, redness and pain at the injection site. Prophylactic use of antipyretics is generally not recommended. The only exceptions are children who had febrile (with fever) convulsions. They should be given an antipyretic immediately before vaccination or immediately after vaccination.
  4. Be sure to ask your doctor about possible reactions after vaccination. The doctor will explain what reactions may occur and when, as well as in what cases you should seek medical help.
  5. “Informed voluntary consent for medical intervention” must be completed and signed. If your child is vaccinated, only the parents can sign such consent. Other family members are not legal representatives.
  6. Specify which vaccine will be given. Make sure that the vaccination uses drugs that are registered in accordance with Russian legislation with the correct storage, transportation conditions and not expired.
  7. Do not leave the clinic or medical center for 20-30 minutes after the procedure in case of unpredictable immediate allergic reactions to the injected substance.

What are the contraindications for vaccination

There are very few contraindications and they are established by the World Health Organization. There are absolute and relative contraindications to vaccination.

Absolute contraindications include:

  1. Any immunodeficiency condition. Immunodeficiency can be primary (hereditary) and secondary (due to illness, medication).
  2. Any complications from earlier administration of this vaccine (allergic reactions, collapse, etc.).
  3. Severe reaction to previous administration of this vaccine: fever above 39°C, infiltrate (edema) more than 8 centimeters in diameter at the injection site.
  4. All live vaccines (BCG, oral polio live, rubella, measles, and mumps) other than immunocompromised conditions are not administered in malignancy and pregnancy.

Relative contraindications include:

  1. Acute respiratory viral disease (ARVI) with high fever. In such cases, the planned vaccination is postponed for 1-4 weeks until recovery.
  2. Exacerbation of a chronic disease. Vaccination is carried out only during remission and after consultation with a specialist.
  3. After a blood transfusion or immunoglobulin administration (routine vaccination is delayed by 3 months).

In all cases, the issue of contraindications to vaccination should be decided by a doctor!

Vaccination during pregnancy and lactation (breastfeeding)

The decision to vaccinate pregnant and breastfeeding women should be taken by the doctor individually, taking into account the characteristics of the woman's health. Immunization of a woman during pregnancy is possible only with modern inactivated or recombinant vaccines. In this case, the vaccine does not affect the normal development of the fetus and does not cause unwanted post-vaccination effects. During pregnancy, live attenuated vaccines (vaccines in which strains of infectious agents are artificially weakened) should not be used. Vaccination is recommended in the second (preferably with immunoadjuvanted vaccines) and third (vaccines without adjuvants can be used) trimester of pregnancy. For vaccination, only inactivated vaccines that do not contain preservatives and are allowed in Russia should be used.

Vaccination against coronavirus

Vaccination against coronavirus began immediately in many countries. Does this mean for us a return to normal life, a rejection of social distancing and personal protective equipment?

We still do not know to what extent the current coronavirus vaccines are able to provide an immune response, stop the reproduction of the virus in the body, thereby preventing the development of the disease and the spread of infection. Now mass vaccination against COVID-19 in the world is carried out using vaccines developed on different technological platforms.

There are main types of vaccines against a new coronavirus infection ( COVID-19 ):

  1. Whole virion (inactivated and live attenuated) vaccines are obtained by growing SARS-CoV-2 in cell culture. To develop antiviral immunity, virions are introduced that are weakened or "killed" thermally or with the use of chemical agents. The mechanism of formation of immunity is close to natural. Inactivated vaccines often require the addition of adjuvants to enhance the immune response. The production of live vaccines is subject to very high biosecurity requirements, since the risk of pathogenicity of the virus remains in the live vaccine.

Inactivated vaccines include: CoronaVac from Sinovac Biotech, vaccines from the Wuhan and Beijing Institutes, and others.

The live attenuated vaccine is SpyBiotech UK.

  1. Vectored (replicating and non-replicating) vaccines. The genetic material of the virus is delivered to the body using a vector - another virus that does not cause disease in humans. In some cases, animal viruses are used that do not replicate and do not cause disease in humans. This type of vaccine is highly immunogenic. In their production, there is no need to deal with live SARS-CoV-2. The disadvantages include that if a person has antibodies to the vector virus, it may be partially neutralized, and the immune response to the target virus may not develop sufficiently. Also, immunity can be formed to the vector virus, and not to the target virus. Vector vaccines include: Gam-COVID-Vak N. F. Gamaleya (human adenovirus), CanSino (human adenovirus), Oxford/AstraZeneca (chimpanzee adenovirus).
  2. Nucleic acid vaccines (DNA and RNA vaccines).

Instead of the antigen itself, the genetic information about the antigen produced by Escherichia coli is delivered to the body. Once in the body, genetically engineered structures based on RNA and DNA, enclosed in a lipid nanoparticle, enter the cell and begin to synthesize pathogen-specific antigens that cause an immune response. Nucleic acid-based vaccines have shown great efficacy, and many are under development. But they are not yet well understood, and there is no clinical experience with DNA and RNA vaccines in humans. Ultra-low temperatures are required for their storage and transportation. For example, the BioNTech vaccine storage temperature is -70 °C.

RNA vaccines include BioNTech and Pfizer BNT162b2 and mRNA-1273 vaccines from the American company Moderna.

  1. Subunit vaccines are combinations of different antigenic components of a virus, such as synthetically produced peptides or proteins. Subunit vaccines have a low reactogenicity, since they contain only the antigens necessary for the formation of an immune response. Subunit vaccines are difficult to manufacture. The use of adjuvants and booster immunizations are often required to enhance the immune response.

WHO experts stated that they would consider any vaccine successful if it exceeds 70% effectiveness.

The American company Pfizer published data from clinical trials that their vaccine provides 95% protection against SARS-CoV-2. Moderna's messenger RNA-based vaccine has been tested with a claimed efficacy of 94.5%.

On August 11, Russia was the first in the world to register a vaccine against coronavirus. The Sputnik V vaccine was developed by the National Research Center for Epidemiology and Microbiology named after N. F. Gamaleya. The drug is based on the human adenovirus vector platform and, according to research, provides 92% protection against COVID-19. Another Russian vaccine was developed by the Novosibirsk center "Vector". At the stage of registration is the third vaccine, created by the Federal Scientific Center for Research and Development of Immunobiological Preparations. M. P. Chumakov of the Russian Academy of Sciences. The expected registration date is February 2021.

The effectiveness of vaccines against coronavirus declared by the developers exceeds 90%, which means that soon about nine out of ten vaccinated people will be protected from COVID-19.

Free vaccination against COVID-19 began in Russia in December. Even now, in many cities of Russia, virtually any person from 18 to 60 years old who has no medical contraindications and has not participated in a clinical trial can be vaccinated. Vaccination can be given to people over 18 years of age if they do not have chronic diseases listed in the list of contraindications, they have not been vaccinated in the last 30 days and have not had ARVI. Vaccination is contraindicated for pregnant and breastfeeding women. Before and after vaccination, an antibody test should be taken to track the formation of immunity to the virus.

Many people are confused by the rapid development and registration of coronavirus vaccines. Will they be able to provide the promised efficiency and safety? We do not yet know how much the result of vaccination currently taking place in the world will differ from that obtained during clinical trials of drugs. During vaccination, it is possible to identify adverse events. Allergic reactions are quite expected and likely when vaccinated with any drug. That is why people are observed for some time after the injection in order to provide medical assistance in case of an acute allergic reaction. Experts say that, despite the short development and production timelines, these vaccines have gone through the entire standard testing path and multi-stage safety control. The Ministry of Health of Russia during registration establishes requirements for the quality of the vaccine, the Ministry of Industry and Trade controls compliance with the requirements for production. Roszdravnadzor controls the quality of the vaccine in circulation, including through mandatory quality control of each batch of vaccine.

Each of us will have to choose for ourselves whether or not to get vaccinated against coronavirus, taking into account all the risks and benefits. The difficulty of choosing now is that we have to deal with new and not fully researched vaccines, and we do not yet know their possible long-term side effects.

Seasonal influenza vaccination

Seasonal influenza is a respiratory infection. The causative agent is a virus that spreads by airborne droplets and enters the mucous membranes of the nasopharynx from infected people. The disease is characterized by sudden onset, chills, fever, cough (usually dry), headache, muscle and joint pain. Anyone can get influenza. In most cases, the flu goes away after a few days, but some people may have a severe course of the disease, even death. In severe influenza, complications develop in the pulmonary system (bronchitis, pneumonia), cardiovascular system (myocarditis, pericarditis), nervous system ( meningitis, meningoencephalitis, encephalitis, polyneuropathy).

The easiest way to prevent influenza is to get vaccinated. It is best to do it before the start of the flu season, as protective antibodies are produced on average 2 weeks after vaccination. The optimal time for this procedure in Russia is from September to November. Since the virus is most active in our country from late autumn to the end of winter, full-fledged immunity after vaccination will have time to form. Children should start vaccination earlier, because for them, in order to reduce the risk of developing possible adverse reactions, the vaccine is divided into two doses, the interval between which is at least 30 days. But it is possible to get vaccinated later, since the risk of infection lasts during the entire period of active circulation of the virus among the population. Vaccination will increase the chances of effective protection against influenza and reduce the risk of developing severe consequences of the disease.

People with chronic diseases, over 65 years of age, young children and pregnant women are most susceptible to the consequences of a viral infection. In addition to these people, doctors strongly recommend that certain categories of the population be vaccinated against influenza, which include teachers, students, service and transport workers, as well as persons at occupational risk - medical workers.

The effectiveness of vaccination depends on the health and age of the person being vaccinated, as well as on the time that has elapsed since vaccination. The protective effect after the introduction of the influenza vaccine, as a rule, lasts up to 12 months. In different years, drugs can be of varying degrees of effectiveness, depending on the types of circulating virus and their compliance with the components of the vaccine. Influenza viruses are prone to frequent mutations, immunity from vaccination decreases over time, so even vaccinated people can get the flu. And in this case, vaccination in advance will be beneficial, since in vaccinated people the symptoms of the disease will be less pronounced, and the risks of developing complications will be significantly lower.

The first influenza vaccines, the so-called "live vaccines", consisted of attenuated or inactivated viruses. Almost all modern influenza vaccines are inactivated, where the virus is "killed" in a certain way and divided into fragments. Inactivated preparations can be whole-virion vaccines, which consist of purified and split influenza viruses, or split vaccines, which include the outer and inner proteins of the destroyed viruses (that is, the complete antigenic set). Subunit influenza vaccines are also used, consisting of only two viral proteins: hemagglutinin and neuraminidase. These vaccines have a minimum number of adverse reactions. The viruses used in vaccines are inactivated and do not cause influenza. Sometimes vaccinated people experience malaise, myalgia (muscle pain), a slight increase in temperature is acceptable for a couple of days after vaccination; this is a side effect in the production of antibodies and is not a complication of the vaccination.

Modern polyvalent influenza vaccine protects against 3-4 different seasonal influenza viruses (trivalent and quadrivalent vaccines). Currently produced trivalent vaccines contain two types of influenza A virions (H3N2 and H1N1) and influenza B virus of one of two lines. Vaccines that protect against four different viruses include both strains of influenza B viruses (quadrivalent vaccines). As a rule, this is enough to protect against the main strains of the influenza virus, although there are about thirty circulating types of influenza. Inactivated vaccines without a preservative can be used for vaccinations in children from 6 months of age, adolescents, adults of any age and pregnant women in the 2nd and 3rd trimesters of pregnancy. Vaccines with a preservative are used only in adults over 18 years of age. Modern vaccines are well tolerated and have high epidemiological efficiency. To ensure maximum antiviral protection, the composition of vaccines changes every year. WHO continuously collects and analyzes samples of influenza viruses from around the world and, based on these data, updates the composition of influenza vaccines annually.

Conclusions

The diseases that vaccines protect us from can lead to disability and death. Thanks to vaccination, we are no longer threatened by many of the infectious diseases and epidemics that mankind has faced in the past. To date, the most effective and proven means of preventing various infectious diseases is vaccination.

Sources
  1. Vaccination specialists. – All about vaccines.
  2. Radar encyclopedias. - Pharmacological group - vaccines, serums, phages and toxoids.
  3. Immunizations. – Classification of vaccines.
  4. Epidemiologist Soprun L. A., St. Petersburg State Budgetary Health Institution “Dental Polyclinic No. 29”.– Vaccination is important!
  5. O. A. Shamsutdinova Infection and immunity. - Live attenuated vaccines for immunoprophylaxis.
  6. V. L. Melnikov, N. N. Mitrofanova, Federal State Budgetary Educational Institution of Higher Professional Education "Penza State University" (PGU). - Vaccines, vaccination. Tutorial.
  7. School of Health - GBUZ City Polyclinic 25, Krasnodar, Ministry of Health of the KK. - Vaccination.
  8. World Health Organization (WHO). – WHO positions on vaccines.
  9. FSBI “SSC Institute of Immunology” FMBA of Russia. - Myths about vaccinations.
  10. Washington State Department of Health. – Plain and simple about vaccinations for children.
  11. FSBI “SSC Institute of Immunology” FMBA of Russia. - Vaccines of the national immunization schedule.
  12. GUARANTOR. - Appendix N 1. National calendar of preventive vaccinations.
  13. BUZ UR "Zavyalovskaya district hospital of the Ministry of Health of the UR". - Recommendations for vaccination of a child, prevention of post-vaccination reactions.
  14. FGAU "National Scientific and Practical Center for Children's Health". – Contraindications to vaccination.
  15. ​​
  16. State budgetary health care institution of the Nizhny Novgorod region "Pavlovsk central district hospital". - Memo. Recommendations to the population on vaccination and the basics of the safety of immunoprophylaxis.
  17. Stavropol State Medical University. - Vaccination.
  18. Centers for Disease Control and Prevention. – Influenza and Pregnancy Letter for Health Providers.
  19. Ministry of Health of the Russian Federation. – Recommendations for vaccination of pregnant women.
  20. Wikipedia. – Vaccine against COVID-19.
  21. Prof Yanjun Zhang, Gang Zeng, Hongxing Pan, Prof Changgui Li, Yaling Hu, Kai Chu, Weixiao Han, Zhen Chen, Rong Tang, Weidong Yin, Xin Chen, Yuansheng Hu, Xiaoyong Liu, Congbing Jiang, Prof Jingxin Li, Minnan Yang, Yan Song, Prof Xiangxi Wang, Qiang Gao, Prof Fengcai Zhu. – Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine in healthy adults aged 18–59 years: a randomised, double-blind, placebo-controlled, phase 1/2 clinical trial.
  22. Vidal's Drug Handbook.– Gam-COVID-Vac Combined vector vaccine for the prevention of coronavirus infection caused by the SARS-CoV-2 virus. Instructions for use.
  23. Hadassah Medical. – Clinical study of the Gam-COVID-Vac vaccine.
  24. Grls.rosminzdrav.ru. – Register of permits for conducting clinical trials of medicinal products.
  25. South China Morning Post. – CanSino, China’s first drug maker to start human trials for Covid-19 vaccine, soars in Star Market trading debut.
  26. Maria Deloria Knoll, Chizoba Wonodi. – Oxford–AstraZeneca COVID-19 vaccine efficacy.
  27. Fernando P. Polack, Stephen J. Thomas, Nicholas Kitchin, Judith Absalon, Alejandra Gurtman, Stephen Lockhart, John L. Perez, Gonzalo Pérez Marc, Edson D. Moreira, Cristiano Zerbini, Ruth Bailey, Kena A. Swanson, Satrajit Roychoudhury, Kenneth Koury, Ping Li, Warren V. Kalina, David Cooper, Robert W. Frenck, Laura L. Hammitt, Özlem Türeci, Haylene Nell, Axel Schaefer, Serhat Ünal, Dina B. Tresnan, Susan Mather, Philip R. Dormitzer, Uğur Şahin, Kathrin U. Jansen, and William C. Gruber. – Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine.
  28. Medscape. – COVID-19 vaccine, mRNA-Moderna (Investigational).
  29. Sara E. Oliver, Julia W. Gargano, Mona Marin, Megan Wallace, Kathryn G. Curran, Mary Chamberland, Nancy McClung, Doug Campos-Outcalt, Rebecca L. Morgan, Sarah Mbaeyi, José R. Romero, H. Keipp Talbot, Grace M. Lee, Beth P. Bell, Kathleen Dooling. – The Advisory Committee on Immunization Practices’ Interim Recommendation for Use of Pfizer-BioNTech COVID-19 Vaccine.
  30. Stopcoronavirus.rf. – Vaccination – Frequently Asked Questions.
  31. Moscow Department of Health.
  32. Rospotrebnadzor.ru. – Vaccine to prevent COVID-19.
  33. Rospotrebnadzor.ru. - Recommendations of Rospotrebnadzor to the population on vaccination.