Vaccination Principle, Types and Application

Introduction:
Vaccination is a critical tool for preventing the spread of infectious diseases. In this presentation, we will explore the science behind vaccines, their impact on public health, and some of the challenges and controversies surrounding vaccination.

Section 1: Basics of Vaccination
- We will start by discussing the basic principles of vaccination, including how vaccines work, the different types of vaccines, and how they are developed and tested.
- We will also explore some common vaccine ingredients and their safety profile.

Section 2: History and Impact of Vaccination
- Vaccines have had a profound impact on public health, helping to eradicate or control many deadly diseases, such as smallpox, polio, and measles.
- We will discuss the history of vaccination and some of the major milestones in vaccine development and deployment.
- We will also look at the current state of vaccine-preventable diseases around the world and the role of vaccination in reducing their burden.

Section 3: Vaccine Controversies and Challenges
- Vaccination has not been without controversy, with some individuals and groups expressing concerns about vaccine safety, efficacy, and mandatory vaccination policies.
- We will explore some of the most common vaccine myths and misconceptions and the scientific evidence behind them.
- We will also discuss some of the challenges facing vaccination programs, such as vaccine hesitancy, access, and equity.

Conclusion:
Vaccination is one of the most effective ways to prevent the spread of infectious diseases and protect public health. Despite some challenges and controversies, vaccines have a proven track record of safety and efficacy. As we continue to face new and emerging infectious threats, vaccination will remain a critical tool in our fight against disease.

1. SRI PARAMAKALYANI COLLEGE (RECREATED WITH A GRADE WITH CGPA OF 3.39 IN THE YEAR III CYCLE OF NAAC ) Affiliated to Manonmanium Sundaranar University ALWARKURICHI-627412 POST GRADUATE & RESEARCH DEPARTMENT OF MICROBIOLOGY (government aided) ACADEMIC YEAR 2023-2024 II SEM CORE : IMMUNOLOGY UNIT 5 - VACCINATION SUBMITTED TO: DR.S.VISWANATHAN HEAD OF THE MICROBIOLOGY DEPARTMENT SUBMITTED BY: PRIYADHARSHINI.G 1 st Msc.MICROBIOLOGY

2. CONTENTS Introduction Vaccination principle Types of vaccination Applications

3. Introduction : Vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins.
The agent stimulates the body’s immune system to recognize the agent as foreign, destroy it, and “remember” it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.

4. History: Edward Jenner (1749 – 1823) was an English physician who observed that dairymaids who had had cowpox did not get small pox. He then vaccinated James Phipps, a boy of eight, with matter from cowpox. After several weeks, it became apparent that, because the boy had been inoculated, he did not contract smallpox. Jenner then published his results in Inquiry into the Cause and Effects of the Variolae Vaccinae (1798), thus proving the worth of vaccination ( Vacca – cow).

5. Time line of vaccines : 18 th century : 1796 First vaccine for smallpox , first vaccine for any disease 19 th century : 1882 First vaccine for rabies 20 th century : 1932 First vaccine for yellow fever 1945 First vaccine for influenza 1952 First vaccine for polio 1954 First vaccine for Japanese encephalitis 1957 First vaccine for adenovirus-4 and 7

6. Time line of vaccination : 1962 First oral polio vaccine 1964 First vaccine for measles 1967 First vaccine for mumps 1970 First vaccine for rubella 1974 First vaccine for chicken pox 1977 First vaccine for pneumonia 1978 First vaccine for meningitis 1981 First vaccine for hepatitis B 1992 First vaccine for hepatitis A 1998 First vaccine for rotavirus

7. An ideal vaccine should be : Good immune response: Both Cell Mediated Immunity and antibody responses. Immunity is long lived.
Single dose Safety : Danger of reversion to virulence, or Severe disease in immunocompromised

8. Stability: Organisms in the vaccine must remain viable in order to infect and replicate in the host
Vaccine preparations are therefore very sensitive to adverse storage conditions Maintenance of the cold chain is very important. Expense: Cheap to prepare

9. PRINCIPLE: The basic principle of vaccination is ‘memory’ of the immune system. Vaccines let the immune system to learn how to fight the future onslaught of that pathogen for which vaccine is being given. The body prepares antibodies in response to vaccination and remembers this act.

10. Major sites for viral replication: Mucosal surfaces of respiratory tract and GI tract. Infection at mucosal surfaces followed by spread systemically via blood and/or neurones to target organs. Direct infection of blood stream via needle or bites and then spread to target organs.

11. What happens when a vaccine enters into our body ? https://youtu.be/Atrx1P2EkiQ

12. CHILDHOOD IMMUNIZATION SCHEDULE:

13. Introduction of measles vaccine in 1662 :

14. There are several different types of vaccines. Each type is designed to teach your immune system how to fight off certain kinds of germs—and the serious diseases they cause. When scientists create vaccines, they consider: #.How your immune system responds to the germ
#.Who needs to be vaccinated against the germ
#.The best technology or approach to create the vaccine Based on a number of these factors, scientists decide which type of vaccine they will make. There are several types of vaccines, including: 1Live-attenuated vaccines. 5.Conjugate vaccines
2.Inactivated or killed. 6.DNA vaccines
3.Toxoid vaccine. 7.Recombinant vaccine.
4.Subunit vaccine.

15. Live attenuated vaccine : Live attenuated vaccines are a type of vaccine that contain live, weakened forms of the pathogen. These vaccines are created by attenuating or weakening the pathogen in the laboratory so that it can no longer cause disease, but can still stimulate a protective immune response. Live attenuated vaccines have several advantages over other types of vaccines. They typically provide longer-lasting immunity than inactivated or subunit vaccines, and they often require fewer doses to achieve immunity. Additionally, live attenuated vaccines can stimulate a broader range of immune responses, including both humoral (antibody-mediated) and cellular (T cell-mediated) immunity.

16. However, there are also some limitations to live attenuated vaccines. Because they contain live, albeit weakened, forms of the pathogen, there is a small risk of the vaccine causing disease in individuals with weakened immune systems, such as those with HIV/AIDS or undergoing chemotherapy. Additionally, live attenuated vaccines must be stored carefully, as they can lose their effectiveness if they are not kept at the appropriate temperature or if they are exposed to certain chemicals. Examples of live attenuated vaccines include the measles, mumps, and rubella (MMR) vaccine, the varicella (chickenpox) vaccine, the yellow fever vaccine, and the oral polio vaccine (OPV). These vaccines have been highly effective in preventing the spread of the diseases they target and have contributed significantly to global public health efforts.

17. Progress towards the World wide eradication of polio :

18. Inactivated vaccines: Inactivated vaccines are created by inactivating or killing the pathogen responsible for a particular disease. The inactivation process is usually achieved by chemical or physical means such as formalin, heat, or radiation.
The inactivated pathogen is then purified and formulated into a vaccine. Because the pathogen is killed, it cannot replicate in the host and cause disease. However, it retains its antigenic properties, which means it can still induce an immune response in the host. Inactivated vaccines generally require multiple doses to achieve optimal immunity. This is because the killed pathogen does not replicate and persist in the host, so the immune system needs repeated exposure to build up a strong and long-lasting response. In some cases, booster doses may be required years later to maintain immunity.

19. Inactivated vaccines have some advantages over live attenuated vaccines, which are created by weakening the pathogen. Because inactivated vaccines do not contain live pathogens, they can be given safely to immunocompromised individuals who may not be able to receive live vaccines. Inactivated vaccines also do not cause disease in the host, which is a concern with some live vaccines. Examples of inactivated vaccines include the polio vaccine, which contains inactivated poliovirus, the hepatitis A vaccine, which contains inactivated hepatitis A virus, and the influenza vaccine, which contains inactivated or fragmented influenza virus. Inactivated vaccines can also be used for other diseases, such as rabies and pertussis.

20. Toxoid vaccine : Toxins are produced by some bacteria and can cause significant damage to the host’s tissues and organs. Toxoid vaccines are created by treating the bacterial toxin with formalin or other chemicals to inactivate its toxic properties while preserving its ability to stimulate an immune response.
When a toxoid vaccine is injected into a host, it stimulates the production of antibodies that can recognize and neutralize the toxin. The antibodies are specific to the toxin, not the bacterium that produces it.
Toxoid vaccines are typically given in multiple doses to build up immunity. Booster doses may be required to maintain immunity over time.

21. Examples of toxoid vaccines include the tetanus vaccine and the diphtheria vaccine. The tetanus vaccine contains inactivated tetanus toxin, while the diphtheria vaccine contains inactivated diphtheria toxin.
Toxoid vaccines have several advantages over other types of vaccines. They are effective at preventing disease caused by bacterial toxins, which can be very dangerous. They also do not contain live pathogens, so they can be given safely to immunocompromised individuals. In addition, they do not cause the disease they protect against, unlike some live vaccines. Toxoid vaccines are an important tool in the prevention of bacterial diseases caused by toxins.

22. Subunit vaccine: Subunit vaccines are a type of subunit antigen-based vaccine that contain purified components of the pathogen, rather than the entire microorganism. This type of vaccine is often safer than traditional vaccines, as it does not contain live or inactivated pathogens that can cause disease. Subunit vaccines are often used for viruses and bacteria that have complex structures, and for which it is difficult to produce effective whole-pathogen vaccines. Subunit vaccines are typically composed of purified proteins, protein fragments, or polysaccharides from the pathogen, which are chosen based on their ability to elicit a strong immune response.

23. There are several advantages of subunit vaccines over whole-pathogen vaccines. First, subunit vaccines can be produced using recombinant DNA technology, which allows for large-scale production of purified antigens. Second, subunit vaccines are generally safer than whole-pathogen vaccines, as they do not contain live or inactivated pathogens that can cause disease. Third, subunit vaccines are often more stable than whole-pathogen vaccines, as the purified antigens are less prone to degradation. However, there are also some disadvantages to subunit vaccines. One major disadvantage is that purified antigens may not elicit as strong of an immune response as whole-pathogen vaccines, as they lack many of the other components of the pathogen that can stimulate the immune system. To address this issue, adjuvants are often added to subunit vaccines to enhance the immune response. Examples of subunit vaccines include the human papillomavirus (HPV) vaccine, which contains virus-like particles that mimic the structure of the virus, and the hepatitis B vaccine, which contains a protein from the virus. In summary, subunit vaccines are a promising approach to vaccination that offers several advantages over traditional whole-pathogen vaccines, but may require the use of adjuvants to elicit a strong immune response.

24. Conjugate vaccine : A conjugate vaccine is a type of vaccine that uses a carrier protein to link a small molecule antigen to a larger molecule that can elicit a stronger immune response. The conjugation of the antigen to the carrier protein makes it more immunogenic and enables the immune system to recognize and respond to the antigen more effectively. The development of conjugate vaccines was driven by the need to protect against encapsulated bacteria, which have polysaccharide capsules that are poorly immunogenic in young children and immunocompromised individuals. Polysaccharides are long chains of sugars that are highly variable and difficult for the immune system to recognize as foreign. As a result, polysaccharide antigens are not very effective in stimulating an immune response on their own.

25. To overcome this problem, researchers conjugate the polysaccharide antigen to a protein carrier that is highly immunogenic, such as tetanus toxoid or diphtheria toxoid. The conjugation of the antigen to the carrier protein creates a hybrid molecule that is more easily recognized by the immune system. This enhances the ability of the immune system to generate an effective immune response against the polysaccharide antigen. Conjugate vaccines have been highly effective in protecting against bacterial infections, such as meningitis, pneumonia, and sepsis. Examples of conjugate vaccines include the Haemophilus influenzae type b ( Hib ) vaccine, the pneumococcal vaccine, and the meningococcal vaccine. Overall, the conjugate vaccine technology has been a major advance in vaccine development, enabling the creation of vaccines that are highly effective in protecting against bacterial infections, especially in populations that are most vulnerable to these infections.

26. A conjugate vaccine protects against Haemophilus influenzae type b (Hib) :

27. DNA vaccine : DNA vaccines are a type of vaccine that utilizes DNA as the immunizing agent. The DNA vaccine encodes a gene for a specific antigen that is expressed in vivo, leading to the production of the antigen by the host cells. The antigen produced by the host cells is then presented to the immune system, which generates an immune response against the antigen. The DNA vaccine is constructed by cloning the gene for the antigen of interest into a plasmid vector that can replicate in bacterial cells. The plasmid is then purified and injected into the host, where it is taken up by host cells. Once inside the host cells, the plasmid vector is transcribed and translated into the antigen protein, which is then presented on the cell surface to the immune system.

28. DNA vaccines have several advantages over traditional vaccines. They are relatively easy to produce and can be manufactured rapidly in response to emerging infectious diseases. They are also stable and can be stored for extended periods of time without the need for refrigeration. Additionally, DNA vaccines can induce both humoral and cellular immune responses, making them a promising tool for the development of vaccines against a wide range of infectious diseases, as well as cancer. However, there are also some limitations to the use of DNA vaccines. One challenge is the need for efficient delivery of the DNA into host cells. This can be achieved through various methods, such as electroporation or the use of viral vectors, but these methods can be expensive and may pose safety concerns. Another challenge is the potential for immune tolerance to the antigen encoded by the DNA vaccine, which could limit the efficacy of the vaccine over time. Despite these challenges, DNA vaccines have shown promise in preclinical and clinical studies and represent an exciting area of vaccine research and development.

29. Recombinant vaccine: Recombinant vaccines are a type of vaccine that uses genetically engineered proteins or virus-like particles (VLPs) as the immunogen . Recombinant vaccines are produced by inserting the gene encoding the antigen of interest into a vector, such as a plasmid or virus, which is then used to express the antigen in a host cell. The resulting recombinant protein or VLP is then purified and used as the immunizing agent. One advantage of recombinant vaccines is that they can be produced in large quantities using well-established biotechnology methods, which enables rapid scaling up of production to meet the demand for the vaccine. Additionally, recombinant vaccines are generally safe and well-tolerated, since they do not contain live organisms.

30. Recombinant vaccines have been developed against a variety of infectious diseases, including hepatitis B, human papillomavirus (HPV), and influenza. For example, the hepatitis B vaccine is produced using recombinant DNA technology to express the viral surface antigen in yeast cells. The HPV vaccine is produced using recombinant technology to express virus-like particles that mimic the structure of the virus, but are non-infectious. One challenge with recombinant vaccines is that they may not generate the same level of immune response as a live attenuated vaccine, since they only present a small part of the pathogen to the immune system. To overcome this challenge, recombinant vaccines may be combined with adjuvants, which are substances that enhance the immune response to the vaccine antigen. Overall, recombinant vaccines represent a promising area of vaccine research and development, as they offer a safe and effective alternative to traditional vaccine approaches.

31. Production of vaccine using a recombinant vaccinia vector :

32. Advantages of Vaccination: It is used to induce long term humoral as well as cell-mediated immune response against disease-causing pathogens. Vaccines help in developing immunity against specific diseases.
It initiates a primary immune response, generating memory cells without making a person ill. Later, if the same or very similar pathogens attack, a specific memory cell already exists. They recognize the antigen and evoke secondary immune response producing large numbers of antibodies that quickly overpower the invaders.

33. The immune system is strongest in adulthood that means infants; children and elderly are particularly susceptible to a dangerous infection. Vaccines strengthen their immune system and bypass this risk.
The use of vaccines has been effective in developing resistance of infection of microorganisms that cause cholera, diphtheria, measles, mumps, whooping cough, rabies, smallpox, tetanus, typhoid, yellow fever and poliomyelitis.
Vaccines can be a key tool in managing threat or pandemic situations such as Covid-19 caused by a coronavirus.

34. Stability Efficacy Low cost production Safety Effective Long lived immunity Compatible with local Management practices Induces mucosal & humoral cell mediated response VACCINE

35. Reference: KUBY Immunology 7 th edition https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/vaccine-safety-6-common-questions-answered Medical Microbiology and Immunology 2 nd edition Prescott’s Microbiology 12 th Edition

36. Thank you