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*Course Name: Principles of Microbiology for Public Health BIOL103

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( Please i need more than 500 words please)

Q) Please compose an essay addressing the following topic:

VACCINES

Discuss the role of Microbiology in context to Public health for the above topic. Explain the different uses and support provided by microbiology in Vaccination Public Health programs.

Your essay must be structured as follows:

Introduction

Body

Conclusion

I need new and unique answers, please. (Use your own words, don't copy and paste)

( Please i need more than 500 words please)

Answer 1

VACCINES

INTRODUCTION

Vaccines are substances which consist of killed or modified microbes, components of microbes, or microbial DNA that trick the body into thinking an infection has occurred. Vaccination is defined as the intentional administration of a harmless or less harmful form of a pathogen to induce a specific immune response that protects the individual against later exposure to the same pathogen.

Vaccination is the best known and the most successful application of immunological principles to human health. the first vaccine was named after vaccina, the cowpox virus. Edward Jenner pioneered its use 200 years ago. Later, Pasteur's dried rabies - infectedrabbit spinal cords and heated anthrax bacilli were the true forerunners of today's vaccines. With Burnet's clonal selection theory (1957) and the discovery of T and B - lymphocytes, the key mechanism of vaccination became clear. the incidence of diseases such as diphtheria, measles, mumps, pertusis, rubella, poliomyelitis and tetanus has declined drammatically as vaccination has become more common. Use of vaccines can save the lives of millions of infants worldwide. But, for malaria, tuberculosis and AIDS there are no effective vaccines.

Primary goal in vaccination is to provide protective immunity by inducing a memory response to an infectious microorganism using a non - toxic antigen preparation. It is important to produce immunity of the appropriate kind : antibody or cell mediated immunity. The aims of vaccination are to induce memory in T and B lymphocytes through the injection of a non - virulent antigen preparation.

CONTENT

Vaccines are made from microbes that are dead or inactive so that they are unable to cause disease. The antigen in the vaccine is the same as the antigen on the surface of the disease-causing microbe. The vaccine stimulates the body to produce antibodies against the antigen in the vaccine. The antibodies created will be the same as those produced if the person was exposed to the pathogen. If the vaccinated person then comes into contact with the disease-causing microbe, the immune system remembers the antibodies it made to the vaccine and can make them faster. The person is said to be immune to the pathogen.

Vaccines are usually given by an injection. The measles vaccine is combined with the mumps and rubella (German measles) vaccines and is given as a single injection to babies at at 12–18 months, and again at four years old. It is called the MMR vaccine. When enough people are vaccinated against a disease it is possible for that disease to be eliminated from the world, e.g. in 1980 the World Health Organization announced that smallpox had been eradicated.

Development of effective new vaccines is a long, complicated, and costly process, rarely reaching the stage of years-long clinical trials. Vaccine development begins with basic research. An appreciation of the differences in epitopes recognized by T and B cells has enabled immunologists to design vaccine candidates to maximize activation of both cellular and humoral immune responses. As diff erences in antigenprocessing pathways became evident, design strategies and additives can be employed to activate specific, desired immune pathways and to maximize antigen presentation. Targeting strategies to elicit protection at mucosal surfaces, the most common site of infection, are also underway. Finally, techniques like genetic engineering are being employed to develop vaccines that maximize the immune response to selected epitopes and that simplify delivery.

   Immunization is the process of eliciting a long-lived state of protective immunity against a disease-causing pathogen. Exposure to the live pathogen followed by recovery is one route to immunization. Vaccination , or intentional exposure to forms of a pathogen that do not cause disease (a vaccine), is another. In an ideal world, both engage antigen-specific lymphocytes and result in the generation of memory cells, providing long-lived protection.

• Passive immunization

   Passive immunization, in which preformed antibodies are transferred to a recipient, occurs naturally when maternal IgG crosses the placenta to the developing fetus. Maternal antibodies to diphtheria, tetanus, streptococci, rubeola, rubella, mumps, and poliovirus all aff ord passively acquired protection to the developing fetus. Emil Von Behring and Hidesaburo Kitasato were two investigators who contributed to passive immunization mechanism.

• Active immunization

   Whereas the aim of passive immunization is transient protection or alleviation of an existing condition, the goal of active immunization is to trigger the adaptive immune response in a way that will elicit protective immunity and immunologic memory. When active immunization is successful, a subsequent exposure to the pathogenic agent elicits a secondary immune response that successfully eliminates the pathogen or prevents disease mediated by its products. Active immunization can be achieved by natural infection with a microorganism, or it can be acquired artifi cially by administration of a vaccine. In active immunization, as the name implies, the immune system plays an active role— proliferation of antigen-reactive T and B cells is induced and results in the formation of protective memory cells. This is the primary goal of vaccination.

Active immunization by artificial means can be achieved by following strategies,

1. Attenuated organisms (avirulent).
2. Inactivated organisms (killed).
3. Purified microbial macromolecules.
4. Cloned microbial antigens.
5. Synthetic peptides.
6. Anti - idiotype antibodies.
7. Multivalent complexes.

When active immunization is successful, a subsequent exposure to the pathogenic agent elicits a heightened immune response that successfully eliminates the pathogen or at least prevents disease mediated by its products.

Active immunization with various types of vaccines has played an important role in the reduction of deaths from infectious diseases, especially among children. Vaccination of children is begun at about 2 months of age.

Vaccine	Birth - 1 month	2 months	4 months	6 months	12 months	15 months	18 months	4-6 years
Hepatitis B	+	+			+
Diphtheria, tetanus, pertusis	+	+	+			+	+
H.influenzae, type b	+	+	+	+
Polio virus		+	+		+
Rotavirus		+	+	+
Measles, Mumps, Rubella					+			+
Varicella						+

Recommended Childhood Immunization Schedule

Vaccination of adults depends on the risk group. For military recruits, international travellers, animal keepers, military personnel and civilians are given vaccination according to their area of exposure.

Vaccination is not 100% effective. Some recipients will respond poorly to the vaccines. Here, when the majority of population is immune to a particular infectious agent. So infection is not easy. Chance to a susceptible individual contacting an infected individual is so low. this phenomenon is called as " herd immunity". if the number of immunized individuals decreases sufficiently, because of reduction in vaccination rates, then herd immunity no longer operates to protect susceptible individuals and infection may spread rapidly in a population, leading to an epidemic.

Designing vaccines for Active immunization

Before designing any vaccine, immunologists should study properly the activation of humoral and cell mediated immune response shown by a particular antigen and secondly, the development of immunologic memory by the particular antigen. For example, vaccines may produce a protective primary response but may fail to produce immune memory cells. In this case, the individual becomes susceptible to the second infection by the same pathogen.

Various types of vaccines designed with specific characteristics

Whole organism vaccines - Many of the present day vaccines consist of bacterial cells or viral particles and these can be applied as either inactivated (killed) or live but attenuated (avirulent) forms.

• Attenuated bacterial or viral vaccines - for the production of attenuated (avirulent) vaccine, virulent pathogen is grown under adverse culture conditions or prolonged passage of a virulent human pathogen through different hosts. By these methods an avirulent organism is selected. These vaccines generally require only a single booster. Attenuated vaccines are less stable and produce humoral and cell mediated immunity. These may revert to virulent form. Eg; with Mycobacterium bovis an attenuated strain called Bacillus Calmette Guerin (BCG) was developed on a medium containing increased concentration of bile. This is suitable as a vaccine for Tuberculosis.
• Inactivated viral or bacterial vaccines - they are produced by inactivation of a virulent pathogen by means of chemical or irradiation with gamma rays. These vaccines require multiple boosters. Eg : salk polio vaccine, pertussis vaccine

CONCLUSION

On the whole, vaccinations induce a net benefit to society. Vaccines are often noted for their high return on investment (ROI) values, especially when considering the long-term effects. Some vaccines have much higher ROI values than others. Studies have shown that the ratios of vaccination benefits to costs can differ substantially - from 27:1 for diphtheria/pertussis, to 13.5:1 for measles, 4.76:1 for varicella, and 0.68–1.1 : 1 for pneumococcal conjugate. Some governments choose to subsidize the costs of vaccines, due to some of the high ROI values attributed to vaccinations. The United States subsidizes over half of all vaccines for children, which costs between $400 and $600 each. Although most children do get vaccinated, the adult population of the USA is still below the recommended immunization levels. Many factors can be attributed to this issue. Many adults who have other health conditions are unable to be safely immunized, whereas others opt not to be immunized for the sake of private financial benefits. Many Americans are underinsured, and, as such, are required to pay for vaccines out-of-pocket. Others are responsible for paying high deductibles and co-pays. Although vaccinations usually induce long-term economic benefits, many governments struggle to pay the high short-term costs associated with labor and production. Consequently, many countries neglect to provide such services.