#ScholarlyArticles – VACCINATION and IMMUNIZATION

VACCINATION AND IMMUNIZATION

Vaccination is the administration of antigenic material (an antigen – a vaccine) to stimulate an individual’s immune system to develop adaptive immunity to a disease causing organism.

Even though vaccination and immunization are often used interchangeably, especially in non-medical community, immunization appears to be the better and the more inclusive term because it implies that the administration of an vaccine actually results in the development of adequate immunity.

Vaccination is the most effective method of preventing infectious diseases; vaccines can prevent infection or minimize the impact of infectious diseases. Widespread immunity due to vaccination is largely responsible for the eradication of smallpox worldwide and for the restriction of killer diseases such as poliomyelitis, measles, tetanus, from many parts of the world.

While most people are trusting enough to allow themselves injected an unknown substance from a company by a complete stranger, a small percentage, however, choose not to be vaccinated or not to have their children vaccinated. But it’s been this way almost since Edward Jenner first began vaccinating people against smallpox, even though it’s with the help of the vaccines that smallpox was eventually eradicated from the United States by 1950 and from the entire world by 1980.

HISTORY OF VACCINATION

The modern day vaccination could be traced to the 17th century innovations of Edward Jenner who was popular for inventing the first vaccine. However, the story of vaccines dates back hundreds of years, a necessity that arose from the long history of humans struggling with infective diseases. Buddhist monks drank snake venom to confer immunity to snake bite. There are also evidences that the Chinese employed smallpox inoculation or variolation (i.e smearing their skin with cowpox/smallpox materials to confer immunity to smallpox)  as early as 1000 CE. This was practiced in Africa and Turkey as well, even before it spread to Europe and the Americas.

Edward Jenner is considered the founder of vaccinology in 1796, after he inoculated a 13 year-old-boy with vaccinia virus (cowpox), and demonstrated immunity to smallpox. And beginning with this successful creation of immunity, Edward Jenner’s innovations quickly made the practice widespread. In 1798, the first smallpox vaccine was developed. His method underwent medical and technological changes over the next 200 years,  until eventually culminated in its global eradication in 1979 following systematic implementation of mass smallpox immunization.

In 1885, Louis Pasteur invented the rabies vaccine. Louis Pasteur’s rabies vaccine was the next to make an impact on human disease. And as that period also coincided with the dawn of bacteriology (and virology), multiple developments of many antigenic vaccines rapidly followed. Antitoxins and vaccines against diphtheria, tetanus, anthrax, cholera, plague, typhoid, tuberculosis, and many other human diseases were developed through to the 20th century:  Louis Pasteur’s experiments also spearheaded the development of live attenuated cholera vaccine in 1897 and inactivated anthrax vaccine in 1904 which were used on humans. Plague vaccine was also invented in the late 19th Century. Between 1890 and 1950, bacterial vaccine development proliferated, including the Bacillis-Calmette-Guerin (BCG) vaccination, which is still in use today.

In 1923, Alexander Glenny perfected a method to inactivate tetanus toxin with formaldehyde. The same method was used to develop a vaccine against diphtheria in 1926. the development of pertussis vaccine however took a longer period, with a whole cell vaccine first licensed for use in the US in 1948.

The middle of the 20th century was an active time for vaccine research and development. Methods for growing viruses in the laboratory (i.e viral tissue culture) led to rapid discoveries and innovations, and led to the creation of the Salk (inactivated injection) polio vaccine and the Sabin (live attenuated oral) polio vaccine. Mass polio immunization has now eradicated the disease from many regions around the world. During this period, researchers also targeted other common childhood diseases such as measles, mumps, and rubella; attenuated strains of measles, mumps and rubella were developed for inclusion in vaccines, and vaccines for these diseases reduced the disease burden greatly.

Measles is currently the next possible target for elimination via vaccination. In 1954, John F. Enders and Dr. Thomas C. Peebles collected blood samples from several ill students during a measles outbreak in Boston. They wanted to isolate the measles virus in the student’s blood and create a measles vaccine. They succeeded in isolating measles in 13-year-old David Edmonston’s blood. Measles vaccine is usually combined with mumps and rubella (MMR), or combined with mumps, rubella and varicella (MMRV).It is believed that one dose of live, attenuated vaccine will give life-long protection.

Although there has been lots of controversies particularly surrounding measles and the measles vaccine, it should be noted that measles death rate had declined by almost 100% since the invention of the measles vaccine. The current MMR vaccine is said to be 93% effective. It is however unfortunate that after 60 years, measles is yet to be eradicated.

 MOLECULAR GENETICS AND VACCINATION TODAY

The past two decades have seen the application of molecular genetics and its increased insights into immunology, microbiology and genomics applied to vaccinology. Innovative techniques now drive vaccine research, with recombinant DNA technology and new delivery techniques leading scientists in new directions. Current successes include the development of recombinant hepatitis B vaccines, the less reactogenic acellular pertussis vaccine, and new techniques for seasonal influenza vaccine manufacture. Also, disease targets have expanded, and some vaccine research is beginning to focus on non-infectious conditions such as addiction and allergies.

The Application of Science Technology and medicine. Source: http://science.taskermilward.org.uk

 Molecular genetics sets the scene for a bright future for vaccinology, including the development of new vaccine delivery systems (e.g. DNA vaccines, viral vectors, plant vaccines and topical formulations), new adjuvants, the development of more effective tuberculosis vaccines, and vaccines against cytomegalovirus (CMV), herpes simplex virus (HSV), respiratory syncytial virus (RSV), staphylococcal disease, streptococcal disease, pandemic influenza, shigella, HIV, malaria and schistosomiasis among others. Therapeutic vaccines may also soon be available for cancer, allergies, autoimmune diseases and addictions.

CURRENT CHALLENGES

Human struggle with germs is endless and hence it cannot be completely halted by vaccines, no matter how great their immunological power. And also, despite advancement in vaccination and immunization, effective vaccines for many diseases remain elusive.

No discussion of vaccines is complete without discussing two world’s leading killer diseases. It is both sad and frustrating that effective vaccines for two of the world’s leading killers, HIV and malaria, remain in the research stage. Trials have provided evidence that it is possible to develop vaccines that can prevent infection by human immunodeficiency virus (HIV) and malaria but most attempts to develop these vaccines have been unsuccessful.

One of the most frustrating quests has been for a malaria vaccine. The plasmodium parasites responsible for malaria have demonstrated an impressive ability to circumvent eradication efforts by becoming drug-resistant. The development of an HIV vaccine in the twenty-first century will be a medical breakthrough; but like plasmodium, the HIV retrovirus is a wily and insidious microbe. Most attempts to develop an HIV vaccine have ended in failure.

Source: IAVI’s Integrated R&D Program: Accelerating AIDS vaccine development

TO VACCINATE OR NOT TO VACCINATE

Despite the evidence of health gains from immunization programmes, there has always been resistance to vaccines by anti-vaccination groups. The late 1970s and 1980s marked a period of increasing litigation and decreased vaccine manufacturing. And up to the present day there is still significant vaccine supply crises and continued media efforts by growing and ferocious anti-vaccination lobby.

Thus, vaccination has become an extremely controversial topic these days.

Whatever side of the aisle you may fall with regard to your opinion about vaccination, one thing is for certain. The choice to vaccinate or not to vaccinate is a decision that has the potential to greatly impact the your health and most importantly, the health of your children for the rest of their lives. Hence it is important to make informed decision and not to depend on the unfounded claims we hear and read about.

Further reading:

The History of Vaccines

The History Of Vaccines And Immunization

A brief history of vaccination

Measles and Measles Vaccine

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