fb-img Brains Super Speciality Hospital
Brains Super Speciality Hospital

Dr. NK Venkataramana, Founder Chairman & Director, Brains Super Speciality Hospital, Bengalru.

The story of vaccines is one of the fascinating discoveries in the field of medicine, particularly in bacteriology. The proposition of a specific infective agent responsible for specific infection itself is a great discovery. Later, development of science that enabled the identification of bacteria, their characteristics paved the way for the possibility of vaccines. Subsequent ability to isolate specific proteins added specificity to the whole mission. Thus the concept of infectious diseases has evolved into an advanced speciality. Based on the information diagnosis, culture methods, ability to choose specific antibiotic as well as vaccination as a premier method of prevention got stablished.

Historical evidence shows that the Chinese employed smallpox inoculation as early as 1000 CE. Later the same was said to be practiced in Africa and Turkey, before it spread to Europe and the America. Edward Jenner in 1796 used cowpox material to create immunity to smallpox. His method underwent several medical and technological refinements over the next 200 years, and became successful in eradication of smallpox.

Louis Pasteur in 1885 created rabies vaccine next to make a notable impact on human disease. The dawn of bacteriology, opened a range of developments identifying antitoxins and vaccines against diphtheria, tetanus, anthrax, cholera, plague, typhoid, tuberculosis in the 1930s. The 20th century was a golden time for vaccine research and development. Methods for culturing viruses in the laboratory led to rapid discoveries and innovations, including the creation of vaccines for polio. Scientists targeted many common childhood diseases such as measles, mumps, rubella, and vaccines for these diseases that has reduced the disease burden along with contributing to their health in huge proportions. Edward Jenner, Louis Pasteur, and Maurice Hilleman, the pioneers in vaccine development did receive specific attention. The first vaccine created in a laboratory was by Louis Pasteur in 1879 for chicken pox and era.

Concomitant science and innovative techniques now drive the vaccine research, with recombinant DNA technology and new delivery techniques opening the new directions like never before.

How Vaccines Work

The immune system is made up of a specialized network of organs, cells and tissues that work together to help protect against disease. When a disease causing germ (a virus or bacteria) enters the body, the immune system: recognizes the germ as being foreign, Responds by making special proteins (called antibodies) that help destroy the germ, Remembers the germ that caused sickness and destroy it before the illness starts or affects the body next time. This protection is called immunity.

Vaccines give immunity to the body from a disease without making one sick. They are made using killed or weakened versions of the disease-causing germ or parts of the germ (antigens). For some vaccines, genetic engineering is used to make the antigens and then used in the vaccine. It’s much safer to get a vaccine than to get the disease. When a vaccine is administered; the immune system responds to the vaccine, the same way as it would to the real germ.

Hence it recognises the germ in the vaccine as foreign and immediately responds by making antibodies to the germ in the vaccine, just as it would for the real germ. Then it also remembers as a special memory. If one ever gets exposed to the disease causing germ in future, the immune system will be able to quickly destroy it before it has a chance to produce the illness. This is how one gets immunity from the vaccines. Several basic strategies are used to make vaccines.

Using this strategy, viruses are weakened so they reproduce very poorly once inside the body. Hence they fail to produce full-fledged disease. The advantage of live, "weakened" vaccines is that one or two doses provide immunity that is usually life-long.

In this method viruses are completely inactivated (or killed) with a chemical. By killing the virus, it cannot possibly reproduce itself or cause disease.

The benefits of this approach are the vaccine cannot cause even a mild form of the disease and it can be given to people with weakened immune systems, but the limitation of this approach is that it typically requires several doses to achieve immunity.

Here just one part of the virus is removed and used as a vaccine like the protein that resides on the surface of the virus. This strategy can be used when an immune response to one part of the virus (or bacteria) is responsible for protection against disease.

Some bacteria cause disease by making a harmful protein called toxin. Several vaccines are made by taking toxins and inactivating them with a chemical called “Toxoid”. Due to inactivation of the toxin, it can no longer cause the disease.

Another strategy to make a bacterial vaccine is to use part of the sugar coating (or polysaccharide) of the bacteria. Protection against infection by certain bacteria is purely based on immunity to this sugar coating. Howeversince young children don't make a very good immune response to the sugar coating alone, the coating is linked to a harmless protein (this is called a "conjugated polysaccharide" vaccine).

Just like for inactivated viral vaccines, bacterial vaccines can be given to people with weakened immune systems, but often require several doses to induce adequate immunity.

Using this specialised method the vaccinated individual makes part of the virus. The vaccines for Covid 19 are made this way. The vaccine contains messenger RNA (mRNA), which is the code, or blueprint, for the spike protein of the SARS-CoV-2 virus. The vaccinated person’s muscle cells use the blueprint to make the spike protein from the surface of the virus. Once the immune system realizes this protein is “Foreign”, it creates an immune response against it, including immunologic memory. Next time, when the person is exposed to the virus, the immune system is ready to respond rapidly.

As mentioned earlier, there are five main types of vaccines: attenuated (live) vaccines, inactivated vaccines, toxoid vaccines, subunit vaccines, and conjugate vaccines.

Manufacturing vaccines is a complex journey. It takes between 7 to 36 months to produce, package and deliver vaccines. It includes testing each batch of vaccine at every step of its journey, and repeat quality control of batches by different authorities using standard methods. Manufacturing vaccine is a biological process where a very high level of expertise is required. Especially when it is given to healthy people for prevention; one must be doubly sure about its safety and efficacy. Thanks to the technology and relentless efforts of scientists that they are able bring the vaccine in the shortest possible time using all possible innovative methods. They have not only toiled but also burnt the midnight oil to achieve this goal. Hence we are able to cope with the challenge the world is facing today. This needs and deserves tremendous applause and appreciation. Everyone should contribute their mite to support such cause and also to ensure the safety of the world. Making baseless rumours and unscientific comments is untenable. We must refrain such sensationalising activity. This can mislead people and certainly disappoint science in general and scientists in particular.