Updated: Jul 10
A vaccine is a biological preparation that induces active acquired immunity against a specific infectious illness. A vaccination usually comprises an agent that looks like a disease-causing bacteria and is commonly manufactured from weakened or deceased versions of the microbe, its toxins, or one of its surface proteins. The agent induces the body's immune system to detect and eliminate the agent as a threat, as well as to recognise and destroy any microbes connected with that agent that it may meet in the future.
The phrases vaccine and vaccination are derived from Variolae vaccine (cowpox), a name coined by Edward Jenner (who discovered the idea of vaccinations as well as developed the first vaccine) to describe cowpox.
In 1798, he used the phrase as the long title of his Inquiry into the Variolae vaccine Known as the Cow Pox, in which he described cowpox's protective effect against smallpox.
To commemorate Jenner, Louis Pasteur suggested in 1881 that the words be expanded to include the new defensive inoculations that were being developed at the time.
Vaccinology is the study of vaccine discovery and manufacture.
Vaccines are usually made up of attenuated, inactivated, or dead organisms, or purified compounds generated from them. Vaccines come in a variety of forms. These are many tactics used to try to lower the risk of sickness while yet being able to elicit a favourable immunological response.
1. Attenuated Vaccine
Some vaccines contain live, attenuated microorganisms. Many of these are active viruses that have been cultivated under conditions that disable their virulent properties, or that use closely related but less dangerous organisms to produce a broad immune response. Although most attenuated vaccines are viral, some are bacterial in nature. Examples include the viral diseases yellow fever, measles, mumps, and rubella, and the bacterial disease typhoid.
There are various advantages and downsides to using attenuated vaccinations. Attenuated, or live, weakened, vaccinations often elicit more long-lasting immune responses. However, they may not be safe for use in immunocompromised people and, on rare occasions, evolve into a virulent form that causes illness.
2. Inactivated Vaccine
Some vaccinations contain inactivated but formerly pathogenic microorganisms killed using chemicals, heat, or radiation — "ghosts" with intact but empty bacterial cell envelopes. They are regarded as a transitional stage between inactivated and attenuated vaccines.
IPV (polio vaccine), hepatitis A vaccine, rabies vaccine, and the majority of influenza vaccinations are examples.
3. Subunit Vaccine
A subunit vaccine, as opposed to presenting an inactivated or attenuated microorganism to an immune system (which would constitute a "whole-agent" vaccination), employs a fraction of it to generate an immunological response.
One example is the subunit vaccination against hepatitis B, which is made up of simply the virus's surface proteins (previously extracted from the blood serum of chronically infected patients but now produced by recombination of the viral genes into yeast).
Toxoid vaccines are manufactured from inactivated poisonous chemicals that, rather than the microorganism, cause sickness. Tetanus and diphtheria vaccines are two examples of toxoid-based vaccinations. Not all toxoids are used to kill microorganisms;
for example, Crotalus atrox toxoid is used to protect dogs against rattlesnake attacks.
Heterologous vaccinations, often known as "Jennerian vaccines," are vaccines containing pathogens from other species that either do not cause disease or produce only minor disease in the creature being treated.
Jenner's use of cowpox to defend against smallpox is a typical example.
An mRNA vaccine (or RNA vaccine) is a unique form of vaccination made out of nucleic acid RNA packed in a vector such as lipid nanoparticles. A variety of RNA vaccines are being developed to prevent the COVID-19 pandemic, and several have been licenced or have gained emergency use authorisation in various countries.
In the United States, for example, the Pfizer-BioNTech vaccine and the Moderna mRNA vaccine are both licenced for use in adults (with the Pfizer vaccination additionally completely approved for teenagers aged 16 to 17).
DNA vaccination - The hypothesised technique involves inserting and expressing viral or bacterial DNA in human or animal cells (improved by electroporation), which triggers immune system recognition. Some immune system cells that detect the proteins produced will launch an attack on these proteins and the cells that express them.
Because these cells persist for a very long period, if the pathogen that typically produces these proteins is found later, the immune system will target them immediately.
One possible advantage of DNA vaccines is their ease of production and storage.
ZyCoV-D was granted emergency status by Indian authorities in August 2021. It is the first DNA vaccination authorised for human use, developed by Cadila Healthcare.
Drugs Controller General of India is the head of the department of the Central Drugs Standard Control Organization of the Government of India responsible for approval of licences of specified categories of drugs such as vaccines AND others like blood and blood products, IV fluids, and sera in India.
Building a vaccine production plant, which includes highly specialised equipment, clean rooms, and containment rooms, may cost anywhere from $50 to $500 million, depending on the antigen. Personnel with the proper combination of skills, expertise, knowledge, competence, and personality to staff vaccine production lines are in short supply across the world.
With the noteworthy exceptions of Brazil, China, and India, many developing nations' educational systems are unable to offer enough competent applicants, forcing vaccine manufacturers headquartered in such countries to acquire foreign workers to maintain production.
Vaccine manufacture is divided into various phases. To begin, the antigen is created. Viruses are cultivated on either primary cells such as chicken eggs (for influenza, for example) or continuous cell lines such as cultured human cells (e.g., for hepatitis A).
Bioreactors are used to cultivate bacteria (e.g., Haemophilus influenzae type b). Similarly, in yeast, bacteria, or cell cultures, a recombinant protein obtained from viruses or bacteria can be produced.
After the antigen has been produced, it is extracted from the cells that produced it. A virus may need to be inactivated, and no additional purification may be necessary. Many techniques requiring ultrafiltration and column chromatography are required for recombinant proteins. Finally, adjuvants, stabilisers, and preservatives are added as needed to the vaccination.
The adjuvant boosts the immune response to the antigen, stabilisers extend the shelf life, and preservatives allow for the use of multidose vials. Combination vaccines are more difficult to develop and manufacture due to potential incompatibilities and interactions between the antigens and other chemicals.
Fill and finish, the process of filling vials with vaccinations and packing them for distribution, is the final stage in vaccine manufacturing before distribution.
Although this is a seemingly basic step in the vaccine manufacturing process, it is frequently a bottleneck in the distribution and administration of vaccinations.
The Kingdom of Bavaria became one of the first countries to introduce compulsory vaccination.
UPS AND DOWNS
There has been an incidence of vaccines failing, such as in 1995 when some batches of polio vaccines given to the public contained live poliovirus, resulting in over 250 cases of polio and many cases of paralysis.
In 2017, the Philippines stopped a school-based dengue fever vaccination program after reports of several deaths.
WORLD IMMUNIZATION WEEK (APRIL 24-30)
The WHO celebrates World Immunization Week in the last week of April, with the aim of highlighting the need for collective action and promoting the use of vaccines to protect people of all ages against disease.
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