Isn’t it scary to know that we encounter 60,000 germs and approx? 5000 viruses, counting the very least, every single day. Well, it is more intriguing than scary. If the number of pathogens trying to kill us is so huge-Why isn’t the human population all dead by now?
The answer to this question resided within our very own bodies. It is the immunity system that stands tall and brave to any incoming imposter. The antibodies as we all know are the heroes of our tale. But what if we must gear up our bodies to fight a tyrant? It’s simple. We’ll have to provide external man-made help to our system.
In this article today, we are discussing this very human–aid – Advanced vaccine. Let’s begin discussing the basics of the advanced facts and figures about vaccines, their origin, advancements, and other mind-bending stats.
1. What are Vaccines?
What is the first thing that comes to our minds when we hear the term “vaccine”? A syringe or an injection with a crying baby. The imagery is quite accurate. But let us look at the more scientifically correct picture.
Biologists define vaccines as a biological preparation or solution which stimulates the immune system of the recipient. In layman’s language, vaccines are pre-prepared potions that are designed for specific diseases. These potions are made in such a way that they compel the receiver’s immune system to function under its influence and thereby build immunity.
The World Health Organization defines vaccination as “Vaccination is a simple, safe, and effective way of protecting you against harmful diseases before you come into contact with them. It uses your body’s natural defences to build resistance to specific infections and makes your immune system stronger.”
2. How do Vaccines Function?
Now, let us dig deeper into the working of these medical marvels.
2.1. Introduction of the Antigen
As we know, the primary goal of a vaccine is to prime the immune system so that it can recognize and respond rapidly and effectively to a specific pathogen if the person is later exposed to it.
For serving this purpose we manufacture vaccines using either weakened or inactivated forms of the pathogen, parts of the pathogen, or sometimes even substances that resemble the pathogen’s antigens.
These antigens are introduced into the body through injection or oral administration. However, these days we even have nasal sprays or other more convenient routes available.
2.2. Recognition by the immune system
The human body is a masterpiece. It can differentiate its cells from any foreign ones. The immune system recognizes the antigens (of the pathogen) as foreign invaders and begins to mount a response.
2.3. Activation of Immune Cells
Once the immune system is aware of the pathogen entry, it starts with the immunological response. You will be surprised to know that this physiological response has more than 20 cells involved.
Antigen-producing cells such as macrophages, dendritic cells, and B cells are the main ones in the process. These cells capture and present the antigens to T cells.
This process activates the immune cells and triggers an immune response. By immune response, we are referring to the creation of antibodies. Technically speaking, Antibodies are proteins that can bind specifically to the antigens present on the surface of the pathogen.
2.4. Destruction of the Pathogen
Antibodies produced in response to the vaccine bind to the antigens on the surface of the pathogen. This attachment now makes the pathogenic cells different from the natural cells and helps the body pick-kill them.
2.5. Memory Cell Formation
The final step is the formation of memory cells. Memory cells are nothing but B cells and T cells that differentiate during any immune response.
These cells “remember” the specific antigens encountered and thereby provide long-term immunity. If a person is exposed to the same pathogen more than once in his lifetime, these cells immediately recognize them and initiate a robust immune response.
3. Historical Background of Vaccines
Though our topic will mainly talk about the present trends and research in the field of vaccine development; it would be better if we have some idea about how we reached the current spot.
In the following few paragraphs, we will be learning about the journey of vaccines from the early 16th century up to now.
3.1 Early Development
The history of immunization (vaccination) dates back thousands of years. In ancient China and India, practitioners would expose individuals to small amounts of infectious material to induce immunity.
Later in the 16th century, Turkish physicians practised a method called “variolation“, where they would intentionally infect individuals with material from smallpox scabs to confer immunity.
The smallpox vaccine development is a significant milestone in vaccine history. In 1796, Jenner conducted an experiment where he inoculated an eight-year-old boy, James Phipps, with material from cowpox sores and then exposed him to smallpox.
Phipps remained unaffected, and this laid the foundation for the smallpox vaccine. The first smallpox vaccine prevented smallpox infection in 95% of those vaccinated.
3.2 Mid-era Development
In the 19th century, French scientist Louis Pasteur made a groundbreaking discovery. He developed the germ theory of disease. The thesis revolved around the idea that microorganisms were the main culprits behind infectious diseases.
Today we can develop vaccines for a huge spectrum of diseases. However, there was a time when it seemed like these diseases have no cure. Diphtheria, pertussis and tetanus (DPT) vaccines along with the polio vaccine by Jonas Salk and Albert Sabin have become go-to names on the market.
But let’s not forget the time when people thought that the best way to cure these diseases was to rub leeches on their skin!
3.3 Recent Development
Vaccination campaigns have been instrumental in significantly reducing if not completely eradicating several diseases worldwide.
The World Health Organization’s Expanded Program on Immunization (EPI) and initiatives like the Global Polio Eradication Initiative have made remarkable progress in controlling and eradicating diseases.
Vaccine development is still a baby sector with ongoing research. Currently, the studies are aimed at improving vaccine efficacy, safety, and most importantly accessibility.
The successful development of vaccines against COVID-19 showcases the dedication of scientists, collaboration among institutions, and the importance of vaccination in managing global health crises.
4. Techniques Involved
That brings us to the most enthralling part of the article. In the given section, we get to know about the various techniques involved in the process of building these medical marvels. Though the concepts are quite complex, it has been simplified for the convenience of the reader.
Inactivation can be considered one of the most commonly practised techniques for manufacturing vaccines today. Simply put, vaccines are created by inactivating the pathogen through various methods.
Some of the physical methods include heat killing or radiation killing, while chemical methods include extracting different parts or compounds from the pathogen with the help of chemical solutions or biocatalysts.
All this hard work results in the rendering of the pathogen’s physiological functions. In most cases, they are unable to cause disease while still retaining their immunogenic properties. Examples include the inactivated polio vaccine (IPV) and the inactivated influenza vaccine (IIV).
Another very in-use method is to create Attenuated vaccines. Unlike the inactivated type, here, we create vaccines weakening the pathogen. There are numerous ways to do so. But usually, scientists prefer serial passage or genetic modifications.
You might ask – Why not completely kill the microbe? The answer is simple. We need the cell’s mechanism so that it can still replicate within the body but with reduced virulence. This reduced virulence will give the patient’s body enough time to enact the attack.
These vaccines stimulate a robust immune response. Popular examples of attenuated vaccines are Rubella, Oral Polio Vaccine, and Measles.
4.3 Subunit Vaccines
Upon further research, scientists stumbled upon an even more clever idea for vaccine manufacturing. They were convinced that we don’t need the whole pathogen body to instigate the immune response.
Keeping this idea in mind, subunit vaccines were developed. These vaccines contain only specific antigens or parts of the pathogen, such as proteins or polysaccharides.
These vaccines are much safer because they do not contain the entire pathogen as in previous cases. Examples include the hepatitis B vaccine and the human papillomavirus (HPV) vaccine.
4.4 Toxoid Vaccines
Science is all about innovation in inventions. On successful trials of vaccines derived from pathogen parts, other convenient sources were searched. One of the vaccines thus developed was the – Toxoid vaccine.
Mainly, they are made from inactivated toxins produced by certain bacteria or sometimes non-infectious microbes as well. The vaccines fight against the toxins rather than the bacteria itself.
The tetanus vaccine is an example of a toxoid vaccine. Though this category of vaccines is still under research, we can prospect a positive future for them.
4.5 Conjugate Vaccines
Conjugate vaccines are a group of new-age vaccines. The process behind their making is complex. But for a newbie, they are created by attaching a polysaccharide antigen from a pathogen to a carrier protein.
In other words, we retrieve the virulent antigen from the pathogen and embed it into another protein that is not infectious by itself.
This technique enhances the immune response, particularly in young children, who may not respond well to the original antigens alone. Examples include the Haemophilus influenzae type b (Hib) vaccine and certain pneumococcal vaccines.
5. Recombinant DNA technology
Recombinant DNA technology is sort of omnipresent at present. Even vaccine development has not remained sacred to it. Before understanding its application in the process, we must understand what the term means.
The technique involves cutting foreign DNA and inserting it into the desired organism for required gene expression. In context to vaccine manufacturing, we insert genes encoding specific antigens of a pathogen into the host cells.
These vectors are usually bacteria or yeast as they produce large quantities of the antigen. This technique is used in vaccines like the hepatitis B vaccine and the human papillomavirus (HPV) vaccine.
5.1 Viral Vector Vaccines
Viral vector vaccines might seem intimidating and risky at first thought. Most first-time readers are surprised to know that something as infamous as a virus could also be used for providing immunity.
The mechanism is simple – we use a harmless virus such as an adenovirus or a modified vaccinia virus. The viruses act as a delivery system to introduce genes encoding antigens into the body.
These genes are then expressed and end up triggering an immune response. The COVID-19 vaccines developed by AstraZeneca and Johnson & Johnson utilize viral vector technology.
5.2 mRNA Vaccines
A mRNA is the first coding sequence of a protein. If we can manipulate this very sequence, we will be able to alter the gene expression as well. How is this done?
Well, the vaccines introduce a synthetic version of the messenger RNA (mRNA) that encodes the antigen of interest into the body’s cells. The cells are then interpreted by the body. Eventually, they produce the antigen, stimulating an immune response.
The Pfizer-BioNTech and Moderna COVID-19 vaccines are mRNA vaccines. This is the current most in-demand and actively researched genre of biotech.
5.3 DNA Vaccines
Some people try to connect RNA vaccines to DNA vaccines. But it is not quite accurate as they differ a lot, especially in their means of action. It involves the direct injection of a plasmid containing the gene encoding for the desired antigen of interest into the body’s cells.
The cells then produce the antigen in response to the detected antigen. Thus, initiating an immune response. DNA vaccines are being explored for various infectious diseases and cancers which will change how we perceive medicine today.
5.4 Protein Subunit Expression
This technique is a patchwork of all the above technologies that we read about. Essentially, it involves producing large quantities of specific proteins using recombinant DNA technology or cell cultures.
The purified proteins are then used as antigens by the recipient’s body. This is still a baby tech in comparison to the others. The main reasons are its lesser area of study and the unknown risks hinged to it. However, something as modernizing as protein subunit expression will not be overlooked for long.
6. Limitations in Vaccine Development
Vaccine development is a vital scientific endeavour revolutionising healthcare by preventing and controlling infectious diseases.
However, vaccine development is not without its limitations and challenges. Of course, it’s not all sunshine and rainbows! Vaccines don’t come with a money-back guarantee – you can’t just return them to the store if they don’t work!
This article examines some of the key obstacles encountered in vaccine development. These obstacles range from scientific complexities to manufacturing and distribution hurdles and social factors of vaccine hesitancy.
Despite these limitations, ongoing efforts and collaborations continue to drive progress in this field, leading to improved global health outcomes.
6.1 Scientific Complexities
One of the primary limitations of vaccine development arises from scientific complexities. Some pathogens, like the influenza virus or HIV, have intricate mechanisms of action or high mutation rates, making it challenging to develop effective vaccines.
The constant mutation of these pathogens necessitates vaccine formulation refinement and adaptation. Additionally, certain diseases, such as malaria and tuberculosis, have proven elusive in finding effective vaccines.
This is due to their complex interactions with the human immune system. For instance, HIV has been complicated to target, as it rapidly mutates and produces numerous variants, each requiring its unique vaccine formulation.
6.2 Resource Inventory
Developing a novel vaccine requires substantial time, resources, and rigorous testing. The process can span several years or even decades, involving extensive preclinical and clinical trials.
These trials are crucial for safety and efficacy but can contribute to lengthy development timelines. While safety is a paramount concern, rare adverse events or side effects can occur, raising concerns and potentially leading to setbacks. Striking a delicate balance between safety and effectiveness is crucial to vaccine development.
6.3 Vaccine Efficacy
Vaccine effectiveness can vary depending on several factors. Pathogen characteristics, individual immune responses, and vaccine formulations all play significant roles. Some vaccines confer lifelong immunity, while others require booster shots to maintain protection.
Specific populations, such as the elderly or immunocompromised individuals, may exhibit reduced immune responses, limiting vaccine effectiveness. Researchers continually strive to optimize vaccine design to maximize immune responses and improve overall efficacy.
6.4 Large-scale Production
Scaling up vaccine production and ensuring equitable distribution present significant challenges.
Vaccine manufacturing requires specialized facilities, expertise, and a robust supply chain. Sudden surges in demand, as witnessed during global pandemics, can strain production capacity, leading to shortages.
Distributing vaccines globally, particularly in remote or resource-limited areas, poses logistical hurdles that require innovative solutions and collaborations to ensure broad accessibility.
6.5 Vaccine Hesitancy
Another crucial limitation affecting vaccine development is vaccine hesitancy. Misinformation, mistrust, and cultural beliefs can contribute to hesitancy and scepticism surrounding vaccines.
Misconceptions about safety and efficacy, fueled by misinformation, can lead to lower vaccine uptake rates and compromise immunization efforts. Addressing vaccine hesitancy requires effective communication, public health education, and trust in healthcare systems.
7. What Do We Foresee?
The future of vaccine development is poised to bring significant advancements and transformative changes in the field. As a result of ongoing technological innovations and scientific breakthroughs, vaccine development is entering an exciting era.
Here, we explore some key trends and advancements that shape vaccine development’s future landscape.
7.1 Customizable Treatment
One of the most exciting prospects is the development of targeted and personalized vaccines. Scientists can now understand individual genetic and immunological profiles as a result of advances in genomics, immunology, and computational modelling.
With this knowledge, vaccines can be tailored to elicit precise immune responses, optimizing their effectiveness and minimizing side effects.
Personalized vaccines have the potential to revolutionize disease prevention and treatment, ushering in an era of highly customized healthcare interventions.
7.2 Curing the Incurable
Another groundbreaking development is the emergence of mRNA and vector-based vaccines. The success of mRNA-mediated COVID-19 vaccines showcases its power and versatility.
mRNA vaccines allow for rapid development and production, as the genetic instructions for producing viral antigens can be synthesized quickly This flexibility enables researchers to swiftly respond to emerging diseases and develop vaccines against various pathogens.
Ebola and Zika have both been treated with vector-based vaccines, which use harmless viruses to deliver genetic material and stimulate immune responses.
7.3 Vaccines with a Brain
A revolution is underway in vaccine development thanks to the use of computer modelling and artificial intelligence (AI). These tools can analyze vast amounts of data and simulate immune responses, aiding in vaccine efficacy prediction and identifying optimal vaccine targets.
Machine learning algorithms can accelerate vaccine candidate discovery by sifting through vast databases and identifying potential antigenic targets. This computational approach expedites vaccine development and enhances vaccine design and optimization efficiency.
8. In Addition
Furthermore, vaccine development encompasses versatile vaccine platforms capable of responding rapidly to emerging infectious diseases. The COVID-19 pandemic highlighted the need for adaptable vaccine technologies that can be swiftly deployed against novel pathogens.
Researchers are exploring modular vaccine platforms that can be easily modified to target different viral strains or even entirely new viruses. These platforms enable more efficient and timely responses to emerging outbreaks, reducing vaccine development and deployment time.
In conclusion, vaccine development holds immense promise, driven by advancements in targeted and personalized vaccines, mRNA and vector-based technologies, computational modelling, and adaptable vaccine platforms.
Through these innovations, better, safer, and tailored vaccines will be available to prevent, treat, and cure diseases.
And if all else fails, there’s always the tried and true method of Chicken Soup! As science and technology progress, the global community can look forward to a future where infectious diseases are better controlled. Additionally, the development of innovative and impactful vaccines enhances public health.