|Year : 2021 | Volume
| Issue : 1 | Page : 1-4
The journey of COVID-19 vaccine: From despair to hope
Dte Gen Dental Services, New Delhi, India
|Date of Submission||23-Jan-2021|
|Date of Acceptance||28-Jan-2021|
|Date of Web Publication||09-Mar-2021|
N K Sahoo
Dte General Dental Services, “L” Block Army HQ, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sahoo N K. The journey of COVID-19 vaccine: From despair to hope. J Dent Def Sect. 2021;15:1-4
Vaccines save millions of lives each year. Vaccines work by training and preparing the body's natural defenses – the immune system to recognize and ward off the viruses and bacteria they are targeted toward. Any subsequent illness by the causative organism is rendered noninfective as the immune system of the body is immediately ready to destroy them.
The tectonic event of the present millennium came in the form of a submicron particle which took the world by surprise, and before the humankind could react in a befitting manner, the COVID-19 virus had shaken the very basis of the human species and in the process permanently altering our perspective toward almost everything be it personal hygiene, work ethics, social interaction, or travel.
In the initial phase, it was not dealt with the alacrity it deserved, and by the time heed was paid to the alarming bells ringing for quite some time, the virus was infecting people across all ethnic or geopolitical boundaries at breakneck speed. While the world had faced similar outbreaks in the past, COVID-19 numbers were simply mind boggling and the medical services all over the globe were overstretched in no time.
With the dental healthcare professionals at the pyramid of high risk of contracting the new virus, the entire profession waited with baited breath for some good news in the form of proven long-term protection which no pharmacological agent other than a vaccine offers.
To Prevent or to Cure?
It is common knowledge that the common cold or flu is a viral infection that is self-limiting and, in majority of the cases, subsides without any major complications and that is what has been our understanding for ages. In the initial phase of the COVID-19 outbreak, this very ideology kept the healthcare sector in a false sense of security, and by the time magnitude of the potential risk dawned on everyone, the fatality rate due to COVID-19–related complications had peaked.
Although many pharmacological agents in the form of new medicines such as favipiravir and, remdesivir were used to counter the insurmountable COVID-19 infections, no medication was proven to be effective in every case, and hence, the need for an early availability of a vaccine was felt like never before.
There are currently more than 50 COVID-19 vaccine candidates in trials. The WHO is working in collaboration with scientists, business, and global health organizations to speed up the pandemic response. When a safe and effective vaccine is found, COVAX (led by the WHO, Global Alliance for Vaccination and Immunization, and Coalition for Epidemic Preparedness Innovations) will facilitate the equitable access and distribution of these vaccines to protect people in all countries. People most at risk will be prioritized. While work toward rolling out a safe and effective vaccine moves at a hectic pace, one must continue the essential public health actions to suppress transmission and reduce mortality.
Revisiting the Arsenal
Vaccination is a simple, safe, and effective way of protecting people against harmful diseases, before they come into contact with them. It uses our body's natural defenses to build resistance to specific infections and makes the immune system stronger.
Vaccines train the immune system to create antibodies, just as it does when it is exposed to a disease. However, because vaccines contain only killed or weakened forms of pathogens such as viruses or bacteria, they do not cause the disease or put you at risk of its complications.
The vaccines can be divided into four different types:
- Live-attenuated vaccines
- Inactivated vaccines
- Subunit, recombinant, polysaccharide, and conjugate vaccines
- Toxoid vaccines.
Live vaccines use a weakened (or attenuated) form of the disease-causing pathogen.
Because these vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response. Just 1 or 2 doses of most live vaccines can give you a lifetime of protection against the pathogen.
However, live vaccines also have some limitations, viz.,
- Because they contain a small amount of the weakened live virus, some people should talk to their healthcare provider before receiving them, such as people with weakened immune systems, people with long-term health issues, or people who have undergone an organ transplant
- They need to be kept constantly at near zero temperatures, so they need proper transportation safety measures also. That also implies that they cannot be used in countries with limited access to refrigerators.
Live vaccines are used to protect against:
- Measles, mumps, rubella (combined vaccine)
- Yellow fever.
Inactivated vaccines use the inactivated version of the disease-causing pathogen. Inactivated vaccines usually do not provide immunity (protection) that is as strong as live vaccines and hence the need for several doses over time (booster shots) to get ongoing immunity against diseases.
Inactivated vaccines are used to protect against:
- Hepatitis A
Subunit, recombinant, polysaccharide, and conjugate vaccines
Subunit, recombinant, polysaccharide, and conjugate vaccines use specific pieces of the pathogenic agent such as its protein, sugar, or capsid. Because these vaccines use only specific pieces of the microorganism, they give a very strong immune response that is targeted to key parts of the pathogen. They can also be used on almost everyone who needs them, including people with weakened immune systems and long-term health problems.
The only limitation of these vaccines is that you may need booster shots to get ongoing protection against diseases.
These vaccines are used to protect against:
- Haemophilus influenzae type b disease
- Hepatitis B
- Human papillomavirus
- Whooping cough (part of the DTaP combined vaccine)
- Pneumococcal disease
- Meningococcal disease
Toxoid vaccines use a toxin (harmful product) made by the causative pathogen that causes a disease. They create immunity to the parts of the pathogen that are pathogenic instead of the germ itself. That means the immune response is targeted to the toxin instead of the whole pathogenic microorganism.
Some of the toxoid vaccines that are commonly used include:
- The future vaccines include:
- DNA vaccines – which are easy and inexpensive to make and provide strong, long-term immunity
- Recombinant vector vaccines (platform-based vaccines) act like a natural infection, so they are especially effective at programming the immune system in fighting the pathogens.
Vaccines reduce risk of getting a disease by working with the body's natural defenses to build protection. Postvaccination, the immune system:
- Recognizes the invading germ, such as the virus or bacteria
- Produces antibodies
- Remembers the disease and how to fight it. If exposed to the same pathogen in future, immune system can quickly identify and destroy it before one fell ill.
The vaccine is therefore a safe and clever way to activate an immune response in the body, without causing illness.
Our immune systems are designed to remember. Once exposed to one or more doses of a vaccine, we typically remain protected against a disease for years, decades, or even a lifetime. This is what makes vaccines so effective. Rather than treating a disease after it occurs, vaccines prevent us in the first instance from getting sick.
Glimmer of Hope
The worldwide focused effort to develop a safe and effective COVID-19 vaccine on a war footing is beginning to bear fruit. A handful of vaccines now have been authorized around the globe while many more remain in development.
Currently, there are three main types of COVID-19 vaccines that are or soon will be available for use. It would be pertinent to know how each type of vaccine prompts our body to recognize and protect us from the virus that causes COVID-19.
- mRNA vaccines contain material from the virus that causes COVID-19 that gives our cell instructions for how to make a protein that is unique to the virus. After our cells make copies of the protein, they destroy the genetic material from the vaccine. Our bodies recognize that the protein should not be there and build T-lymphocytes and B-lymphocytes that will remember how to fight the virus that causes COVID-19 if we are infected in the future
- Protein subunit vaccines include harmless pieces (proteins) of the virus that causes COVID-19, instead of the entire germ. Once vaccinated, our immune system recognizes that the proteins do not belong in the body and begins making T-lymphocytes and antibodies. If we are ever infected in the future, memory cells will recognize and fight the virus
- Vector vaccines contain a weakened version of a live virus, a different virus than the one that causes COVID-19 that has genetic material from the virus that causes COVID-19 inserted in it (this is called a viral vector). Once the viral vector is inside our cells, the genetic material gives cell instructions to make a protein that is unique to the virus that causes COVID-19. Using these instructions, our cells make copies of the protein. This prompts our bodies to build T-lymphocytes and B-lymphocytes that will remember how to fight that virus if we are infected in the future.
How COVID-19 mRNA Vaccines Work
COVID-19 mRNA vaccines give instructions to our cells to make a harmless fragment of protein known as the “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19.
Once the COVID-19 mRNA vaccine is administered, instructions (mRNA) are inside the immune cells, and the cells use them to make the protein fragment. After the protein fragment is made, the cell breaks down the instructions and gets rid of them.
Next, the cell displays the protein fragment on its surface. Our immune systems recognize that the protein does not belong there and begin building an immune response and making antibodies, like what happens in natural infection against COVID-19.
At the end of the process, our bodies have learned how to protect against future infection. The benefit of mRNA vaccines, like all vaccines, is that those vaccinated gain this protection without ever having to risk the serious consequences of getting sick with COVID-19.
Harbingers of Hope
Taking stock of the grim situation, the global pioneers in vaccine production took an early initiative while the federal governments all over the world pulled out all stops and the necessary regulations and approvals were fast tracked to ensure early vaccine availability.
Even though the Sputnik V was the earliest vaccine to be released, its efficacy was not proven, and hence, its wide acceptance remained elusive. Following vaccines are ahead in the race to realization of the much awaited vaccine launch globally:
- Pfizer-BioNTech vaccine is 95% effective at preventing laboratory-confirmed COVID-19 illness in people without evidence of previous infection
- Moderna vaccine was 94.1% effective at prevention of laboratory-confirmed COVID-19 illness in people who received two doses who had no evidence of being previously infected.
Both these vaccines appeared to have high effectiveness in clinical trials (efficacy) among people of diverse age, sex, race, and ethnicity categories and among persons with underlying medical conditions.
The Indian Vaccine Story
Indian Government was at the forefront of making rapid strides in the development of the COVID-19 vaccine much in sync with the Make in India initiative by the pharmaceutical companies, and as our present issue goes to press, following vaccines have been cleared for use by the statutory body of our country and vaccination is just a few days away.
Covaxin (Bharat Biotech/Indian Council of Medical Research)
Covaxin is India's first indigenous vaccine. The Phase I human clinical trials of the vaccine have been completed, and on June 29, Bharat Biotech had announced that it had successfully developed “Covaxin” in collaboration with the Indian Council of Medical Research and National Institute of Virology.
The vaccine received DCGI approval for Phase I and II Human Clinical Trials and the trials commenced across India from July 2020.
After successful completion of the interim analysis from the Phase I and II clinical trials of COVAXIN™, Bharat Biotech received the Drugs Controller General of India (DCGI) approval for Phase III clinical trials in 26,000 participants in over 25 centers across India.
The DCGI granted permission to Bharat Biotech for Phase I and II human clinical trials after it had submitted results generated from preclinical studies, demonstrating safety and immune response.
The vaccine has been approved for use and shall shortly be administered on a large scale.
ZyCoV-D (Zydus Cadila)
Drug firm Zydus Cadila reports said that the doses of the vaccine administered to healthy volunteers in Phase I clinical trial, which began on July 15, 2020, have been well tolerated.
The company closely monitored all the subjects in Phase I clinical trial in a clinical pharmacological unit for 24 h postdosing for safety and 7 days thereafter, and the vaccine was found to be very safe.
In November, Zydus had received approval from domestic authorities to start human trials for its COVID-19 vaccine contender – the second Indian pharmaceutical firm to get such nod amid a surge in novel coronavirus infections worldwide.
ChAdOx1/Covishield (Oxford University-Astra Zenecain partnership with Serum Institute of India
The Serum Institute of India has been permitted for conducting Phase II and III human clinical trials of the third vaccine candidate developed by the Oxford University. The Pune-based institute has partnered with AstraZeneca for manufacturing the vaccine.
The vaccine is being jointly developed by the British-Swedish company AstraZeneca, and the University of Oxford is based on a chimpanzee adenovirus called ChAdOx1.
A study on monkeys found that the vaccine provided them protection. The Phase I/II trial of the vaccines revealed that it was safe, causing no severe side effects. It raised antibodies against the coronavirus as well as other immune defenses. The vaccine passed muster in Phase II/III trials in England and India, as well as in Phase III trials in Brazil and South Africa.
The Covishield vaccine has received the approval and is being transported across the length and breadth of the country for kick start of a massive vaccination program soon.
As the global humankind across all continents eagerly awaits and gears up to receive COVID-19 vaccine, the rapid development of these vaccines has been an unprecedented phenomenon and an unparalleled example of human resilience. This aspect of the vaccine development is truly an inspiring saga of human endurance against all odds, which shall keep us motivated for a long time in foreseeable future to face similar challenges with a heightened sense of self belief and confidence.