With the Covid 19 pandemic growing at an incredible rate to over 7 million cases, the race for the ideal vaccine our world longs for is the fastest endeavor the scientific community has ever seen.
What is a vaccine and why do we need it?
A vaccine is a product that stimulates a person’s immune system to produce immunity to a specific disease, protecting the person from that disease (CDC definition). Vaccines are made in a variety of forms- each one specifically tailored for its disease. Bill Gates says the pandemic will only end “when we have an almost perfect drug to treat COVID-19, or when almost every person on the planet has been vaccinated against coronavirus.” Unfortunately, he later states that the possibility of the solution of a drug does
not stand viable since none of the drug candidates are powerful enough. The Bill and Melinda Gates foundation have been very important supporters in developing a vaccine. Examples of vaccines from the past was the smallpox vaccine which was developed by Edward Jenner in 1796. Smallpox is now eradicated because of this vaccine. Most of us take vaccines during the flu season and many other vaccines throughout our childhood and later in life as well.
Herd immunity is an important healthcare term that has been used more frequently during these times because of the solution it presents when a vaccine is created. What this means is that when most of the community is immune to the disease, immunocompromised members, infants, and the elders will be protected. A way to picture herd immunity is as if the immune individuals are forming a circle around those who are vulnerable to the disease, therefore providing protection for all. Vaccines serve as important protection against potentially lethal diseases such as Covid 19 which is why if a Covid 19 vaccine is administered almost every human, the pandemic could slow down and eventually come to an end.
How does a vaccine work?
A vaccine’s purpose is to equip and train the body to fight the pathogen. When the pathogen first enters the body, it presents a molecule called an antigen to the body’s cells. The reaction to each antigen varies by disease since symptoms are not the same for every disease and the time period from exposure and symptoms are not consistent with all diseases either. As we have experienced Covid 19, cases can go asymptomatic for days and still transmit the disease which means that the coronavirus can enter the body undetected and grow in the lungs for up to 14 days. A vaccine sends in the pathogen in different forms (depending on the disease), so that the body will trigger an immune response and produce antibodies against the pathogen’s antigens. The antigen will not have the real effect and symptoms of the disease but will still prepare the body for when the harmful pathogen does enter so that the antibodies will already be ready. When a human’s immune system detects a pathogen’s antigens, the information on antigens are usually stored in specific cells called B lymphocytes which form memory cells to speed up antibody production when the pathogen is encountered again. Some vaccines do have minor side effects while others have none.
To go further into types of vaccines, a live, attenuated vaccine is a weaker form of the pathogen that gives life-long immunity, but could lead to a greater risk of acquiring the disease if administered to an immunocompromised patient. Another form is inactivated vaccines which are dead versions of the pathogen that the body can provide antigens against without the risk of the pathogen’s dangerous response. Although specific to certain diseases where the antigen is identifiable, the next type is the subunit/conjugate vaccine which is just the isolation of a specific protein or carbohydrate from the pathogen that will still cause the immune system to respond with a very low risk of developing the disease. The types that are specifically being experimented for Covid 19 vaccines are DNA vaccines that carry a few segments from the pathogens DNA to instruct the human cells to efficiently produce the antibodies. This was being experimented for influenza and herpes virus and if produced successfully for Covid 19, can be easily produced at a mass scale since it is on the cheaper side compared to the others. RNA vaccines are the alternate form of this which is also being researched for Covid 19 and function in a similar way. Recombinant vector vaccines carry DNA in a weakened pathogen and is just another form of teaching the body to combat the disease.
What are the phases for the development of a vaccine?
* Summarized from publichealthonline.gwu.edu
Exploratory phase: Research to identify the antigen that will prevent or treat the disease
Pre-clinical phase: In a private industry, researchers will test animals, tissues, or cells to evaluate the candidate vaccine’s effect on immunity.
Clinical Development Phase: An application for the vaccine is submitted to the Investigational New Drug (IND) and Food and Drug Administration (FDA) which summarizes and describes how the drug will be tested and created. A clinical trial will take place where the application will become approved. After it has been approved, the vaccine passes three more phases:
Phase I: Candidate vaccine is given to a group of 100 subjects and determines whether the vaccine is safe and observes effects on the test subjects.
Phase II: Candidate vaccine is administered to hundreds of test subjects to learn further into the details of the vaccine in terms of safety, dosage, and immunogenicity.
Phase III: Candidate vaccine may be administered to thousands to tens of thousands of subjects and continues to observe the vaccine.
Regulatory Review and Approval: The vaccine developer submits a Biologics License Application to the FDA.
Manufacturing: Drug manufacturers create vaccines to later become distributed.
Quality Control: The vaccine is still being tracked and examined to ensure its effectiveness and ability to provide immunity as anticipated.
The Covid 19 Vaccine Race “Leading Candidates”
Moderna Vaccine Trial
The Moderna vaccine was produced using biotechnology from messenger RNA molecules. It functions by carrying the codes for a specific spike protein on the RNA to combat Covid 19. Therefore, the vaccine should be able to transport the RNA to human body cells and the body should be able to produce antibodies to Covid 19. Although a new idea in the world of vaccines, the results of the vaccine, so far, have been quite successful. This vaccine has passed a test on mice which proved that the vaccine prevented the replication of coronaviruses in the respiratory tract (specifically the lungs). The vaccine was also administered on 8 healthy individuals, ages 18-55, and antibodies were produced in the test subjects that were able to fight the coronavirus in a lab-based setting. The Moderna vaccine was administered in a low, medium, and high dosage. The low and medium doses produced sufficient antibodies to strengthen immunity. However, the high dose caused fever, muscle pains, and headaches in three patients which reduced and disappeared after a day. The Moderna vaccine is currently undergoing its Phase II trial and hopefully holds promising results. Moderna has just finalized their Phase III of Clinical Development using the lowest dosage for maximum levels of production. The study will involve 30,000 participants in the United States and will begin in July. Participants will either receive the vaccine in a 50 mg or 100 mg dosage or receive a placebo to reduce bias and false, misleading conclusions. The Moderna vaccine has already created a significant impact on the stock market and continues to provide hope for the safety of all.
Oxford Vaccine Trial
The Oxford vaccine is another ongoing trial that has been successful so far. The vaccine itself is carried by a vector, adenovirus which is very commonly used for vaccines, so is reliable for the coronavirus. It was developed to carry the genetic code of the protein spikes found on the outer coating of the coronavirus. It triggers a strong reaction in the human immune system and should prepare humans for exposure to the coronavirus. The vaccine was first tested on monkeys and proved effective. Human testing began in late April in the UK with over a thousand healthy volunteers, initiating Phase II/III of vaccine development. Like any well-conducted study, there were two groups of volunteers, the control group and the group that is actually receiving the vaccine candidate. The control group is given a placebo which, again, reduces the chance of bias to achieve accurate results. If the results of the study are desirable, it is possible that the vaccine is administered in October. According to the University of Oxford website, Professor Andrew Pollard, head of the Oxford Vaccine Group, said: ‘The clinical studies are progressing very well and we are now initiating studies to evaluate how well the vaccine induces immune responses in older adults, and to test whether it can provide protection in the wider population. We are very grateful to the huge support of the trial volunteers in helping test whether this new vaccine could protect humans against the pandemic coronavirus.’ The Oxford Vaccine trial holds promising results and, in the best case scenario, could become an ideal front-runner for protection against Covid 19.
CanSino Vaccine Trial
The CanSino vaccine candidate was produced under China’s CanSino Biologics. It uses a adenoviral vector to deliver the gene for the spike protein of the coronavirus. The only two adenoviral vector vaccines that have been approved are China’s CanSino Ad5-based Ebola vaccine and a vaccine to prevent the spread of rabies in animals. The issue mentioned, like the previous vaccines, were the side effects. Symptoms that may have developed included fever, muscle pain, and fatigue, but most were moderate to mild, and not severe. The vaccine did produce the targeted levels of immunity in most test subjects and is moving on to Phase II of the process. According to CanSino, “The Ad5 vectored COVID-19 vaccine is tolerable and immunogenic at 28 days post-vaccination. Humoral responses against SARS-CoV-2 peaked at day 28 post-vaccination in healthy adults, and rapid specific T-cell responses were noted from day 14 post-vaccination. Our findings suggest that the Ad5 vectored COVID-19 vaccine warrants further investigation.” The results of the Phase II study will give us more information about the safety and effectiveness of the CanSino vaccine. Meanwhile, it is currently head to head with the other vaccines and has potential to ensure immunity for many.
There are many other vaccine candidates that are working on training human immune systems against the coronavirus and, eventually, we will find a suitable vaccine. This is the fastest moving race for the development of a vaccine that has ever been witnessed in history and it is not slowing down anytime soon. With the continued use of face coverings, social distancing, hand-washing, and safe hygienic measures, we can provide for our safety while scientists are hard at work creating a vaccine that could be the turning point for this pandemic.