Vaccines 101

In the midst of the COVID-19 pandemic

The COVID-19 pandemic has been an uncertain time for everyone, and the hopes for getting back to normal have largely rested on a vaccine being made. As time has passed and vaccines are getting closer to being manufactured, people have started to worry about the safety of the vaccine. I’m no expert in the fields of immunology or vaccine development, but I hope that this article can shed some light on what vaccines do, how they work, and how that might be applied to COVID-19.

Essentially, vaccines give your body a trial run that helps you build immunity to a disease before you catch it.

They do this by simulating a mini-illness inside your body that your body can learn how to fight against.

Your body has a natural defense mechanism when it encounters an illness. Similar to your red blood cells which carry oxygen to where it’s needed, you also have white blood cells that specialize in fighting infection. As explained by the CDC, these white blood cells can be thought about in 3 groups:

1. Macrophages

Macrophages are the vacuum cleaners of your body. They dispose of dead cells and germs. In their wake, they leave behind parts of the germs which are called antigens. Antigens are a foreign substance to the body and usually trigger an immune response.

2. B-lymphocytes

B-lymphocytes are your first line of defense. According to the CDC, “they produce antibodies that attack the antigens left behind by macrophages.”

3. T-lymphocytes

T-lymphocytes are another line of defense. They attack already-infected cells.

A vaccine intentionally introduces antigens into your body. The antigens trigger an immune response from your body, which it will then remember. Some vaccines can specifically trigger T-lymphocytes or B-lymphocytes, causing an immune response more personalized to the disease. When these antigens enter your body from the actual disease, your body already knows how to fight it and your symptoms are vastly reduced.

The issue with COVID-19, in particular, is that it causes an overwhelming immune response from your body. Your immune system goes out of control, and in the process of eradicating the virus, it also does damage to your beneficial cells. In order for your body to effectively beat back COVID-19, your immune system needs to learn to have a more targeted approach.

Different Types of Vaccines

Not all vaccines are the same. There are 4 main types of conventional vaccines:

1. Live-attenuated vaccines

These vaccines actually inject a little bit of a live disease into your body. But fear not! The live germs are weakened so that they do not pose a serious threat to your health. The most important benefit of the live-attenuated vaccine is that by fighting the live disease, your body gains immunity for very long periods of time, sometimes a lifetime. This is the kind of vaccine that you get for smallpox or measles. However, because they do inject live disease, they are not always a good option for people with reduced immune systems.

Live-attenuated vaccines are also probably not the best option for evolving diseases such as the flu (or COVID-19) because it does not make much sense to get a lifetime immunity to a virus that keeps on changing.

2. Inactivated vaccines (dead)

These vaccines inject a dead version of the germ that causes a disease rather than a live one. This is the type of vaccine you get for the flu. It does not have the risk that a live vaccine may pose, and it is easier to transport. However, it provides immunity for shorter periods of time, so you may have to have them administered annually or in a series of booster shots.

3. Subunit vaccines

A subunit vaccine doesn’t inject a whole germ, instead, it injects a specific part of the germ such as a protein or casing. These vaccines are beneficial because they target a specific part of the germ that might be doing you harm, and they are also safer for those with reduced immune responses. This is the type of vaccine you might get for HPV or shingles.

AstraZeneca, a British company that has been at the forefront of COVID-19 development, is producing a subunit vaccine. It has recently been revealed that their vaccine will continue the last stage of testing after they had paused the process.

4. Toxoid vaccines

These vaccines don’t actually inject a germ at all, they inject the infectious toxin that the germ would release. This allows your body to recognize and fight the toxin without having to fight the germ. Tetanus shots are an example of toxoid vaccines.

New Developments in Vaccines

The four types of vaccines that were listed above are your normal, day-to-day vaccines. And although they work, they do have some limitations, especially in fighting against evolving diseases like COVID-19. That’s why research has continued to push forward in the realm of vaccines, leading to some exciting new developments such as RNA vaccines.

Unlike the vaccines listed above, an RNA vaccine does not inject an antigen. It injects what is essentially a blueprint for your body to make the antigen. This blueprint is a molecule called mRNA. mRNA strands are what your body uses to make all your proteins. Because of this, mRNA is not toxic and RNA vaccines are safer to use.

RNA vaccines, believe it or not, are also easier (and cheaper) to make, as DNA templates are readily available in labs. They have also shown to be faster and more effective in creating immunity.

Even so, researchers have seen that some RNA vaccines elicit an unintended immune reaction which they are currently trying to control. It can also be difficult to deliver the mRNA molecule from the injection site to a cell, as it dissolves easily on the journey in between. Currently, researchers are combatting this by sending the mRNA packed inside another molecule, which can ensure its safe delivery.

One of the companies which has been working on a COVID-19 vaccine, Moderna, has been using RNA technology.

From the Lab to You

So what’s the process a vaccine has to go through in order to be released to the public?

First, researchers have to develop the vaccine. This means…. research! They have to decide what would go into the vaccine, how effective different options would be, and what specific molecules they are targeting.

Once researchers have settled what their vaccine will be like, it undergoes pre-clinical trials. The researchers will test the vaccine in animals, such as rats, before they begin trials in humans. If the vaccine is still considered safe after these tests, it moves to clinical trials in humans. Clinical trials have three stages. In stage 1, the vaccine is administered to about 100 people and tested for safety. Side effects are tracked. If all seems well, researchers proceed to stage 2. Here, the vaccine is administered to a couple of hundreds of people, where the participants are chosen to represent the public the vaccine would eventually be released to. Side effects are tracked again. Then, clinical trial 3 proceeds. In this stage, hundreds to thousands of people are administered the vaccine. It is important to remember that the number of participants in each trial listed above also includes the participants who are administered a placebo drug. As a result, the number of people who actually receive the drug is lower than the numbers above.

The FDA carefully oversees these trials to make sure they meet high-quality standards. If the vaccine makes it through all three clinical trials, and the results show that it is safe for the general public, the FDA will approve the vaccine and allow it to go into the manufacturing stage.

This is the same process that a COVID-19 vaccine will have to go through, and sometimes, it can take years. This is why some people are worried that by trying to speed up the process for COVID-19, the vaccine will not be as carefully tested. It is possible that a fast testing process will not catch certain side effects that may only reveal themselves after a longer period of time, although this stands true for many medications.

Your Choice

Vaccines are important not only because they keep you safe, but also because they keep your family and your community safe. If more people are vaccinated, when a cold or flu is going around, fewer people will get sick. This is important because in certain cases, there are people in a community that may not be able to get vaccinated. Living in a vaccinated community will keep them safe as well.

I hope that this article has broadened your knowledge of how vaccines work and what kinds of vaccines are out there. There are always going to be pros and cons when a new medication or vaccine is released. Every person should think about their own conditions and what risks they are able and willing to take. I encourage you to do your own research into the ongoing coronavirus vaccines, and make your own decisions about the vaccine when it does arrive.

Stay safe!

Citations

Kirby, Tony. “Development of Potential COVID-19 Vaccines Continues to Accelerate.” National Institutes of Health, Elsevier Ltd., 3 July 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7333995/.

“Moderna’s Work on a COVID-19 Vaccine Candidate.” Moderna, Inc., 28 July 1970, www.modernatx.com/modernas-work-potential-vaccine-against-covid-19.

“RNA Vaccines: an Introduction.” PHG Foundation, www.phgfoundation.org/briefing/rna-vaccines.

Steckelberg, Aaron, et al. “These Are the Top Coronavirus Vaccines to Watch.” The Washington Post, WP Company, 19 Oct. 2020, www.washingtonpost.com/graphics/2020/health/covid-vaccine-update-coronavirus/.

“Understanding How Vaccines Work.” CDC, July 2018, www.cdc.gov/vaccines/hcp/conversations/downloads/vacsafe-understand-color-office.pdf?fbclid=IwAR1n8hXXk_ZJtbiu7yfGW9sUiIiIsK68HVgASBrFQreMogRqIcyP8bVtBFY.

“Vaccine Types.” Vaccines, www.vaccines.gov/basics/types.

Photo Citation

Plieth, Jacob. “US Panel Puts the Spotlight on Pivotal Covid Vaccine Readouts.” Evaluate.com, 23 Oct. 2020, www.evaluate.com/vantage/articles/news/policy-and-regulation/us-panel-puts-spotlight-pivotal-covid-vaccine-readouts.