Your Immune System As A Soccer Team: Understanding Key Players and the COVID-19 Vaccine
This is probably the first time you’ve ever looked forward to getting a vaccine. Coronavirus antibodies feel like a much greater reward than the stickers and Oreos I got after my flu shot when I was a kid. With the FDA’s emergency authorization of the Pfizer vaccine, the United States is preparing to vaccinate its population against COVID-19. Millions of doses are being shipped across the country, a product of 11 months of incredible work from Pfizer and BioNTech. Moderna also submitted a vaccine for FDA EUA, and it’s likely there will be distribution of that vaccine later this month.
A lot of people are worried that the speed of vaccine development has involved cutting corners. While it’s true that this is the quickest that we’ve ever made a vaccine (the previous record being four years), that reflects the urgent need for a coronavirus vaccine (and scientific advancement), rather than compromised safety. Essentially, a lot of phases of development that usually occur sequentially were run in parallel, but all of the phases were still run. Further, serious vaccine side-effects (i.e., autoimmune disease) usually emerge in the first few months, and those were not observed in the Pfizer nor Moderna trials. If you’re looking for more answers to FAQs on the speed of development and efficacy of the vaccine, check out this interview with Dr. Saad Omer, who leads a World Health Organization COVID-19 vaccine safety group.
As digitally literate young people, it’s our job to stop the spread of misinformation. But first, you need all your information. Here’s the basic info on how vaccines work and the mechanism involved with the COVID-19 vaccine.
What’s in a vaccine?
Making vaccines is a really tricky task because you want to induce an immune response that is close to the real disease without actually causing the real disease. Basically, vaccines contain either live bacteria or virus, dead bacteria or virus, full cells, or little bits of bacteria or virus. This is the antigen, the foreign substance that the immune system has to fight off. For example, our chicken pox vaccine contains weakened chicken pox virus, while our pneumococcal disease vaccine contains a bunch of polysaccharides (combinations of sugar molecules).
An easy way to understand vaccine function is to imagine your immune system as a soccer team and the vaccine is holding a scrimmage. You want to practice exactly what you’ll do on the actual game day. You want the right players in the right positions, but you also don’t want to completely exhaust your team or injure any of your star players. You especially don’t want tempers to run high and for your players to start fighting each other (what happens when a vaccine leads to autoimmune disease). You wouldn’t want to choose the U.S. Women’s National Soccer Team to scrimmage against your immune system; the Megan Rapinoe of antigens would demolish you. But you also wouldn’t play against a kindergarten soccer team, where you could stand there and do almost nothing and still win. That’s why it’s super important to choose the right antigen.
In the COVID-19 vaccine, the antigen is messenger RNA. While this is the first licensed vaccine to use mRNA, the uses of mRNA in vaccinology have been studied for decades (which is part of the reason that this vaccine could be developed so fast). Basically, the mRNA is like a playbook that instructs your cells to build a protein called “spike protein.” The spike protein is the same protein that COVID-19 uses for entering cells in an actual infection (I’m sure you’ve seen a drawing of coronavirus in the past year; the spike protein is the spiky part). Once cells build their own COVID-19 spike protein, they start putting spikes on their surface. The immune system can recognize that the spikes are not supposed to be there and start designing a response against it. Now, if you were infected with actual COVID-19 after being vaccinated, your immune system would see the spikes on the virus and deploy this pre-designed strategy against it.
mRNA vaccines are great for a few reasons. For one, this isn’t a live virus, so there’s little risk of inducing disease; the vaccine can’t give you COVID-19. Secondly, it’s way quicker to make synthetic mRNA than it is to grow entire viruses like we do for other vaccines. Once you inject the mRNA, the human body can do all of the work! The COVID-19 vaccine is a huge win for mRNA vaccinology in general and could lead to further breakthroughs in developing vaccines for HIV and cancer.
What’s the immune response?
So, maybe you’ve tossed around the word “antibodies” without really knowing what it means. That is totally okay! But the immune system is actually one of the coolest parts of our entire body, so it’s worth learning about.
Our immune system is made up of two different branches: the innate immune system and the adaptive immune system. When we talk about vaccines, we mostly are concerned with the adaptive immune system, because that’s the one that can make a specific response to a pathogen and remember the response. The innate immune system is working hard 24/7; it’s powerful and fast, but it’s designed to communicate with and depend on the adaptive immune system.
When we talk about the adaptive immune system, we’re mostly talking about B and T cells. These are the co-captains of your immune system soccer team, circulating throughout your body to find potential invaders and start mounting a response. T cells are made in your thymus, and there are a few different kinds. Once they recognize an invader, some T cells instruct the rest of the immune system on what to do, some kill infected cells to prevent the spread of disease, and some tone down the immune response so it doesn’t overreact and do more harm than good.
B cells also circulate and look for invaders to bind. Imagine B cells as having little tiny lobster claws and every B cell has a different kind of lobster claw. If one finds an invader that it can pinch onto, it becomes a lobster claw factory, makes thousands of its tiny lobster claws, and shoots them off into the bloodstream. The B cell also divides to make more B cells, which means there’s now tons of lobster claw factories making tons of tiny lobster claws. These tiny lobster claws are antibodies.
When antibodies bind to viruses, they can block them from entering cells, clump them together for another immune system cell to destroy them, or tag them for an innate immune cell to eat them. These antibodies can stay circulating in your blood for a long time and B cells remember which antibodies fight off specific viruses. It’s this memory ability of the immune system that confers immunity to certain pathogens. When we talk about antibody titers for COVID-19, we’re talking about the level of lobster claws in the blood. The course of disease (how sick you get) likely determines how long your immune system will retain antibodies for COVID-19. In terms of vaccines, we try to maximize the level of antibodies induced by the vaccine. With the COVID-19 vaccine, B cells would be instructed to make antibodies against the spike protein. This way, if you actually got infected with coronavirus, the lobster claws would tear it apart.
I could write forever about how cool the immune system is, but for now I will leave you with this image of the lobster clawed soccer team inside of your body. Vaccinating the world is the only way to fully stop the spread of disease, so it’s really important to learn more about vaccines and the ways they are being distributed.
on that note, here’s your call to action:
- Read more about the COVID-19 response. I like this ongoing article from Nature that summarizes key research findings. This vaccine tracker from The New York Times is pretty comprehensive as well.
- Misinformation is a public health crisis. Actively stop the spread! If your parents or friends or elderly relatives are sharing anti-vaccine rhetoric, take the time to educate them in a kind and helpful way.
- Read about Dr. Kizzmekia Corbett, the Black woman scientist that Dr. Fauci recognized as being instrumental to COVID-19 vaccine development.
- Read more about the efforts to distribute a COVID-19 vaccine to all countries.
–Sophia Marusic, Content Creator
