How do Vaccines Work? What are they supposed to do?

Okay, so we’ve all been hearing things like “Go and get vaccinated” and “Talk it over with your doctor, and decide if it’s right for you”, those are the two main sides of the argument, while other people talk about things like you shouldn’t take them because they will make you magnetic (not true) or have some other reason not to take them. Some say they do work, others say they don’t work, and there’s a lot of information flying back and forth so where do we start?

Well, one good place to start is to go through what the vaccine’s supposed to be doing in the first place, then we will have a gauge to indicate if it’s working (meeting that goal) or not.

So, what are vaccines supposed to do? Simple. They introduce an inert form of a virus to your immune system, then they go away.

No force fields to prevent you from catching the virus, no little army of robots that kill the virus with laser eyesight, and nothing very fancy at all. The vaccine simply tells your immune system that this threat is out there and that it should prepare.

Okay, wow, this was a short article. But now that I have you here, let’s talk about something else — why you'd want to do that in the first place.

How does the Immune System work? in relation to viruses and vaccines.

The human immune system is one of the most complex parts of our bodies, so let’s narrow the conversation a bit. Let’s start by separating it into two categories, the innate immune system, and the adaptive immune system.

The innate immune system is sort of “always on”, it reacts right away, and in generic ways to a variety of threats. Things like pain signals, inflammation, and even running a fever are all tools in the innate immune system. It’s very useful for immediate threats like if you get a cut, the innate immune system jumps into action right away and tells you that it hurts (so you don’t make the problem worse), it causes inflammation (which allows you to heal faster) and it starts to create a scab over the wound (to close the cap so that bacteria and other things can’t enter your body anymore).

For viruses though, we’ll focus more on the other category, the adaptive immune system. This is where our immune system will customize its response to a specific threat, such as a specific virus. When we use a vaccine, there are two main responses we are trying to trigger from our adaptive immune system.

The first reaction is we want our immune system to learn about this new threat, and come up with an antibody specifically tailored to combat it. It can sometimes take a few doses to be certain we’ve invoked this response, which is why for many types of vaccines we’re not considered “fully vaccinated” until 2 to 3 shots. The really cool thing is that once our immune system learns how to make those antibodies, it NEVER forgets. It’s like an endless database of counter-tactics against all the different types of viruses you’ve encountered in your lifetime. Or, if you are the CDC, you may word it like this ‘with all types of vaccines, the body is left with a supply of “memory” T-lymphocytes as well as B-lymphocytes that will remember how to fight that virus in the future.’

The second reaction we’re going for is for your immune system to actually make a “batch” of antibodies. It can take up to two weeks to make a full “batch”, especially if we’re older — because like the rest of our body the immune system slows down as we age. The important thing to remember here is that those antibodies don’t last forever, and your immune system won’t continually keep making more — it only makes them when it detects that it’s needed. It’s generally accepted that you can maintain a decent level of antibodies for about six months.

When we’ve done these things, we’re considered “immunized” against that virus. This doesn’t mean that we are nigh-invulnerable like the way we use the term “immune” in superhero comic books, it just means that we’ve provided what information we could to our immune system, and now it’s up to it to keep us protected.

Okay, so if our immune system never forgets how to make antibodies, then why do we only need to get vaccinated for some viruses, but need a “booster” for other viruses? This has to do with a virus’s incubation period.

A virus’s incubation period is the time that the virus enters our system (maybe we breathed it in, accidentally rubbed it in our eye after touching a contaminated surface, it got in through a cut, etc) and it replicates to the point of us really noticing (showing symptoms or becoming contagious). This is important to think about in terms of vaccines and viruses because we “catch” viruses all the time, but if it’s dealt with before we notice then we don’t know that we have. This leads to the phrase “catch a virus” having two different uses in conversation, one is that a virus entered your system, and the second is when we noticed. In our conversation, we’re going to use the first meaning, and according to that vaccines can’t keep you from catching the virus. However, your immune system can prevent you from noticing.

Suppose a virus has a long incubation period, such as mumps, polio, or chickenpox. In that case, that usually gives your immune system the time it needs to create that “batch” of antibodies that can neutralize the threat before you ever notice. If a virus has a short incubation period, such as influenza, a cold, or COVID-19 then your immune system has much less time to react, and the virus will get a lead in the battle.

When viruses have a shorter incubation period, and we think they will be widespread, boosters may be recommended. A booster is just the vaccine being introduced to your immune system again, but the idea is that since you already have the blueprint for the antibodies the goal now is simply that second reaction of making a fresh “batch” that should last you another six months.

Vaccines, boosters, and viral infections can also stimulate the creation of T-cells, which are not as picky (nor as specialized) as antibodies are and can provide additional protection even after the antibodies have died off. Unlike antibodies whose sole mission is to destroy the threat they were tailored for, T-cells can provide a variety of functions to help protect us.

Recommendations for boosters are often made to provide updated intelligence on variants. When viruses replicate then they can make an error, this is called a mutation. Most mutations are not beneficial to the virus, but every now and then one can be. So the more a virus has the chance to replicate, the higher the chance of it mutating in a way that helps its survival. When it comes to our immune system though, after a virus mutates it means our database of antibody blueprints gets a little out of date. As of the time of this writing, we’re seeing that the Omicron variant of COVID-19 is spreading almost as fast among the population of vaccinated people as unvaccinated people. Is this a sign that vaccines don’t “work”? No, it’s a sign that the intelligence we provide to our immune system needs to be updated, because there are at least 37 changes that we’re not telling it about.

What about “natural immunity”? Is it any different? As far as your immune system reaction, the answer is no. Your immune system will respond by making the blueprints for antibodies, then creating those antibodies if you get vaccinated or “catch” the virus. The difference is that with the vaccine the “threat” is just a warning, not an actual threat. Think of it like a fire alarm drill. When the fire alarm is pulled, that alarm alerts everyone that there is a fire in the building. So, we are supposed to react as if there really is a fire. But if it’s a drill, we can safely walk back into the building afterward.

Vaccines can have other benefits to naturally catching a virus too, besides not getting as sick, you can vaccinate for multiple variants at once. When we get our influenza shot each year, it rarely just introduces our immune system to a single strain of influenza. Rather it’s a cocktail of the various strains the experts think will be widespread that flu season. If you catch the flu, on the other hand, your body will only make the antibodies for that one specific strain, leaving you just about as vulnerable to the other variants as if you had not gotten “immunized” at all.

And finally, what about the side effects? We already covered that vaccines don’t make people magnetic, but if the vaccines are simply providing intelligence to our immune system does that mean that they don’t have any side effects at all? No, you can most certainly have side effects, but in essence, those side effects are due to your immune system responding in a way we don’t want it to. Since the entire point of vaccines is to provoke our immune system to respond, there’s always the possibility that it will respond in a way we don’t want it to.

Remember at the start we said that inflammation was a tool of our innate immune system. When the body senses a threat, it can respond with inflammation. This is why the site where we receive an injection can become sore, and inflammation in different parts of our body can have different names. Myocarditis is a side-effect of vaccines that gets a lot of press because it sounds very scary, but when we dive down into what it actually is — it is inflammation. So, an immune response.

When the area of your body that becomes inflamed is your heart, we call it myocarditis, and yes it can cause problems because we don’t want our hearts to get inflamed. However, if our immune system responds to a vaccine with inflammation then it’s going to respond to the virus the vaccine is based on in a similar way. The difference is that the vaccine leaves your system, where the virus does everything it can to stick around. In general, if someone has myocarditis as a reaction to a vaccine, then they would have had a much more severe reaction to the virus itself. The doctors who have studied this to determine the pros and cons of vaccinating have determined that the benefits still outweigh the risks, but if you have a family history of heart issues then this is something you should discuss with your doctor.

Anyway, I hope I helped some of you gain a better understanding of how vaccines work, please follow some of the links in the section below to learn even more, such as where viruses come from, or more details about what’s involved with the innate and adaptive parts of our immune systems.

Thanks for reading!

Further learning:

The CDC’s explanation as to how vaccines work: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html

Johns Hopkins Medicine explains the basic parts of the Immune System: https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-immune-system

Philipp Dettmer talks about his awesome Youtube Channel and book Immune, which are great resources for learning about the Immune System: https://www.newscientist.com/article/0-kurzgesagt-ceo-philipp-dettmer-everything-can-be-made-into-a-story/

This is the Reference list for Philipp Dettmer’s book “Immune: a Journey into the Mysterious System that Keeps You Alive”: https://kurzgesagt.org/immune-book-sources/

If the Kurzgesagt youtube channel isn’t enough, Ted-Ed also made a video quickly explaining the Immune System: https://www.youtube.com/watch?v=PSRJfaAYkW4

Or, if you prefer a Slideshow over a video, WebMD has you covered- https://www.webmd.com/cold-and-flu/ss/slideshow-immune-system

More about T-Cells, and how they relate to fighting off Omicron -https://www.nature.com/articles/d41586-022-00063-0

Finally, if you want to know where viruses came from in the first place… PBS Eons has some clues: https://www.pbslearningmedia.org/resource/viruses-come-eons/viruses-come-eons/