How Do Vaccines Work?
Learn how the immune system works and how vaccines use immunity to prevent bad illnesses.
Today’s topic will be vaccines and how they work. With all of the controversy surrounding vaccines, I thought that if I am going to make a case for them, I would do little good by giving the standard finger-wagging lecture. People need first to understand infection and immunity before they will accept my claim that immunizations are invaluable.
What is Immunity?
As I said in my antibiotic podcast, the immune system is the police force of your body. The white blood cells are the officers on the beat, wandering around your bloodstream looking for germs that want to live in your body and cause trouble. If they find a trouble-maker, they promptly identify it and destroy it.
The two main trouble-causing “bad guys” are bacteria and viruses. Both have their tricks to get past your defenses, and both can cause mild or severe infections. But of the two, viruses are the trickier ones, so I’ll focus on them. The theory is the same for either kind of infection.
What Are Viruses?
A virus is a little protein box containing DNA or other genetic material that takes over cells in your body. They are like bad guys who sneak into a country and take over factories so they can send off propaganda to recruit more bad guys to join their cause. The viruses get inside the cells, which are little factories, and make more viruses that can take over other cells to make even more viruses, and so on. The end result is a whole lot of viruses floating around.
How Do Viruses Spread?
But for a virus to be successful, it can’t just stay in one person; it must go to others. It does this in many ways, most commonly by inducing you to either get a snotty nose and sneeze particles into the air, or have diarrhea. The ability of a virus to go from one person to another is the same thing as its contagiousness.
How Does the Immune System Work?
But some people get sick when exposed to a virus, whereas others do not. What’s the difference? The difference is the state of the immune system. If in the past you have been exposed to a virus (or even one that is closely related), your body will recognize it and attempt to fight it off. If, however, you have never been exposed to that virus, it will take much longer for your body to recognize it as hostile and mount a defense. The people who haven’t been previously exposed to the virus are more likely to get infected by it, and the illness is more likely to be severe.
Polio and Other Viruses
To illustrate my point, let’s talk about polio--a virus that attacks the nervous system, leading to weakened muscles, paralysis, and possibly even death. Before the polio vaccine was invented, every year in the late summer people would fear that they or their children would contract this virus. But what most people don’t know is that polio hadn’t always been so deadly.
Prior to sewers and sanitation, people were constantly exposed to germs, including polio. That exposure was constant and low-grade, and so everyone had a degree of immunity to it. The advent of sanitation, however, stopped this low-grade exposure, leading to a generation of people without any immunity to the virus. That made the population ripe for epidemics like the ones that happened during the polio outbreaks.
How Do Vaccines Work?
So what’s the solution? Get rid of sewers and sanitation? Do we let people get exposed to deadly diseases so they can build immunity?
The best solution is to expose people to the infectious agent without getting them sick. That is exactly what vaccines are. I tell children (who absolutely hate getting shots), that the reason we give them a shot is to show their body what the bad germs look like, so when the bad germs try to get into their bodies and make them sick, their body will “punch the germ in the nose.”
This helps, but the kids still don’t like getting the shots. Vaccines are a way for your body to be exposed to a virus or bacteria in a way much safer than getting the infection itself. They employ the body’s own natural defenses to do the work.
The Two Kinds of Vaccines
There are two main kinds of vaccines: ones that use weakened forms of the infectious agent and ones that just use proteins from the infectious agent. Vaccines made from the weakened forms are referred to as attenuated virus vaccines, and sometimes cause sickness in people with weakened immune systems. The majority of the vaccines, however, are the form made from proteins that coat the outside of the virus or bacteria.
The whole controversy about vaccines boils down to people thinking they cause more harm than good. Whenever I give a medication, vaccine, or any treatment for that matter, I compare the risk of giving the treatment versus the risk of not giving the treatment. Unfortunately, many people don’t have a clear grasp of either of these when it comes to vaccines. There are certainly some risks with anything we do--vaccines included--but in my personal experience, I think the risk of any of the vaccines I give is small compared to the potential benefit. I wouldn’t give it otherwise.
The Dangers of Not Vaccinating
Unfortunately, vaccines are hurt by their own success. Many of the diseases that vaccines can now prevent are so rare that people don’t take them seriously. The sad fact is that many of these diseases--which can be quite serious--are re-emerging with more people questioning the safety of vaccines. I am all for things being questioned--in fact, science demands we do so--but people should not assume that it’s safer to not give immunizations; doing so can not only increase risk of illness, but it can (and has) result in children dying from preventable diseases.
So, in future articles, I am going to discuss the diseases that vaccines prevent. Perhaps a clearer understanding of what is being prevented will make people think twice before withholding them.
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