How Do Vaccines Prevent Diseases?

Before vaccinations, diseases like smallpox, polio, and rebella killed or paralyzed or caused serious birth defects regularly. These losses of life and types of suffering are now preventable with extremely small risk. A person born in the United States in the year nineteen hundred had an average life expectancy of forty seven years. As of twenty ten, it was seventy eight years. That's not because most adults never reached old

age in the past. It's because babies and toddlers died way more often of diseases that we now vaccinate against. So today, let's talk about vaccines and the basic science behind how they prevent illness. We'll also go head to head with some of the common myths about vaccines. A Vaccines work based on the fact that once a person has caught a disease of some types, they'll probably be immune to that disease for the rest of their life.

For example, once you've had chicken pox, it's extremely unlikely that you'll ever catch it again. This is because your body will recognize the disease and fight it off. This happens thanks to a process called the immune response. The beauty of vaccines is that they help your body develop these disease recognizing abilities without you needing to get sick in the first place. Here's how the immune response works.

When a virus or or bacteria enters your body under normal circumstances, your immune system will identify it as a potential threat, recognizable because it has molecules on its surface called antigens. If your immune system identifies those antigens as being not from your own body and therefore potentially unsafe,

it'll launch an attack. Your immune system attacks by developing invader specific proteins called antibodies that can destroy the antigen than anything attached to it, or tag it for destruction by immune system cells. After the battle, your immune system will stockpile that antibody and remember how to identify that antigen in most cases forever, so if your immune system encounters antigens of the same type later on, it can

fight the disease off fast. Unfortunately, antibodies are really specific, so if you've had chicken pox, for example, that's great for preventing chicken pox, but useless against other diseases. When a disease infects a person, the germs that cause it multiply thousands and thousands of times until a raging infection is underway, which can have all kinds of unpleasant or even deadly effects. A vaccine provides just enough antigens for the body to recognize them and complete the immune response

process without causing an infection. Vaccines are able to provide that goldilock zone of just enough antigens in two basic ways, through weakened germs or through inactivated germs. Vaccines that use weakened germs are also called live attenuated vaccines. Attenuated means weakened. When this type of vaccine is created, the virus or bacteria is weakened in a lab to the point where it's still kicking and able to reproduce, but it can't

cause serious illness. It might reproduce a couple dozen times instead of thousands, but its presence is enough to cause and complete the body's immune response. Live attenuated vaccines can cause mild illness in some people, a low grade fever, a runny nose, or a few chicken pox spots, but it's maybe a day or two of discomfort, nothing compared to the full blown illness. To weaken the virus or bacteria,

researchers take a specimen from an infected person. They then grow the germ in a test tube, a tissue culture, a chicken egg, or some other foreign host. They pass the germ into a second test tube or whatever, then a third, a fourth, and on and on. The measles

virus was passed seventy seven times. Eventually, the germ gets so used to living in that comfortable test tube or other host environment that it loses its capacity to produce illness in living humans, but will still bear its identifying antigens. Examples of live attenuated vaccines are those for MMR, that is, the diesels mumps and rubella combo vaccine, chicken pox, and the entran nasal form of the flu vaccine. The other

type of vaccines uses inactivated germs. In these, the virus or bacteria has been rendered completely ineffective or dead, although one could argue that viruses aren't really alive to begin with. Researchers accomplish this with compounds like formaldehyde or detergents, which are then separated out from the inactivated germs. Pieces of the germs, including their antigens, go into the vaccine, which can thus trigger the immune response with zero chance of

an actual infection. Unfortunately, the strength of these vaccines tends to wear off over time, resulting in less long lasting immunity, so multiple doses of inactivated vaccines are usually necessary to provide the best protection. Examples of inactivated vaccines are those for heptitis A and B, polio, meningitis strip and and

the injected form of the flu vaccine. Inactivated vaccines are preferable because they're safer, and most bacterial vaccines are this type, but viruses often require live, attenuated vaccines because that's the best we can do to fight them. There are some exceptions. For example, rabies is a virus that's too dangerous to give people in a week ined state because a Rabi's infection is always fatal in humans, so doctors don't want

to take any risks. I'll have to do a whole other episode on how vaccines are developed because it's a big topic. But let's talk about what all goes into a vaccine other than the germ and or its antigen, which could be considered the active ingredient. Every vaccine is unique to the disease in question, but here's the gist. First, many vaccines contain what's called adjuvants, which are helpful substances

that make the vaccine more effective. Very basically, adjuvants a felly poke at your immune system to make it react more strongly to the mild threat that the vaccine poses. Next, you've often got a stabilizer, which is a substance that helps protect the active ingredient as it's stored and transported in different temperatures and levels of jostle. Finally, when vials of a vaccine contain multiple doses, a preservative or disinfectant

is required. This is so that every time a dose is removed by needle, any microbe that, against all odds, comes into the vial with that clean needle is killed in the vial and thus won't be able to cause an infection in the person receiving the next dose of the vaccine. All of these substances are thoroughly regulated to ensure their safety in the amounts in which they're used. Health experts recommend so many vaccines for babies and young

children because they're more risk for serious infections. It's a little bit gruesome, but really important to under stand that the diseases that infants and children are vaccinated against today are truly horrifying. For example, diphtheria, a nose and throat infection that can cause difficulty breathing, heart failure, and paralysis once killed over fifteen thousand children a year in the US alone. Or take meningitis, an infection of the covering

around the brain and the spinal cord. Survivors can face brain damage, deafness, and seizures. Polio once infected up to twenty thousand Americans a year, and survivors are often left paralyzed and dependent on mobility tools for the rest of their lives. Measles doesn't just cause a rash, it can cause brain swelling and even death. Mumps can cause deafness and brain damage, and rebella, which is often transmitted to unborn fetuses during pregnancy, can cause miscarriages or premature births,

and birth defects in survivors. All of this is why researchers have spent so much time, time, and effort and money developing safe vaccines. Still, there's a lot of vaccine uncertainty out there right now, and a lot of concerns circulating, which is fair and healthy. Asking questions is good. So let's address a few of the common ones first. And the elephant in the room is the concern that vaccines

might cause autism. This is, in essence, a lie that was manufactured starting the nineteen nineties by this guy named Andrew Wakefield, who was at that time a doctor. His license has since been revoked. He got a study published in the renowned medical journal The Landset in nineteen ninety eight that supposedly linked the MMR vaccine to autism in children, but when other doctors and researchers started looking at it, they realized that Wakefield study didn't prove that at all.

He had cherry picked his cases and didn't show any real evidence. The Landset retracted the study and apologized for printing it in twenty ten, but due to publicity. The idea of the link still spread. The story even morphed from the supposed culprit being the MMR vaccine to thimerasol, which is a preservative that contains mercury. Lots and lots of further studies have been done that have shown no

link between any vaccines and autism. Also, it later came out that Wakefield was poised to make tens of millions of dollars a year on this diagnostic test that he had patented based on his falsified link. The whole thing has been called one of the most serious frauds in medical history because it has made people feel less safe about saving their children from these terrible diseases. If it helps.

Amid all of this concern, vaccine makers have stopped using thimerasol in just about all vaccines, just to reassure people that they're safe. Next step, let's talk about the concern that vaccines are unnecessary because those diseases are pretty much gone anyway. Unfortunately, the only vaccine preventable disease that's been completely wiped out is smallpox. Other diseases can still spread

through things like international travel that take measles. For example, It was considered gone from the US as of the year two thousand, but as of September ninth, of twenty twenty five, there have been one thy four hundred and fifty four cases confirmed here this year, resulting in one hundred and eighty hospitalizations and three deaths. Any deaths from

a preventable disease are too many. Another fair concern is that babies are too fragile that their immune system is going to get overwhelmed by receiving so many vaccinations at once. But babies get an immune workout all the time on play dates, at church, at the grocery store. Vaccines can't overwhelm a functional immune system, and you would know there would be signs or your health care provider would tell

you if your kid was an exception. There are people who can't receive vaccines because of a weakened immune system, like some patients with cancer. That is part of why public health experts want healthy adolescents and adults to stay up to date on their immunizations too. Vaccines prevent healthy people from getting sick, which means, well, first off, we won't suffer the annoying to painful effects of illness, and

we won't fall behind at home or at work. And second of all, if we don't get sick, we won't pass on an illness to someone more at risk for severe symptoms, including death. Getting vaccinated can save a life. It might be yours, it might be a loved ones. Insurance often covers them, and walking clinics often provide them for cheap Again, it's normal and good to have questions or concerns, and please talk to a healthcare provider if you do. After all, at the end of the day,

I'm just a podcast host. Today's episode is based on the article how vaccines Work on HowStuffWorks dot com, written by Leah Hoy. Brain Stuff is production by Heart Radio in partnership with HowStuffWorks dot Com and is produced by Tyler Klang. For more podcasts from my heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.