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How Do Vaccines Work?

    How Do Vaccines Work?

    Since they were discovered and first formulated, vaccines have saved millions of people from disease. In fact, vaccines are arguably the most important advancement in medical science, especially when it comes to maintaining good health.

    Despite this, there remains a lot of misinformation about vaccines. A recent survey we at Hello Doctor conducted found that only 45% of respondents are aware of all vaccines that are recommended for adults.

    In order to clear things up, we will be answering the question of “how do vaccines prevent disease?” to better understand why this is so important to our health.

    How Do Vaccines Prevent Disease?

    What is a vaccine?

    In order to answer the question of “how do vaccines prevent disease?”, we first need to talk about what a vaccine is.

    A vaccine is a type of medicine that boosts a person’s immune system to protect the body against diseases. These are usually injected directly into the body, but some vaccines can be taken orally, and a few vaccines can be applied directly to the skin.

    Vaccines work by training the body’s immune system to fight against various diseases. You can think of vaccines as a training guide for the immune system.

    Vaccines do this by imitating an infection, which causes the immune system to respond in kind. This way, the immune system can safely learn how to fight off infection and remember it for the future.

    This means that if a vaccinated person gets exposed to a certain disease, their body knows how to respond, and can fight off the disease before anything bad can happen.

    What are vaccines made of?

    Scientists have developed different ways to create vaccines depending on what disease it is effective against.

    Here are the different types of vaccines available:

    Live attenuated vaccines

    Live attenuated vaccines are made from modified versions of disease-causing viruses and bacteria. After administration, these pathogens are still able to replicate in the body, however, they no longer have the harmful or infectious properties.

    Therefore, the virus or bacteria in a vaccine does not cause the same symptoms as an actual infection and the recipient will not be infectious.

    However, live attenuated vaccines should not be given to people with weakened immune systems or those diagnosed with HIV or similar health problems. This is because even if it is an altered form of a pathogen, their immune system may not respond adequately to suppress its growth or replication.

    But for most healthy individuals, live attenuated vaccines are perfectly safe, highly effective, and long-lasting. In the chance that a vaccinated person still gets infected, their symptoms will be much milder.

    Inactivated vaccines

    Inactivated vaccines are essentially “dead” viruses or bacteria that are injected into the body. Even if the disease is already inactivated, the immune system still responds to the infection, and can still learn how to fight it off.

    Compared to live attenuated vaccines, inactivated vaccines do not have the ability to replicate in the body. This is why inactivated vaccines require several booster shots for a person to develop full and continuous immunity.

    However, unlike live attenuated vaccines, inactivated vaccines are safer to administer to young children, elderly adults, and immunocompromised patients. Pregnant women are also allowed to get this type of vaccine.

    Subunit/conjugate vaccines

    Subunit or conjugate vaccines differ in that they use specific proteins or carbohydrates of the disease. This means that there is almost no risk of using subunit or conjugate vaccines since it is not the actual disease itself.

    When injected into the body, the immune system treats the vaccine as infection and can react in kind.

    The drawback to subunit/conjugate vaccines is that identifying the specific chemicals to isolate from the disease is not always easy or even possible. This is why these types of vaccines are only applicable for certain diseases and not all of them.

    Toxoid vaccines

    Toxoid vaccines are similar to inactivated vaccines in that they use deactivated toxins to train the body’s immune system.

    The immune system can then learn how to fight off the actual infection based on these deactivated toxins alone.

    DNA vaccines

    DNA vaccines are currently still being tested and are an experimental form of vaccines. These vaccines use DNA strands from the disease in order to teach the immune system how to develop a resistance to it.

    The great thing about DNA vaccines is that they are very effective, and also cheap to produce. But at the moment, they are still being tested and studied for human use.

    Recombinant Vector Vaccines

    These types of vaccines are similar to DNA vaccines in that they use the DNA of a weakened virus or bacteria and “dress” it in the DNA of a more dangerous disease.

    This means that the immune system can learn how to deal with both of those diseases at the same time. However, just like DNA vaccines, these are still in the experimental stages and still being studied by scientists.

    What Diseases Can Vaccines Help Prevent?

    There are numerous serious diseases that are vaccine-preventable. These include:

    Consult your doctor regarding vaccines for your children or yourself.

    How Safe Are Vaccines?

    It is possible for certain vaccines to have side effects in some people. The most common are injection-site reactions and mild flu-like symptoms. However, the chance of developing severe adverse effects is rare. The benefits outweigh the possible risks.

    Some people mistakenly believe that vaccines cause autism, but in reality, we do not even know the cause of autism. Plus, autism has been found to start in the womb, so it is impossible for vaccines to cause autism.

    Additionally, only doctors or other certified professionals should administer vaccines, following a set vaccination schedule. This helps ensure that the person being vaccinated will not experience any harmful side effects from the vaccine.

    Vaccines Also Benefit Those Who Are Not Yet Vaccinated

    Not everyone can get every vaccine, any time they want to. For example, newborns and infants are unable to receive a majority of vaccines until they have reached a certain age. As mentioned previously, those with immunocompromising conditions may not be eligible to receive certain vaccines. Additionally, there are groups of people who do not have access to or simply opt out of vaccinations. This is where the concept of herd immunity comes in.

    Herd immunity happens when a large amount of the population is immune to a certain type of disease. Since most people are immune, they also will not pass the pathogen to those who have not yet been vaccinated, essentially protecting the unvaccinated population.

    This is very important in babies, whose immune systems are still developing, and for people with serious illnesses who cannot be vaccinated.

    People with HIV or AIDS also greatly benefit from herd immunity since they themselves cannot be vaccinated against certain diseases.

    This is why it is important to get complete vaccinations to not just protect yourself, but others as well.

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    Hello Health Group does not provide medical advice, diagnosis or treatment.


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    Written by Jan Alwyn Batara Updated Apr 28
    Medically reviewed by Mia Dacumos, MD