How do vaccines actually work?
Contrary to popular belief, not all vaccines are the same! While there are classic examples that most people might be familiar with, there are constant innovations in the vaccine world that we can even see in recently approved vaccinations. It’s also important to note that there are no vaccinations that insert live germs into the body, and vaccines cannot affect our DNA but instead simply help train our immune systems.
1. Attenuated Vaccines
Most people that know of vaccines think of the most common type, wherein live but attenuated (weakened) viruses and bacteria are injected into the body. These foreign agents are weak enough to allow healthy patients to fight off infection and learn the immune system “tools” to combat naturally acquired viruses in a low-stakes environment. Some of the most well-known examples include the measles and chickenpox vaccines.
While attenuated vaccines are the poster-child for all vaccinations, they are not advised for everyone. Only healthy patients should receive these vaccines to ensure that the immune system can overcome even the weakened infections. Remember, these viruses and bacteria are still alive!
2. Non-Live Vaccines
As the name suggests, these vaccines have already killed the viruses and bacteria in question. Thus, they may be more suitable to those with weaker immune systems, such as children or adults with compromised health, because the germs cannot replicate.
The tradeoff, unfortunately, means that these vaccines are less potent and long-lasting, oftentimes requiring multiple doses to be as effective as attenuated vaccines. The most famous example of a non-live, inactivated vaccine is the polio vaccine.
3. Toxoid Vaccines
These vaccines are specifically tailored to treat diseases that produce toxins, also known as poisons. Toxoid vaccines are designed to weaken the released toxins into toxoids, which the body acquires through the vaccination. This process gives the immune system a chance to fight off the toxoid without succumbing to illness. For example, both diphtheria and tetanus produce toxins, and therefore may be preempted with toxoid vaccines.
4. Subunit Vaccines
Once again, the name of these vaccines denotes their nature. Subunit vaccines inject only pieces of a germ (“subunits”) rather than its entirety. These vaccines are still effective because the parts of the germs inserted have all of the antigens--the molecules that induce an immune response through the production of antibodies--included, allowing the body to simulate an immune response without being exposed to the worst effects of an illness. A subunit vaccine is used against the whooping cough.
5. Conjugate Vaccines
These vaccines are designed to combat bacteria with antigens (the foreign trigger for immune responses) that have a coating of polysaccharides (large carbohydrate sugars) that normally help disguise antigens and keep them from being detected by the immune system.
The role of the conjugate vaccine is to connect those polysaccharides to antigens that the immune system is already familiar with, teaching the body to react to the polysaccharides if it cannot recognize the antigens. The recently developed mRNA COVID-19 vaccine is an example of a conjugate vaccine.
Of course, these types are generalized categories that do not encompass ALL vaccinations, as there is constant innovation in this field! Stay tuned to learn more about emerging vaccine technologies!
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