Types of Vaccines

Vaccines are all about instructing your immune system how to effectively fight off several vaccine preventable diseases. Here are the different ways they do it:

 

Live attenuated:

            Live attenuated vaccines are derived from whole living microbes which are then weakened in a laboratory setting. In a safe lab environment, they are passed through several generations and pick up weakened mutations over time. This way the immune system can build immunity to the virus or bacteria without the individual getting sick. The weakened microbe when introduced in the body will target the immune system directly in order to trigger the immune response to create antibodies against the disease without causing disease in the individual. These vaccines are extremely effective as well and typically do not need the support of an adjuvant as this type of vaccines represents the closest thing to the actually pathogen. When receiving the appropriate amount of doses of these vaccines it can result in life long immunity to the disease. One disadvantage of live-attenuated vaccines is that they typically cannot be administered to immunocompromised individuals. This is why herd immunity is so important! Vaccine preventable diseases that use live vaccines are Measles, Mumps, Rubella, Rotavirus, Varicella, and Influenza. 

 

Killed:

            Killed vaccines, also known as inactivated vaccines, are vaccines that take the live pathogen of target and kill or inactivate it. These pathogens can typically be killed through heat or chemicals like formaldehyde. This way the killed pathogen that is introduced to the immune system can help the immune system to create memory against the disease but will not cause the individual to be sick with the disease. These vaccines typically need boosters to maintain immunity which is why getting boosters is so critical. Vaccine preventable diseases that use killed vaccines are Hepatitis A, Polio, and Influenza. 

 

Toxoid:

            Toxoid vaccines are specifically geared towards bacteria that produce toxins which are poisonous to the human body. If an individual were to be infected with such a disease, once the bacteria entered the body the toxins would begin to replicate and spread systemically. In order to prevent this, this is where toxoid vaccines come into play. Toxoid vaccines are prepared by taking these dangerous toxins and inactivating them with chemicals or heat so they cannot cause illness in the individual. From there the immune system can recognize those non-harmful toxins and the body builds memory of how to fight off the toxins in the case of encountering it so the individual will not experience any illness. Toxoid vaccines are super important and typically require boosters. Vaccine preventable diseases that use toxoid vaccines are Tetanus and Diphtheria. 

 

Conjugate:

            Conjugate vaccines are specific to diseases that are caused by encapsulated bacteria which contain antigens. Encapsulated bacteria contain a polysaccharide coating that covers the antigen which makes it hard for the immune system to recognize the antigen on its own with the absence of a vaccine. Conjugate vaccines consist of a carrier protein such as a tetanus toxoid carrier protein and a polysaccharide. This allows the immune system to recognize that the polysaccharide that is found on the encapsulated bacteria is harmful and the immune system can build memory to it so if were ever to be encountered it would know how to fight off the bacteria before illness was caused. Conjugate vaccines are especially important for children under the age of five years old as their immune systems are underdeveloped and they cannot recognize encapsulated bacteria. Conjugate vaccines give the immune system a “hint” or instructions that the antigens are covered by a polysaccharide coating. An unvaccinated child is especially at risk for these diseases as the body does not know how to fight off against it on its own. This vaccine like others typically need boosters. The vaccine preventable diseases that use conjugate vaccines are Haemophilus Influenzae B, Meningococcal disease, and Pneumococcal disease. 

 

Subunit:

            Subunit vaccines are super cool in the fact that they only contain parts or fragments of the pathogen, also known as subunits. They typically contain proteins that have the ability to induce an immune response and create memory without the individual getting sick. These vaccines are extremely safe and stable and most importantly specific to the pathogen at target. Vaccine preventable diseases that use subunit vaccines are Hepatitis B, HPV, Pertussis, and Influenza. 

 

mRNA:

            mRNA vaccines can be described as giving your cells instructions or a blueprint on how to make a protein that can trigger an immune response inside the body. From this the immune system can recognize that protein and create an immune response to build memory to the protein so if were ever naturally infected it would know how to fight off the pathogen. For example, for the Covid-19 vaccine mRNA is isolated from the spike protein and developed in a lab and once an individual gets vaccinated that mRNA will enter the cell and the Covid-19 virus spike protein is developed and presented on that cell. From there the immune system recognizes that protein and antibodies specific to Covid-19 are produced. Throughout this whole process you do not get sick which is important to note. So in the future, if you are then infected with Covid-19, the antibodies produced from the vaccine will hinder the virus from replicating in the body and prevent the illness entirely or sever illness. A common argument people have with the Covid-19 vaccine has to do with the fact that the mRNA vaccine exposes the body to the spike protein. However, if you were to get naturally infected with Covid-19 your body would be exposed to so much more of the protein and the entire virus itself as it would replicate rapidly.