Vaccine Development and Manufacture

 HOW ARE VACCINES MADE?

The vaccines that we are provided with have been carefully researched and studied so that it can be, for the most part, safely administered to patients with little to no side effects. The initial research is mostly completed in academic research laboratories and is funded by grants provided by foundations or the government. If the research completed in the labs are successful, the research will be expanded and moved onto larger studies mostly completed by pharmaceutical companies because of how costly the research becomes (Children’s Hospital of Philadelphia).

Different Types of Vaccines

There are actually several different types of vaccines that are used on a regular basis. However, the purpose of each vaccine is the same. A vaccine provides the body with antibodies against a disease to prevent it from getting sick. There are currently five types of vaccines that are available to the general public. According to the National Institute of Allergy and Infectious Diseases, they are the live,attenuated vaccines, inactivated vaccines, subunit vaccines, toxoid vaccines, and conjugate vaccines. There are also two more vaccines that are still in their experimental stages and have not yet been made available to the public. They are the DNA vaccines and recombinant vector vaccines (Children’s Hospital of Philadelphia).

Live, attenuated vaccines

Live, attenuated vaccines are made from a weakened, but still living version of the microbe. When injected into the body, the weakened microbe initiates an immune response that includes the production of antibodies against it while it can still easily fought off by the immune system. The vaccine teaches the body to recognize this microbe as harmful with little to no signs or symptoms and requires only one or two doses for a lifelong immunity to the microbe (National Institute of Allergy and Infectious Diseases).

There are disadvantages to using this form of vaccination. Patients with a compromised immune system cannot be administered the weakened microbe because their immune system may not be able to safely them off. Also, though the microbes are weakened, they are very much alive. Therefore there is always the risk that a single microbe might mutate into a more virulent version and attack the body much more aggressively once injected. Since these microbes are alive and must be kept alive to for the vaccine to remain effective, they must be transported under certain environmental conditions (usually under refrigeration). When these vaccines are being transported to less developed areas of the world, the resources necessary to keep them alive and effective may not be available.

Examples of diseases prevented with live, attenuated vaccines: mumps, chickenpox, measles (National Institute of Allergy and Infectious Diseases)

Inactivated vaccines

Inactivated vaccines are vaccines produced from dead microbes. Living microbes which may cause disease are treated with heat, chemicals, or radiation so that they become inactivated or dead (National Institute of Allergy and Infectious Disease). This eliminates the risk of mutation and makes transportation much less complicated than that of live, attenuated vaccines.

The disadvantage of inactivated vaccines is that the dead microbes create a weaker immune response than live microbes therefore booster shots or doses after the initial dose need to be administered to the body before the body can develop a complete immune response to the microbe.

Example of diseases prevented with inactivated vaccines: polio, influenza (some variants) (Center for Disease Control and Prevention)

Subunit vaccines

Subunit vaccines are vaccines made from the antigens of a disease-inducing microbe. Antigens are either taken from the surface of the microbe or isolated and replicated without the microbe (recombinant subunit vaccine) and then administered into the body. More specifically, some vaccines contain the epitopes or the sites where the body’s antibodies and T cells bind to and recognize (National Institute of Allergy and Infectious Disease). These “subunits” of the microbes can induce an immune response with a relatively low risk of disease manifestation.

The difficulty in creating subunit vaccines is the identifying and isolating of the specific antigens that cause an efficient immune response (National Institute of Allergy and Infectious Disease).

Example of diseases prevented with subunit vaccines: hepatitis B (National Institute of Allergy and Infectious Disease)

Toxoid vaccines

Toxoid vaccines address the toxins that are produced by microbes by introducing the body’s immune system to detoxified versions of the toxins called toxoids (National Institute of Allergy and Infectious Disease). The toxins are treated with a mixture of sterile water and formaldehyde to render them harmless. The immune system recognizes the toxoids and produces the antibodies necessary to combat them.

Example of diseases prevented with toxoid vaccines: diphtheria, tetanus, botulism (National Institute of Allergy and Infectious Disease)

Conjugate vaccines

Conjugate vaccines are vaccines containing antigens or toxoids which help the immature immune system of a child to recognize the polysaccharide protective layer of a microbe and eliminate the microbe. Polysaccharide layer of the microbe is a layer of sugars that prevent a still developing immune system from recognizing the microbe as foreign.

Example of diseases prevented with conjugate vaccines: Haemophilus influenzae type B (Hib) (National Institute of Allergy and Infectious Disease)

DNA vaccines

DNA vaccines are still in development, but the idea is to expose the genes for a microbe’s antigens to the cells in the body and specific cells will incorporate that DNA and begin to produce those antigens. The cells are harmless, but will exhibit the antigens on their surface and act as a vaccine and stimulate the immune system to produce the antibodies for those antigens.

Naked DNA vaccines for influenza and herpes are currently being studied (National Institute of Allergy and Infectious Disease).

Recombinant vector vaccines

Recombinant vector vaccines are also still in development, but they also use genetic material to produce an immune response in the body. The idea is to use the genes of a harmful microbe and insert them into a harmless microbe which then will introduce those genes to the body’s cells to induce an immune response. There’s also the possibility of altering harmless microbes so that the antigens of a harmful microbe is presented on its surface and introduced into the body to produce an immune response.

Some recombinant vector vaccines currently being studied are those for HIV, rabies, and measles (National Institute of Allergy and Infectious Disease).

Sources

http://www.chop.edu/service/vaccine-education-center/vaccine-science/how-are-vaccines-made.html

http://www.niaid.nih.gov/topics/vaccines/documents/undvacc.pdf

http://www.niaid.nih.gov/topics/vaccines/understanding/pages/typesvaccines.aspx

http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/us-vaccines.pdf

http://www.cdc.gov/vaccines/vac-gen/side-effects.htm