Vaccines have been made ever since Edward Jenner created one for smallpox in the late 18<sup>th</sup> century. The 19<sup>th</sup> century saw a handful of vaccines created while the 20<sup>th</sup> witnessed a boom in creation. Today the process of making a vaccine in the United States is highly regulated by the FDA as well as the CDC. However, creating a vaccine is not a straightforward process. There are multiple ways in which a virus or bacteria and be used to create a vaccine that will protect a person for years to come.
One such way is to use a weakened form of the virus. The virus is still alive, but its ability to replicate is decreased a many fold. Because the virus cannot not replicate normally a healthy immune system can kill it so there is no disease. The immune system will also be able to recognize the virus in the future and quickly destroy it. This way of making a vaccine almost always ensures life-long protection, however it is not recommended for people with weakened immune systems; a weak immune system may not be able to respond to even a weakened form of a virus.
Immune systems can also respond to inactivated (killed) viruses. This method ensures that there is no possibility of getting the disease, therefore it is recommended for weak immune systems. Since the immune response is somewhat weaker, total protection from the virus may require multiple injections over a period of time.
A third method of vaccine creation is to use only a part of a virus or bacteria, such as a protein. This part can be identified by the immune system which will speedily signal a response when recognized in the future. Similar to using an inactivated virus, a vaccine such as this will in no way harm a patient with a weak immune system but may require multiple doses to ensure full protection.
After a vaccine is made, it goes through multiple testing phases to ensure safety and efficiency. All of these phases are closely regulated by the FDA, CDC, and the company wishing to produce the vaccine. Before a vaccine becomes available on the market it has been tested on thousands of people. And even after a vaccine is publically available it is still monitored.
Multiple efforts are put into the creation and testing of a vaccine. Because of such creation the quality of life and life-expectancy we have today have greatly increased. Vaccines are powerful tools that when wielded correctly and save many lives.