pathoscribe

Written by Yong-Lin Hu | Art by Anoushka Pandya

Throughout history, vaccines have played a vital role in eradicating the spread of numerous diseases, as well as promoting herd immunity, which has proven critical during epidemics and pandemics. In modern times, the role of vaccination has become increasingly prevalent, showcased by its importance during the height of the COVID-19 pandemic. More than ever, the development and efficacy of vaccines were scrutinized, as many saw firsthand the value of the vaccine in 2021. 

According to the U.S. Department of Health and Human Services, vaccines can help “immune systems fight infections faster and more effectively” because when administered, they imitate an infection, sparking the body’s natural defense: antibodies. Antibodies fight off specific germs and are activated by antigens, which are the active ingredient in all vaccines. By kickstarting the immune response towards a specific represented germ in the vaccine, the body can become more accustomed to the germ and know the necessary defense systems. Because of this, when a person is infected by a virus they already have a vaccination for, the “trial and error” process seen with vaccines is cut out. The body can immediately start fighting the virus. This significantly reduces the likelihood of developing a severe illness.

Because of the nature of vaccines, intensive testing and development are needed before vaccines are approved and can be widely distributed. On average, a vaccine takes around 10 to 15 years to develop. In the United States, this process is typically conducted by private companies. It starts by first finding the causative agents of the specific disease. This can include a virus, bacteria, fungi, or parasite. These agents are then grown in a laboratory–there has to be enough to sample for vaccine testing, which can be difficult, depending on the specific environment they thrive in. While doing this, scientists study the agent to pinpoint and understand the specific part that triggers the immune system response to be incorporated into the vaccine. With the development of the mRNA vaccine, scientists only need to find and replicate the genetic code of the agent to develop the vaccine. After a vaccine is initially developed, it will undergo preclinical tests, where it will be administered to lab-grown cells and laboratory animals, including mice and monkeys. Computer technology can also be used to help predict how laboratory tests will go to ensure there are no severe health side effects and that it triggers a defense response. Vaccines will return to the development phase until adequate results are produced.

After this, a company will send the FDA an extensive application to begin human testing, elaborating on the development process, lab findings, proposed human study outline, and more. It must be approved by an ethics committee and by the FDA before the three stages of clinical studies can begin. In the first phase, 20 to 80 adults test the vaccine first. The main priority here is to ensure the vaccine is safe and prompts a response by the immune system. In the second phase, trials expand to several hundred people, which are generally randomized and controlled. Here, researchers focus on the efficacy of the vaccine, side effects, best dosage, technique to give the vaccine, and how to time the doses. With successful phase 1 and 2 trials, clinical trials will finally proceed to phase 3, which involves thousands to tens of thousands of people. Trials are randomized and double-blind (meaning that neither the researcher nor participant knows which treatment they receive), and the main goal is to test efficacy and rare side effects. After all three clinical trials are successful, the vaccine developers will apply for a license from the FDA. Data, necessity, manufacturing, etc are all considered before approval. After approval, the FDA and CDC will periodically inspect production facilities and vaccine data.

The first successfully developed vaccine was made by Dr. Edward Jenner to combat smallpox–one of the most devastating diseases that plagued the world for over 3,000 years. Although the discovery of vaccines came only in 1796, a conceptually similar practice, known as variolation, was believed to have existed from at least the 15th century. Variolation was a technique where individuals were deliberately infected with mild forms of smallpox. To do so, the fluid from smallpox pustules was taken from infected individuals and transmitted through small cuts, or in other cases, dried smallpox scabs were blown into the nose. Only around one to two percent of those variolated died, a significant improvement from the 30% when contracted naturally. This practice originated in Asia, but it eventually spread to Africa, India, the Ottoman Empire, and eventually Europe in 1721.

Later on in 1774, scientist Benjamin Jesty made a breakthrough after he hypothesized that receiving an infection with cowpox could provide a person with smallpox resistance. This would serve as the basis for Dr. Edward Jenner’s discovery. When he collected matter from a cowpox sore and infected an 8-year-old James Phipps with it, he learned that despite a minor reaction that followed, Phipps had developed immunity. While vaccines, in theory sound, similar to variolation, what differs is the usage of a much safer and rarely transmitted disease source. Cowpox is a bovine virus, meaning that it predominantly affects cows and other animals but has the potential, albeit unlikely, to transmit to humans. The term “vaccine” stems from the Latin word for cow: Vacca.

In modern times, vaccines have been used as a regular protective measure for all individuals with a variety of purposes. These include the all-too-known flu shot, DTaP, HepB, and COVID-19 vaccines, some of which are mandated across different ages and in school.

Sources:

Office of Infectious Disease, and HIV/AIDS Policy (OIDP). “Vaccines Protect You.” HHS.Gov, 27 Apr. 2021, https://www.hhs.gov/immunization/basics/work/prevention/index.html#:~:text=When%20you%20get%20a%20vaccine,won’t%20make%20you%20sick. Accessed 25 Aug. 2024. 

“Vaccine Development, Testing, and Regulation.” History of Vaccines, https://historyofvaccines.org/vaccines-101/how-are-vaccines-made/vaccine-development-testing-and-regulation. Accessed 25 Aug. 2024. 

Smallpox: Variolation. https://www.nlm.nih.gov/exhibition/smallpox/sp_variolation.html#:~:text=In%20Asia%2C%20practitioners%20developed%20the,individual%20was%20immune%20to%20smallpox. Accessed 25 Aug. 2024. 

CDC. “Vaccine Basics.” Vaccines & Immunizations, 10 Aug. 2024, https://www.cdc.gov/vaccines/basics/index.html. Accessed 26 Aug. 2024.