History and Description of Vaccines and Herd Immunity

When discussing the history of vaccines, most people begin in 1796 with the invention of the direct predecessor to modern day vaccines.[1] However, the story actually “begins with the long history of infectious disease in humans, and in particular, with early uses of smallpox material to provide immunity to that disease.”[2] “Evidence exists that the Chinese employed smallpox inoculation (or variolation, as such use of smallpox material was called) as early as 1000 CE. It was practiced in Africa and Turkey as well, before it spread to Europe and the Americas.”[3]

The first modern vaccine, which was a vaccine for smallpox, was developed by Edward Jenner in 1796.[4] It would take nearly a hundred years before the next vaccine, one for rabies, would be developed.[5] However, after that vaccine was introduced many started being developed and in the 20th century numerous vaccines were created that helped control, and sometimes even eradicate, certain diseases that had previously ravaged humanity and had caused a great deal of death and hardship throughout the centuries.[6] Perhaps the most famous example is smallpox, which, unlike some diseases like polio, isn’t just gone in part of the world, but has been completely eradicated in the wild (although some samples of the virus are maintained in laboratories for research purposes) with the last known cases occurring in the 1970s and the disease being officially declared eradicated soon thereafter.[7]

The power of vaccines cannot be understated. Vaccines have helped save countless lives and have helped make life as we know it possible.[8] “The introduction of vaccines . . . has been one of the most important contributions to public health of the last century, ranking second only to the advent of clean water. Diseases like smallpox, polio, measles, mumps, rubella (MMR), and whooping cough were by far and away the major killers of human beings until the beginning of the 20th century. Nowadays, these diseases have been dramatically reduced or even eliminated in the Western world as a result of large- scale vaccination programs.”[9]

There are multiple types of vaccines, each with their own advantages, disadvantages, and approach to introducing antigens to your body in order to prepare and protect your immune system, but to put it simply, vaccines work by introducing antigens from pathogens into your body in order to prepare your body to combat the pathogen later.[10] “By injecting these antigens into the body, the immune system can safely learn to recognize them as hostile invaders, produce antibodies, and remember them for the future. If the bacteria or virus reappears, the immune system will recognize the antigens immediately and attack aggressively well before the pathogen can spread and cause sickness.”[11]

While getting yourself vaccinated is important to protect yourself, it also protects society as a whole through the concept of “herd immunity.”[12] Basically, “[o]nce enough people are immunized, opportunities for an outbreak of disease become so low even people who aren’t immunized benefit. Essentially, a bacteria or virus simply won’t have enough eligible hosts to establish a foothold and will eventually die out entirely.”[13] To put it differently, “when a critical portion of a community is immunized against a contagious disease, the virus can no longer circulate in the population, so that the disease cannot gain foothold in that society.”[14]

Herd immunity is important because it reduces the rates of diseases and allows for persons who cannot be vaccinated to be protected.[15] The specific threshold of the population that needs to be vaccinated in order for herd immunity to be effective varies depending on the disease.[16] “For some diseases, herd immunity can go into effect when 40 percent of the people in a population become immune to the disease, such as through vaccination. But in most cases, 80 to 95 percent of the population must be immune to the disease to stop its spread.”[17]

[1] All Timelines Overview, History of Vaccines, https://www.historyofvaccines.org/timeline/all (last visited Apr. 22, 2020).

[2] Id.

[3] Id.

[4] Kevin M. Malone & Alan R. Hinman, Vaccination Mandates: The Public Health Imperative and Individual Rights, CDC,https://www.cdc.gov/vaccines/imz-managers/guides-pubs/downloads/vacc_mandates_chptr13.pdf (last visited Apr. 21, 2020). This was the first modern vaccine and is

[5] Id.

[6] Malone & Hinman, supra note 4.

[7] Frequently Asked Questions and Answers on Smallpox, WHO, https://www.who.int/csr/disease/smallpox/faq/en/ (last visited Apr. 22, 2020); Smallpox, CDC, https://www.cdc.gov/smallpox/index.html (last visited Apr. 21, 2020).

[8] Roland Pierik, On Religious and Secular Exemptions: A Case Study of Childhood Vaccination Waivers, 17(2) Ethnicities 220 (2017) (available at https://journals.sagepub.com/doi/pdf/10.1177/1468796817692629).

[9] Pierik, supra note 8.

[10] How Vaccines Work, Public Health, https://www.publichealth.org/public-awareness/understanding-vaccines/vaccines-work/ (last visited Apr. 22, 2020).

[11] How Vaccines Work, supra note 10.

[12] Pierik, supra note 8; How Vaccines Work, supra note 10.

[13] How Vaccines Work, supra note 10.

[14] Pierik, supra note 8, at 221.

[15] How Vaccines Work, supra note 10 (“[T]here will always be a percentage of the population that cannot be vaccinated, including infants, young children, the elderly, people with severe allergies, pregnant women, or people with compromised immune systems. Thanks to herd immunity, these people are kept safe because diseases are never given a chance to spread through a population.”); Pierik, supra note 8, at 224.

[16] Pierik, supra note 8; How Vaccines Work, supra note 10.

[17] Noreen Iftikhar & Stacy Sampson, What Is Herd Immunity and Could It Help Prevent COVID-19?, Healthline (Apr. 2, 2020), https://www.healthline.com/health/herd-immunity.