Manipulating Biology: Costs, Benefits and Controversies

The History of Vaccines

Introduction

Vaccination has been a technology breakthrough for humanity since its implementation at scale in fighting infectious diseases. At its core, vaccination is a form of preventative care. But in wealthy nations, parents of recent generations have not witnessed the ravages of infectious diseases within their lifetimes. As a result, some parents have come to question the wisdom of subjecting healthy children to a series of injections when there is seemingly no obvious or apparent danger to their children’s health.

Still, the fact remains that vaccination is a critical part of the care of children. Vaccination has dramatically reduced infant mortality over the last century and has even defeated diseases like smallpox globally, and greatly reduced the incidence of other diseases like polio.¹

Smallpox is a deadly contagious disease caused by the variola virus. The virus is transmitted directly from person to person or through infested clothing and bedding, and the disease has a case fatality rate as high as 30%.² It was a leading cause of death in 18^th century Europe and had a mortality rate of 80% in infants.³ Because of the virulence of the smallpox virus, doctors were keenly interested in finding a way to prevent or reduce its impact. Perhaps this is why the first progress towards vaccines was centered on preventing smallpox.

So where did the idea of vaccines come from?

China

Claims have been made that the practice of inoculation against smallpox in China date back as far as the tenth century, but reliable records would indicate that the practice dates back to the 16^th or 17^th century, still predating the European breakthroughs in vaccination.⁴ The Chinese method of inoculation is called variolation and involves using the ‘live’ or disease-causing form of smallpox virus.

Variolation practices sometimes include the use of a needle or similar tool to place dried and powdered smallpox scabs or fluid into the skin of a non-afflicted individual, with the aim of creating a milder infection with a lower mortality rate, of between 2% to 3%.⁵ The hope is that after treatment the inoculated person will be less susceptible to the more intense, deadly form of the smallpox virus.

The Manchu Imperial family, which ruled China from the 17^th through early 20^th centuries, desperately avoided contracting smallpox. Measures included not allowing the first Manchu ruler, Shunzhi, to enter the capital city. He contracted smallpox and died anyway – as did large numbers of his troops following the conquest of China.⁶ His successor would implement variolation in 1681. In 1742 the practice of variolation was officially adopted and legitimized by the Imperial court, making it a mainstay of Chinese medical practice,⁷ and by 1807, charities in China began offering the variolation inoculation for free.⁸

It took time for the practice of variolation against smallpox to spread across China. Political necessity on the part of the ruling family saw them adopt the practice, and in so doing, added legitimacy to it. The practical benefits of variolation outweighed the risks, with 2% to 3% dying from variolation as compared to a 30% mortality rate for a full blown virus infection.

While China saw success with its practices, it would rapidly adopt the later developed findings from Europe, often attributed to Edward Jenner.

Europe

Edward Jenner (1749 – 1823) was a doctor and variolator in England, who with the help of his nephew, Henry Jenner, collected epidemiological evidence on 28 individuals between 1792 and 1797, which he used to create a hypothesis.

In particular, Jenner was interested in local beliefs that milkmaids seemed to be immune to smallpox. After seeing a supportive correlation in the data, Jenner took a sample of cow pock from a diary maid named Sarah Nelmes, and inserted it into the arm of a boy named James Phipps. The vaccination produced a lesion only at the inoculation site unlike variolation and did not cause serious illness.⁹

Jenner then subjected Phipps to a variolation treatment using live smallpox virus. Phipps did not become ill, which convinced Jenner that he had found a safe inoculation.¹⁰ This seemed to confirm Jenner’s theory: Perhaps cowpox could confer a protection against smallpox infection, and those routinely exposed to cattle that had contracted cowpox were thus immune.¹¹

Jenner’s work prompted the spread of his vaccination technique, and laid the foundation for other scientists to build deeper understandings of disease spread and prevention. Jenner’s legacy continued well beyond his death. The last recorded natural case of smallpox on the planet occurred in 1977. Shortly afterwards in 1980, the World Health Organization declared the disease was eradicated, following a global effort to vaccinate as many humans as possible against the virus.¹²

Despite the massive impact of vaccines, Jenner did not fully understand why his method worked because he did not understand the germ theory of disease. Understanding the germ theory allowed science and medicine to take Jenner’s discovery to the next level.