Vaccines

The World, 1700's

Smallpox virus was causing an epidemic of huge proportions - millions were dying

In 1717 Lady Montague arrived with her husband, the British ambassador, at the court of the Ottoman Empire (Modern day Turkey). She wrote much about her travels. The following is a letter that she sent to a friend back home in England…

A propos of distempers, I am going to tell you a thing that will make you wish yourself here. The small-pox, so fatal, and so general amongst us, is here entirely harmless, by the invention of engrafting, which is the term they give it. There is a set of old women, who make it their business to perform the operation, every autumn, in the month of September, when the great heat is abated...

People send to one another to know if any of their family has a mind to have the small-pox; they make parties for this purpose, and when they are met (commonly fifteen or sixteen together) the old woman comes with a nut-shell full of the matter of the best sort of small-pox, and asks what vein you please to have opened. She immediately rips open that you offer to her, with a large needle (which gives you no more pain than a common scratch) and puts into the vein as much matter as can lie upon the head of her needle, and after that, binds up the little wound with a hollow bit of shell, and in this manner opens four or five veins.

... The children or young patients play together all the rest of the day, and are in perfect health to the eighth.

Then the fever begins to seize them, and they keep their beds two days, very seldom three. They have very rarely above twenty or thirty in their faces, which never mark, and in eight days time they are as well as before their illness.

... Every year, thousands undergo this operation, and the French Ambassador says pleasantly, that they take the small-pox here by way of diversion, as they take the waters in other countries. There is no example of any one that has died in it, and you may believe I am well satisfied of the safety of this experiment, since I intend to try it on my dear little son. I am patriot enough to take the pains to bring this useful invention into fashion in England, and I should not fail to write to some of our doctors very particularly about it, if I knew any one of them that I thought had virtue enough to destroy such a considerable branch of their revenue, for the good of mankind.

In 1721, at the urging of Montagu and the Princess of Wales, several prisoners and abandoned children were inoculated by having smallpox inserted under the skin.

Several months later, the children and prisoners were deliberately exposed to smallpox.

When none contracted the disease, the procedure was deemed safe and members of the royal family were inoculated.

The procedure then became fashionable in Europe.

It still carried some risk…

Edward Jenner – the “inventor” of vaccines

In the late 1700’s Edward Jenner noticed that milk maids who have had cow pox did not contract small pox…

In 1796 he deliberately infected a boy, James Phipps, with cowpox from a milkmaid.

When the boy recovered, Jenner injected him with smallpox under his skin.

James Phipps didn't catch smallpox.

A worldwide effort to eradicate smallpox started in the 19th century.

The arm of Sarah Nelmes, a dairy maid, who had contracted cowpox. Jenner used material from her arm to vaccinate an eight year old boy, James Phipps.

Edward Jenner, An inquiry into the causes and effects of the variolae vaccinae, a disease discovered in some of the western counties of England, particularly Gloucestershire, and known by the name of the cow pox (1798).

By the early 1970s, a growing number of nations had reached “zero-pox.” In 1975, the last case of variola major, the most virulent form of smallpox, occurred in Bangladesh.

In October, 1977, Ali Maow Maalin of Somalia contracted variola minor, becoming the last person in the world to contract smallpox naturally.

How do vaccines work?

Exposure to pathogen (or pathogen parts) causes an immune response

Antibodies are produced, memory cells are activated Next exposure involves antibodies that fight the pathogen much faster

Four Types of Vaccines

Live attenuated vaccines

Killed vaccines

Toxoid vaccines

Component vaccines

1. Live attenuated vaccines - contain bacteria or viruses that have

been altered so they can't cause disease (in most cases)

- created from the naturally occurring but weakened pathogen itself

Ex. measles, mumps, rubella vaccine (MMR vaccine), oral polio vaccine (OPV)

2. Killed vaccines

•contain killed bacteria or inactivated viruses

• cannot cause an infection, but can stimulate a protective immune response

•Ex. polio vaccine, influenza vaccine

3. Toxoid vaccines

- contain toxins produced by the pathogens that have been made harmless

- stimulate the body to produce protective immunity just like the germs' natural toxins.

Ex. Diphtheria toxoid vaccine, Tetanus toxoid vaccine

                                                                                                                                      

4. Component vaccines

- contain parts of the whole bacteria or viruses

cannot cause disease, but they can stimulate the body to produce an immune response that protects against infection with the whole pathogen

Ex. Hepatitis A, B

Oral polio vaccinations in Ethiopia