Week 4 (Part 1): History of Vaccines Flashcards
Define vaccination:
Vaccination is the intentional exposure to pathogens in a form that cannot cause an infectious disease
What is the purpose of vaccines?
- Direct vs. Indirect?
Purpose of a vaccine is for the recipient to develop long-term immune protection against the pathogen
- The objectives of immunization programs are to prevent, to control, to eliminate or to eradicate vaccine-preventable diseases by directly protecting vaccine recipients and indirectly protecting vulnerable individuals who may not respond to vaccines or for whom vaccines may be contraindicated
Who was Benjamin Jesty?
During that time, an English farmer named Benjamin Jesty personally took charge of inoculating his wife and children with fresh matter from a cowpox lesion in one of his cows out of fear of having his wife and children become victims of the smallpox epidemic.
- He applied this method after having contracted cowpox himself and believing he was immune to smallpox.
- He never published his results even though his wife and children did not show symptoms after being exposed to smallpox
Who was Edward Jenner?
An English physician named Edward Jenner (1748–1823) searched for a cure for smallpox, a debilitating disease that rendered the world helpless.
- Jenner became interested in certain individuals who were immune to smallpox because they had contracted cowpox in the past.
- He personally witnessed this when he learned of a dairymaid that was immune to smallpox due to her previous infection with the cowpox virus, usually transmitted from infected cattle
After many speculations on the role of cowpox and its immunizing effect against smallpox, Jenner, in 1796, inoculated an 8-year-old boy named James Phipps using matter from a fresh cowpox lesion on the hands of a dairymaid named Sarah Nelms who caught them from her infected cattle.
- After several days, Jenner inoculated the boy again but this time with fresh matter from a smallpox lesion and noted that the boy did not acquire the disease proving that he was completely protected
Vaccination against smallpox has another distinction:
It is the first and so far, only procedure that has fully eliminated/eradicated the disease, with the important consequences that we do not need to worry about the disease and, furthermore, that this vaccine is no more needed, and all smallpox-related costs are saved globally.
What was smallpox eradicated?
- Smallpox declared eradicated in 1980.
Who advanced vaccines in the 1870-80’s?
- Created?
- Principle?
Next major advance by Louis Pasteur in 1870-80’s - A French chemist and microbiologist, was the first to propose the “Germ Theory” of disease in addition to discovering the foundations of vaccination
- Created vaccines against chicken cholera, anthrax, rabies
- Principle: “isolate, inactivate using heat and inject”
What happened in Louis Pasteurs experiment?
Pasteur started his experiments by intentionally infecting chickens by feeding them cholera-polluted meals and then recording the fatal progression of the illness.
- At first, Pasteur was using fresh cultures of the bacteria to inoculate the chickens, most of which did not survive.
- During that time, Pasteur had to go on a holiday, so he placed his assistant in charge of injecting the chickens with fresh cultures.
- However, his assistant accidentally forgot to perform the injections, and the bacterial cultures were left in a medium that was exposed to room air for about a month.
Later, the attendant injected the chickens with the now “attenuated” strain of bacteria resulting in mild, non-fatal symptoms.
- Pasteur later re-injected these chickens, but this time with fresh bacteria.
- To his surprise, they did not get ill.
- Ultimately, Pasteur reasoned that what made the bacteria less deadly was exposure to air, mainly oxygen.
You can see here that the 1900s proved to be a…
… proliferative time in vaccine study and development, which now shapes our current vaccination schedule funded by the government.
- Ongoing study leads to changes and advancement of these vaccines within the population
How many infectious diseases have vaccinations controlled?
- Examples
Vaccination has controlled 14 infectious diseases:
- Smallpox - Poliomyelitis
- Rabies
- Measles
- Haemophilus influenzae type b
- Rubella
- Tetanus
- Hepatitis B
- Pertussis
- Yellow Fever
- Typhoid
- Mumps
- Diptheria
- Rotavirus
What is one of the most important accomplishments to public health?
- What occurred before?
- Present day?
Vaccinations - they are integral to our health
- Before vaccines became available, many Canadian children were hospitalized or died from diseases such as diphtheria, pertussis, measles and polio.
- Today, although these disease-causing bacteria and viruses still exist, such diseases are rarely seen in Canada.
IF the current vaccination programs were reduced or stopped, what would occur?
- Where has this been observed?
IF the current vaccination programs were reduced or stopped, diseases controlled through immunization would re-appear in Canada.
- This phenomenon has been observed in other countries where large epidemics occurred following a decline in immunization rates, resulting in many preventable hospitalizations and deaths
When is immunization important?
- Immunization is important in all stages of life.
Descrive Diptheria:
- Infection results from and damages what?
- Fatality pre-vaccine era?
Infection of the throat causes severe breathing difficulty which may result in asphyxia.
- Infection also results in the dissemination of diphtheria toxin, which damages the heart and central nervous system.
- In the pre-vaccine era case fatality was about 5% to 10%, with the highest death rates occurring in the very young and the elderly.
Describe poliomyelitis:
- Paralysis occurs in what %?
- Children vs. adult death?
Paralysis occurs in less than 1% of infections but among those paralyzed, about 2% to 5% of children and 15% to 30% of adults die.
