Animal Sciences - Vaccines and Vaccine History

Secondary eposure

Faster And stronger immune response

Disease Eradication

Disease is extinct

Examples

• small pox

  • 20-60% dealth rate

  • 300-500 million dealths (20th century)

  • ~ 50 million dealths (early 1950’s)

• Rinderpest

  • Cow disease also called cattle plauge

• Close to Plio

Disease Elimination

Reduction to zero of an infectous agent in a defined GEOGRAPHIC area

It can still get into the grography via tourists by will not cause an outbreak becuse of vaccinations

Canada has elimination status for polio, measles, mumps, and rubella

Benifits of Vaccination

• Disease eradications

• Local elimaination

• Control of mortality, morbitiy and complications

  • some protect when administered after exposure (rabies)

• Mitigation of disease severity

• Prevent ~ 6 million dealths per year

• Diseases reduced in developed countries by 98-99%

• For mesales a 78% decaline in mostality 12.7 million deaths avodided (2000-2008)

Small Pox

• Acient disease

• 30% mortality

• 18th centurey europe

  • 400,000 deaths per year

• Variola Virus (DNA virus)

• Eradicated 1977 Due to

  • Vaccination and World Heaht Organization (WHO)

Variolation

• developed in Asia

• Delibriate infection with smallpox

• LOW DOSES

  • inhalation of dried smallpox scabs(Asia)

  • Skin Puncture (Eruope America)

• 1-2% fatalities

• Survivors “vaccinated (resistant) to small pox infection

• 30% fatality rate is not “vaccianted” and naturally exposed to smallpox

John Fewster (1738-1824)

• counrty surgeon

• Practiced Variolation

  • noticed soem pations dis not respond to smallpox inocualtion

• Determined that the “non-responders” had been infected with cow pox before

• Presented a paper the the medical society of london entitled “cow pos and its ability to prevent small pox” (1865)

Edward Jenner

• Country physician

• Advanced understading of anginal pectoris

• Created Jenners Vaccine

Jenner’s Vaccine (1796)

Matter taken from a dairymaid’s fresh lesions

Cowpox: cross-immunityr to small pox

Cowpox-> Child→ gets infected with cowpox→ now immune to smallpox

Experiment recrated on ther children including his own son

Jenner was riddiculed and was called repulsive and ungodly

Rinderpest

• Cattle plague

  • concidered the deadliest cattle disease with 100% death rate in some heards

• RNA virus

  • related to measles, mumps, and Mipah

• Transmistion

  • animal to animal contact

  • Virus present in Nasal secritaions preclinicaly

• Global vaccination program

  • declared eradication 2010

Heard protection

• Reduction in Disease incidence in Unvaccinated indiviuals when sufficent prportion of populaiton is vaccinated

  • unablet to genreate immune response (immuocomprimised, elderly, infant)

• Diseases with high Ro (Measles) require higher coverage to attain hear protection that a disease with a lower Ro

Ro

Reproductive number of infection

• number of indiviuals that will contract the infection from a single infected individual

• How fast disease is expected to spread

• NOT a measure of disease sevarity

Calcualting Pathogent’s Ro?

• infectous period, contact rate, and mode of transmission

Ro<1

• diease will die out on its own

• For every one sick indifdual, fewer than one new infetion will arise

Ro=1

• an existing infection causes one new infection

• Maintain stable rate winthin a n affected population (no epidemic)

Ro>1

• an exiting infection causes more than one new infection

• Spread in population causeing epidemic

MMR Vaccine

• MMR = Measles, Mups, & Rubella

• Vaccine introduction in 1971

  • in canada adults borns before 1970 are generally presumed to have acuired natural immunity to measles

Canada

• eliminated measles in 1998

  • coverage is BELOW the minimum needed to maintain measles elmination

  • Canada estimated 1st dose covreance :90% of population

  • Required dose vaccination coverage :95%

Vaccine testing and development

• ANimal testing

  • saftey

  • Immunogenicity

  • Efficacy

• Clinical Trials

  • 3 phases

• This is an expensive and LONG process

Traditional Vaccines

• Live-attenuated Vaccines

• Inactivated Vaccine

• Subunit Recombinant Vaccines

Live-attenuated vaccines

• weekened (attenuated) form of the virus

• Strong longlsting immune response

• Dont cause disease but cause immune respose

Examples

• measles, mumps, rubells

Inaccivated Vaccine

• “killed” virus (heat chemicals, or radiation)

Examples

• hepatits A, Flu, Rabies

Subunit Rcombinant Vaccines

• Protiedn Subunit

• Make a protien/peice of virus and inject that

• No potential of infecting, but can be inifective

Examples

• hepititis B, Shingles

RNA Vaccines

Advantages

• Quick To genreate

• Vry sfa e

• Effective

Disadvatages

• RNA labile/degrades

• Must be stored at low temperatures

“The Cutter Incident”

• polio Vaccine 1955

  • flaw in the Salk polio vaccine manufacturing process

  • Cutter laboritories

  • Production of live polion virus in an “inactivated” vaccine

• 120,000 vaccinated with live polio viruse

  • 40,00 cases of polio

  • 56 paralyzed

  • 5 deaths in family members

Cutter incident caused

reulatory changes

US government implimented much more vigilent monitoring and regulation of the vaccine industy