VACCINES:PAST, PRESENT, AND FUTURE

Starry Night or Deadly Virus?

Variola Virus

Smallpox signs and symptoms Fever Significant discomfort Headache Severe fatigue Severe back pain Vomiting Characteric rash Prognosis:

Fatality rate of ~33% Permanent and severe scarring Blindness can result

http://www.mayoclinic.org/diseases-conditions/smallpox/basics/complications/con-20022769

TRANSMISSION Airborne transmission – rapid spread Direct person-to-person contact Ventilation system Contact with infected items Potential: terrorist weapon In 2014— Forgotten vials of live variola virus at

the U.S. National Institutes of Health!

http://www.mayoclinic.org/diseases-conditions/smallpox/basics/complications/con-20022769

TREATMENT AND PREVENTION

No cure exists Antibiotic treatment for secondary infection

Vaccination- highly critical

http://www.mayoclinic.org/diseases-conditions/smallpox/basics/complications/con-20022769

Smallpox History

Smallpox may have been the cause of death for Rameses V3,200 year-old mummy

http://www.nature.com/news/infectious-diseases-smallpox-watch-1.15115

Smallpox History- Chinese vaccination, 1000 AD

http://www.historyofvaccines.org/content/timelines/smallpox

SMALLPOX HISTORY

1796: Edward Jenner, physician from the UK, demonstrated that those inoculated with cowpox had immunity to Variola virus

World’s first vaccine!

Nelson and Masters Williams, 2014

VACCINATION HISTORY

1885: Louis Pasteur developed rabies vaccine

1890: Antitoxins for diphtheria and tetanus were discovered by Emil von Behring and Shibasaburo Kitasato  

http://www.nhs.uk/conditions/vaccinations/pages/the-history-of-vaccination.aspx

VACCINATION HISTORY: ADVANCES IN 20TH CENTURY

  1920s: Wide availability of diphtheria, tetanus,

whooping cough, and tuberculosis vaccines 1955: Polio vaccine become available in UK 1966: WHO – Smallpox Eradication Programme 1980: Smallpox eradicated! 1965 – 2000: Significant reductions in child

mortality in sub-Saharan Africa, in part related to increased access to immunization

http://www.nhs.uk/conditions/vaccinations/pages/the-history-of-vaccination.aspxhttp://www.ncbi.nlm.nih.gov/books/NBK2296/

UNICEF State of the World’s Children Report, 2008

VACCINATION: SUCCESS AND FAILURE IN 20TH CENTURY

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UNICEF State of the World’s Children Report, 2008

GOALS OF VACCINATION CAMPAIGNS

Broad and continued coverage of immunizations among young children

Immunization schedule as early as possible WHO Expanded Program on Immunization:

Diphtheria, tetanus, pertussis, polio, measles mumps, and rubella (BCG and yellow fever in some cases)

Vaccinations in the US: Hepatitis B, diphtheria, tetanus, pertussis, Hib,

polio, measles, mumps, rubella and varicellaNelson and Masters Williams, 2014

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Immunization Schedule, Saudi Arabia

VACCINATION COVERAGE – U.S. EXAMPLE

U.S. vaccination coverage; 5 year olds, 2013 Median 2-dose MMR vaccination coverage was 94.7%

Range = 81.7% in Colorado to ≥99.7% in Mississippi 26 states and DC did not report meeting the Healthy

People 2020 target of 95% coverage for 2 doses Median DTaP vaccination coverage was 95.0%

Range = 80.9% in Colorado to ≥99.7% in Mississippihttp://www-ncbi-nlm-nih-gov.ezp-prod1.hul.harvard.edu/pubmed/25321068

http://www-ncbi-nlm-nih-gov.ezp-prod1.hul.harvard.edu/pubmed/25321068

VACCINATION COVERAGE – SAUDI ARABIA EXAMPLE

Saudi Arabia vaccination coverage for MMR (2004) Random selection of children ranging in age from

kindergarten through secondary school children who attended school or the well baby clinic

in Jeddah Coverage = 99% Variation was observed for prevalence of antibodies

http://www-ncbi-nlm-nih-gov.ezp-prod1.hul.harvard.edu/pubmed/16432596

http://www-ncbi-nlm-nih-gov.ezp-prod1.hul.harvard.edu/pubmed/16432596

VACCINATION STUDIES

Vaccine efficacy: randomized controlled trial Combination of vaccine efficacy and program

performance: observational studies Case-control Cohort Cross-sectional

Prevalence ratio = % protective antibody – vaccinated

% protective antibody – unvaccinated

Vaccine effectiveness (VE) = 1- Prevalence ratio (PR)

Nelson and Masters Williams, 2014

VACCINATION STUDIES

Observational studies- need to account for potential error, such as confounding

Potential confounders: age, sex, socioeconomic status, etc.

Nelson and Masters Williams, 2014

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Nelson and Masters Williams, 2014, p.295

Nelson and Masters Williams, 2014, p.295

GLOBAL POLIO ERADICATION INITIATIVE (GPEI)

WHO – eradicate polio by the year 2000 Challenges

3 serotypes exist, do not share cross-immunity Several doses of IPV or OPV are needed Factors related to low coverage:

Community resistance Difficulty in linking vaccine initiative to other

immunization programs Failure to engage high risk populations

Nelson and Masters Williams, 2014

BARRIERS TO POLIO ERADICATION

Failure to vaccinate – low coverage Vaccination failures

OPV – lower immunogenicity and effectiveness in tropical climates

Trivalent OPV – lower efficacy compared to monovalent vaccine

Nelson and Masters Williams, 2014

GPEI – MOVING FORWARD

A 99% reduction is not an option, according to the WHO: “As long as a single child remains infected, children in all countries are at risk of contracting polio”

2009/2010 – 23 previous polio free countries were reinfected due to import of polio virusNelson and Masters Williams, 2014, p.297

Nelson and Masters Williams, 2014, p.298

GROUP DISCUSSION

Based on your reading of Foege’s article on smallpox eradication, what are some strategies that can be used to eradicate polio?

Are there any strategies used in eradication of smallpox that may not be as useful in eradicating polio?

Are there additional concerns that need to be taken into account for polio that were not part of the smallpox eradication campaign?

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