VACCINES: PAST, PRESENT, AND FUTURE. Starry Night or Deadly Virus?
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Transcript of VACCINES: PAST, PRESENT, AND FUTURE. Starry Night or Deadly Virus?
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
Nelson and Masters Williams, 2014, p.273
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
Nelson and Masters Williams, 2014, p.281
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
Nelson and Masters Williams, 2014, p.289
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?
Nelson and Masters Williams, 2014, p.297