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Learning Objectives
Describe which characteristics of a disease may help make a campaign to eradicate it successful (or unsuccessful)
Understand vaccine/immunization campaigns works at the individual and population levels, and the main tools/strategies used in such campaigns.
Compare and contrast the characteristics of smallpox, malaria, and polio. Based on these characteristics, explain the differences between the immunization and/or eradication campaigns associated with each of these diseases.
Explain the unintended consequences on global public health of the CIA’s raid on the Bin Laden compound
Know what the term herd immunity means
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Which of the following is NOT an example of a ‘vertical’ public health program?
The eradication of smallpox through vaccination
Spraying DDT to decrease the breeding of the Anopheles mosquitos which are the vector for malaria
An initiative to use DOTS (Directly Observed Treatment, Short-course) to treat all cases of tuberculosis
Training community health workers to identify and treat common health problems and to refer individuals with more complex health problems to visit a clinic
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Reminder: Colonialism’s legacies for global health
Investing in “vertical” programs, not in health systems
Targeting specific infectious (“tropical”) diseases not chronic diseases
Method was through technical fixes (vs. addressing social/economic roots of health problems)
Top-down decision making without the participation of locals (vs. locals having decision making power)
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Wealth
Health
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Wealth
Health
What are the benefits of a vertical campaign at:
Individual level?
National/population level?
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What have you been immunized for? What might be missing?
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How do vaccination campaigns work?
Individual level
Trigger immune response to infectious agent
Individual responses vary and some people cannot be immunized
Population level
Herd immunity
When very few people are able to carry a disease the virus cannot find a host and therefore cannot spread in that population
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Herd immunity
Good animation that demonstrates herd immunity:
https ://www.youtube.com/watch?time_continue=154&v=CPcC4oGB_o8&feature= emb_logo
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Source: https ://theconversation.com/what-is-herd-immunity-and-how-many-people-need-to-be-vaccinated-to-protect-a-community-116355
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Feb 2019 measles Outbreak in Portland, OR and Washington state
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Boulder periodically has very high rates of pertussis due to people choosing not to vaccinate their kids. Not getting to herd immunity levels necessary to keep the diseases at bay.
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Expanded Programme on Immunization (EPI)
Introduced by WHO in 1974
Primary Goal: immunize all children under 5 by 1990 to 6 vaccine-preventable diseases
Secondary Goal: promote countries delivering immunizations themselves within their own comprehensive health services to strengthen overall health infrastructure
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Number of countries that reached and sustained 90% coverage with 3 doses of DTP-containing vaccines since 2000, and global DTP3 coverage (as of 2017)
Example of where we are globally with immunization: explain DPT. DTP = diptheria, tetanus, and pertussis (which is whooping cough).
Explain the difference between the lines and the columns. [CR: the line represents global population. # of countries is going up, but smaller countries are being added so the total % coverage is not being impacted as much]
Show this animation: https://www.who.int/immunization/monitoring_surveillance/data/coverage_dorling_dtp1_animation.gif?ua=1
Source: WHO/UNICEF coverage estimates 2017 revision,. July 2018. United Nations, Population Division. The World Population Prospects - the 2017 revision". New York, 2017
Immunization Vaccines and Biologicals, (IVB), World Health Organization.
194 WHO Member States. Date of slide: 15 July 2018.
Time series animation of DTP1 global coverage:
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2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 62.0 66.0 68.0 69.0 72.0 80.0 84.0 87.0 87.0 91.0 97.0 99.0 102.0 105.0 108.0 113.0 117.0 123.0 countries < 90%
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 129.0 125.0 124.0 123.0 120.0 112.0 109.0 106.0 106.0 102.0 96.0 95.0 92.0 89.0 86.0 81.0 77.0 71.0 DTP3 coverage
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 72.0 73.0 73.0 74.0 76.0 77.0 79.0 79.0 81.0 83.0 84.0 85.0 84.0 84.0 84.0 85.0 85.0 85.0
Number of countries
Coverage (%)
Time series of DTP vaccination globally
https://www.who.int/immunization/monitoring_surveillance/data/coverage_dorling_dtp1_animation.gif?ua= 1
Coverage = % of people in a country vaccinated
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| My country: Kyrgyzstan, 2019 | My region: European Region, 2019 | |
| DTP3 (Diptheria, Tetanus, Pertussis, 3 doses) | 95% | 95% |
| MCV2 (Measles, 2 doses) If no data reported for MCV2, report MCV1 | 99% | 91% |
| Pol3 (Polio, 3 doses) | 97% | 95% |
Mini-research exercise:
What are the immunization rates for your country?
Find the averages for your region here: https://www.who.int/immunization/monitoring_surveillance/data/en/
Under #1, click on the appropriate world region. Select regional profile
Find your country’s estimates here:http ://apps.who.int/immunization_monitoring/globalsummary
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New developments on the vaccine front
2019 malaria vaccine for kids in sub-Saharan Africa
2018 Investigational vaccine for Ebola used in outbreak areas (awaiting further research)
2019 A second vaccine for Ebola to be used in the Democratic Republic of Congo
And of course Covid-19….
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Eradication Campaigns
Most (but not all) eradication campaigns are ‘vertical’ and rely on a ‘technical’ fix
Eradication Campaign
Smallpox
Malaria
Yaws
Polio
Guinea Worm
Technical Fix?
Yes – vaccine
Yes – insecticides
Yes – injectable long-acting antibiotic
Yes – vaccine
No – mostly behavior change, cloth/nylon filtration, deep well digging, some larvicide
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| Disease Characteristics | Smallpox | Malaria |
| Transmission | Direct human-to-human contact | |
| Recurrence | Permanent immunity from a single infection or vaccination | |
| Latency | Short and known latency period (7-14 days) | |
| Case identification | Infection is obvious – distinctive rash | |
| Prevention | Vaccine extremely effective and didn’t require a cold chain |
Adapted from Table 3.1 in Farmer et al. Reimagining Global Health
How do we know if an eradication program will be successful?
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How do we know if an eradication program will be successful?
| Disease Characteristics | Smallpox | Malaria |
| Transmission | Direct human-to-human contact | Vector-borne (via Anopheles mosquitos) |
| Recurrence | Permanent immunity from a single infection or vaccination | No immunity with previous infection |
| Latency | Short and known latency period (7-14 days) | Can remain in the body for many months without symptoms |
| Case identification | Infection is obvious – distinctive rash | Symptoms can resemble other diseases |
| Prevention | Vaccine extremely effective and didn’t require a cold chain | Target the mosquitos (e.g. kill them with DDT) or deal with the parasite (e.g. with chemoprophylaxis). No vaccine yet. |
Adapted from Table 3.1 in Farmer et al. Reimagining Global Health
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Which of the following conditions would make a disease easier to eradicate by vaccination?
There is an animal that can be infected with the disease and a vector that can transmit the disease from the animal to humans
The symptoms of the disease resemble flu-like conditions
The time from infection to onset of symptoms can be many years
Infection with the disease leads to immunity after recovery
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Now: Polio A Polio Volunteer’s Story (Sudan)
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Polio Eradication Progress, 1988 – 2018
Certified polio-free regions (126 countries)
Endemic with wild poliovirus (3 countries)
Not certified but non-endemic (65 countries)
Source: WHO/POLIO database, as of July 2018.
194 WHO Member States.
The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. © WHO 2018. All rights reserved.
World Health Organization
13 February 2022
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Polio
Viral
75% no symptoms
24% flu-like symptoms
1% flaccid paralysis, which can be permanent
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| Disease Characteristics | Smallpox | Malaria | Polio |
| Transmission | Direct human-to-human contact | Vector-borne (via Anopheles mosquitos) | Fecal/oral and respiratory droplets |
| Recurrence | Permanent immunity from a single infection or vaccination | No immunity with previous infection | 25-40% have “post-polio syndrome” – onset is decades after polio onset |
| Latency | Short and known latency period (7-14 days) | Long (Can remain in the body for many months without symptoms) | average 7-10 days (range 4-35 days) |
| Case identification | Infection is obvious – distinctive rash | Symptoms can resemble other diseases; asymptomatic carriers likely due to latency period. | What do you think? |
| Prevention | Vaccine extremely effective and didn’t require a cold chain | Either kill the mosquito with DDT or deal with the parasite with chemoprophylaxis. No vaccine yet. | Oral vaccine, needs multiple doses, requires cold chain. |
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Eradication strategies: Smallpox vs. Polio
Smallpox eradication strategy:
Surveillance: A system that tracks diseases in a population (Who has it, where are they? Who have they come into contact with?)
Containment: Selectively vaccinating people who had been in contact with an infected person
Polio eradication strategy:
If polio causes paralysis in 1% of people and is spread by respiratory droplets and contaminated feces, how would you create a surveillance plan?
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Polio Surveillance: Method 1
1. Nation-wide Acute Flaccid Paralysis (AFP) surveillance
reporting children with acute flaccid paralysis (AFP)
Sending stool samples
ID’ing in lab
mapping the virus to determine the origin of the virus strain
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Polio Surveillance: Method 2
2. Environmental surveillance
Testing sewage for the presence of poliovirus.
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In addition to surveillance, need:
Target of 100% immunization - had to vaccinate EVERYONE
National Immunization Days
“mop-up campaigns”
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How could the polio eradication campaign improve overall health systems?
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Other aspects necessary for successful global health campaigns
Coordination among numerous organizations
Government (both national and local), international, and non-governmental organizations
Political will
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To be sure…
Vertical campaigns have advantages and disadvantages
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The CIA, Polio Vaccines and Osama Bin Laden: Unintended Consequences
What does the capture of Osama Bin Laden have to do with Pakistan’s polio campaign?
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Letter from Deans of Schools of Public Health to President Obama
“While political and security agendas may by necessity induce collateral damage, we as a society set boundaries on these damages, and we believe this sham vaccination campaign exceeded those boundaries.”
“…contaminating humanitarian and public health programs with covert activities threatens the present participants and future potential of much of what we undertake internationally to improve health and provide humanitarian assistance.”
“International public health work builds peace”
“As public health academic leaders, we hereby urge you to assure the public that this type of practice will not be repeated.”
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From the White House
Summary: Vertical initiatives
Focused on a single disease
Normally top-down in design
Historically have emphasized technological fixes
BUT guinea worm eradication effort is an important exception to this
An eradication campaign is a vertical initiative, but vertical initiatives are not necessarily eradication campaigns
And many immunization campaigns did not intend to eradicate, e.g. Efforts to decrease incidence of HIV and treat HIV infection
Often include measures of baseline prevalence or incidence of the disease, and measures them again post-intervention (uses surveillance to measure efficacy)
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