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Discuss and identify the following: Brief summary of the article (2-3 sentences).What is the study design?What is the independent and dependent variables (aka “exposure” and “disease”)?Describe 4 biases that might need to be considered? (1 sentence each bias)Briefly describe what are the public health implications of this research(2-3 sentences) This assignment does NOT need to be in APA format and should be turned in as a WORD or PDF document. Please use the bullets above and headers for each section. The paper as a whole should be no more than 1-2 pages.

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Global child health
Julie Garon,1 Manish Patel2
Department of Infectious
Diseases, Emory University
School of Medicine, Atlanta,
Georgia, USA
Center for Vaccine Equity, Task
Force for Global Health, Decatur,
Georgia, USA
Correspondence to
Julie Garon, Department of
Infectious Diseases, Emory
University School of Medicine,
1462 Clifton Rd NE, Suite 446,
Atlanta, GA 30322, USA; julie.
Received 23 August 2016
Revised 21 December 2016
Accepted 26 December 2016
Published Online First
17 January 2017
The decades long effort to eradicate polio is nearing the
final stages and oral polio vaccine (OPV) is much to
thank for this success. As cases of wild poliovirus
continue to dwindle, cases of paralysis associated with
OPV itself have become a concern. As type-2 poliovirus
(one of three) has been certified eradicated and a large
proportion of OPV-related paralysis is caused by the
type-2 component of OPV, the World Health Assembly
endorsed the phased withdrawal of OPV and the
introduction of inactivated polio vaccine (IPV) into
routine immunisation schedules as a crucial step in the
polio endgame plan. The rapid pace of IPV scale-up and
uptake required adequate supply, planning, advocacy,
training and operational readiness. Similarly, the
synchronised switch from trivalent OPV (all three types)
to bivalent OPV (types 1 and 3) involved an
unprecedented level of global coordination and country
commitment. The important shift in vaccination policy
seen through global IPV introduction and OPV
withdrawal represents an historical milestone reached in
the polio eradication effort.
To cite: Garon J,
Patel M. Arch Dis Child
The world is closer to achieving complete eradication of polio than ever before. As of 4 January
2017, only 35 cases of wild poliovirus (WPV) have
been detected in 2016, compared with over
350 000 in 1988, the year when eradication effort
had begun (see figure 1).1 WPV type 1 is the only
wild-type strain (of types 1, 2 and 3) still in circulation. Oral polio vaccine (OPV) has largely been
responsible for much of this success particularly in
developing country settings due to its low cost,
ability to be administered without specialised training and ability to induce intestinal mucosal immunity and thus interrupt transmission within
populations in addition to protecting individuals.2
However, during replication in the gut of the vaccinee and subsequent chains of contact, the
live-attenuated vaccine virus undergoes evolution
through genetic reversions and possibly recombination with non-polio enterovirus C species. In very
rare cases, the vaccine virus may regain neurovirulence causing paralysis in recipients or close contacts (called vaccine-associated paralytic polio
(VAPP))2 and perhaps even acquire transmissibility
characteristics leading to outbreaks (circulating
vaccine-derived poliovirus (cVDPV)).2 Therefore,
to eradicate polio completely—both wild and
vaccine-derived viruses—the world must cease use
of OPV once WPV transmission has been interrupted (ie, polio endgame). After eradication,
immunity against polio will be provided by inactivated polio vaccine (IPV), an injectable vaccine that
does not cause VAPP or cVDPVs and induces an
response. However, compared with OPV, IPV is
costlier, provides lesser intestinal immunity and is
logistically more difficult to administer, particularly
when targeting hard to reach populations.3 In addition, IPV on its own does not appear to be sufficient
to halt poliovirus circulation and the risk of silent
transmission is likely to be greater in IPV-only
immunised populations, as occurred in Israel in
2013.4 As WPV cases continue to decrease, the
world is in the midst of an historical shift in vaccine
policy to ensure that no child is paralysed by polio
ever again. This paper provides an overview of the
polio endgame plan for paediatricians, infectious
disease specialists and the global health community.
To date, global polio eradication efforts have
included several general strategies leading to a dramatic reduction in the number of cases of WPV.
Including polio vaccines, OPV and more recently
IPV, into childhood routine immunisation schedules
has been the foundation of the global eradication
strategy. Active surveillance of children experiencing acute flaccid paralysis (AFP) including collection of stools followed by laboratory confirmation
of poliovirus is a bedrock of the polio programme
and has guided vaccination strategies. Ensuring
high routine immunisation coverage for polio and
other antigens has been an ongoing goal for vaccination programmes. Supplemental immunisation
activities (SIAs), in which all children under 5 years
of age are vaccinated in a mass campaign regardless
of vaccination status, have allowed more children
to be reached and reduced pockets of unimmunised
children. Periodic mop-up campaigns provide
further opportunities to vaccinate and serve to
increase immunity in at-risk areas.
To sustain the gains achieved so far and secure
final eradication of polio, partners of the Global
Polio Eradication Initiative (GPEI) launched the
Polio Eradication and Endgame Strategic Plan,
2013–2018, outlining detailed steps and a distinct
timeline for complete eradication of all types of
polio (both wild and vaccine derived).5 The four
objectives of the plan involve (1) completing eradication of WPV in its remaining strongholds; (2) a
phased, global transition from OPV to IPV while
strengthening routine immunisation systems; (3)
ensuring containment of poliovirus in laboratories
and facilities and (4) ensuring polio’s many
resources and lessons are used for other health priorities. This paper will focus mainly on the second
Garon J, Patel M. Arch Dis Child 2017;102:362–365. doi:10.1136/archdischild-2016-311171
Arch Dis Child: first published as 10.1136/archdischild-2016-311171 on 17 January 2017. Downloaded from on 23 June 2018 by guest. Protected by copyright.
The polio endgame: rationale behind the change
in immunisation
Global child health
objective of this plan, which includes introduction of IPV into
routine immunisation programmes in all OPV-using countries,
withdrawal of the type-2 component of OPV (ie, ‘the switch’)
and strengthening of routine immunisation systems.
OPV currently exists in five formulations: trivalent OPV (tOPV,
containing all three polio types), bivalent OPV (bOPV, containing types 1 and 3) and monovalent OPV (mOPV, containing
either types 1, 2 or 3). Surveillance has not detected any naturally occurring type-2 WPV since 1999 in Aligarh, northern
India and in September, 2015, the Global Polio Eradication
Certification Committee (GCC) certified the eradication of this
serotype.6 In addition, the type-2 component of tOPV (OPV2)
is associated with approximately 26%–31% of all VAPP cases
leading to 100–200 cases a year.7 Since 1999, it is estimated
from reports in the literature that anywhere from 1600 to 3200
people have experienced VAPP due to OPV2.8 OPV2 also plays
a significant role in cVDPV cases as 683 cases were reported
between 2000 and 2014, accounting for almost 90% of all
cVDPVs.9 Also, the type-2 component of tOPV interferes with
the immune response to types 1 and 3, and with type-1 WPV
still in circulation, maximum efficacy of the vaccine is
desired.2 10 For these reasons, the WHO Strategic Advisory
Group of Experts on immunisation (SAGE) deemed the risks of
tOPV to outweigh the benefits, necessitating the withdrawal of
the type-2 component of tOPV.
GPEI’s approach to OPV2 cessation has largely been about
risk reduction—reducing risks associated with ongoing use of
OPV and implementing measures to mitigate risks associated
with cessation of OPV. To minimise the risk of type-2 outbreaks,
GPEI considered a series of readiness criteria prior to the decision to proceed with the switch including eradicating type-2
WPV, stopping cVDPV2 outbreaks, introducing at least one dose
of IPV, licencing bOPV, containment of WPV2, ensuring high
type-2 immunity prior to the switch, stockpiling mOPV2 and
preparing a postswitch type-2 surveillance and outbreak
response protocol.11 Countries were advised by SAGE to
comply with a globally synchronised switch from tOPV to
bOPV in April, 2016, the month when poliovirus circulation is
at its lowest in endemic countries.11 12 Synchronising the switch
globally during a 2-week period reduced risks of cVDPV2 circulation or importation from an area with ongoing tOPV use to an
area where type-2 immunity was reduced due to discontinuation
of tOPV. Countries were to select 1 day (or several days for
some large countries) within the 2-week window to complete
the switch in all vaccine storage sites nationwide and validate
through site visits thereafter that all tOPV had been removed
from the cold chain. It was imperative that all countries stop
tOPV production and shipment, scale-up bOPV supply, procurement and shipment, and ensure country preparations globally
during the 6 months leading up to the switch.
Until eradication and containment are confirmed, and
perhaps even for some time after that point, some immunity
against polioviruses will be necessary. Thus, IPV (which contains
all three poliovirus types) is to provide some level of immunity
to type 2 following OPV2 withdrawal. In 2014, WHO recommended that all 126 OPV-using countries introduce at least one
dose of IPV intro routine immunisation schedules.13 As of
November, 2016, 173 (89%) of 194 WHO member states were
using at least one dose of IPV and the remaining countries have
committed to introducing as soon as sufficient supply is available, likely in 2017.14 One dose of IPV leads to lower seroconversion rates (19%–46% against type 1, 32%–63% against type
2 and 28%–54% against type 3)15 than three or four doses,
which provides nearly complete protection. However, data indicate nearly all children are ‘primed’ after one dose of IPV; that
is, those who do not seroconvert after one dose of IPV may
mount a rapid immune response within 7 days of subsequent
exposure and thus theoretically could be protected against paralysis if exposed to poliovirus.16 Routine IPV administration
may also facilitate interruption of transmission during cVDPV2
outbreaks through use of mOPV2 (stockpiled for posteradication type-2 outbreaks) as the population immunity may already
be closer to herd immunity thresholds.10 IPV has also been
shown to reduce duration and amount of viral shedding.15 17
IPV may aid in eradicating WPV by boosting immunity to types
1 and 3 polioviruses in individuals who have received bOPV or
tOPV.10 11
Several additional factors warrant consideration for IPV. IPV
also induces mucosal immunity but to a lesser extent than OPV,
particularly with regard to intestinal immunity in developing
country settings, where the faecal–oral route is the predominant
mode of transmission.17 Studies of intradermal administration of
fractional doses (1/5 of a full dose) of IPV found that two doses
resulted in much higher seroconversion (98% in Cuba and 81%
in Bangladesh) to type-2 poliovirus than one full dose (63% in
Cuba and 39% in Bangladesh).16 18 19 For this reason, WHO
has also endorsed the use of two fractional doses of IPV at 6 and
14 weeks for countries conserving limited vaccine supply, given
the programmatic cost and logistical implications of intradermal
administration (additional supplies and health worker training
needed for intradermal administration) is considered.19 IPV also
Garon J, Patel M. Arch Dis Child 2017;102:362–365. doi:10.1136/archdischild-2016-311171
Arch Dis Child: first published as 10.1136/archdischild-2016-311171 on 17 January 2017. Downloaded from on 23 June 2018 by guest. Protected by copyright.
Figure 1 Progress in polio
eradication from 1988 to 2016 (*as of
4 January 2017). (Data from The
Global Polio Eradication Initiative. Data
and Monitoring. 2016. http://
(accessed 6 January 2016).
Global child health
Introduction of IPV in 126 OPV-only using countries within a
matter of a few years was an unprecedented and daunting task.
To facilitate country buy-in, GPEI partners and supporting agencies developed advocacy tools such as policy papers, guidelines,
case studies and information packets to communicate the complicated technical rationale behind IPV introduction to stakeholders.14 Detailed planning documents and templates were
developed for adaptation and use in country. Specialised workshops took place in various locations worldwide to further raise
awareness, share tools, support development of country introduction plans and assess planning progress. In-country missions
from GPEI partners and trained consultants provided technical
support and facilitated in the completion of IPV introduction
Countries exhibited an exemplary level of commitment to the
introduction of IPV, with all countries either introducing at least
one dose of IPV in 2015 or committing to introduce IPV prior
to the switch. However, despite long-term agreements with two
IPV manufacturers to meet increased demand, manufacturers
encountered setbacks and challenges due to the rapid scale-up
of complex production processes, leading to supply constraints
globally. GPEI prioritised use of IPV in SIAs, stockpiling for outbreak response, and introductions in countries at high risk for
polio. As of 7 November 2016, 173 countries (89% of the
global birth cohort), including those at the highest risk of polio,
have introduced IPV into routine immunisation schedules.14
Twenty countries (10% of the global birth cohort) delayed introduction until 2017 due to supply constraints. After careful
evaluation of context-specific risks and implications, countries
adapted to the situation through delayed or phased introductions, or consideration of a two-dose series of intradermal fractional administration of IPV, as recommended by SAGE.
In October, 2015, SAGE reviewed global epidemiological data
for polio and the readiness criteria for the switch and confirmed
17 April to 1 May 2016 as the official dates during which all
countries would switch from tOPV to bOPV.26 Similar to IPV
introduction, extensive global-level, regional-level and countrylevel advocacy was required far in advance of these dates to
ensure buy-in from country governments and partners. To facilitate this complex endeavour, GPEI partners developed and disseminated guidance documents and toolkits, held workshops
and provided the necessary technical assistance and resources to
countries before the switch. Guidelines for planning for the
switch revolved around four key steps: planning, preparation,
implementation and validation. Planning ensured that all countries established appropriate management/coordination mechanisms and secured adequate financing for switch activities.
Countries conducted frequent tOPV vaccine inventories to
inform vaccine forecasting, limit excess tOPV requiring disposal
after the switch and avoid stock outs prior to the switch.
Preparation activities included planning vaccine transport, collection and disposal, training of health workers and logisticians
and developing communication strategies. On the day of the
switch, all tOPV would be removed from the cold chain and
placed in a designated area for disposal by appropriate means
such as boiling, incineration, chemical inactivation, autoclaving
or encapsulation. Finally, independent monitors would visit all
vaccine distribution stores in the country as well as a sample of
the fixed health facilities where vaccine is administered to
ensure tOPV had been removed from the cold chain.
Independent validation committees reviewed these data and provided confirmation of adequate tOPV withdrawal and/or recommendations for corrective actions needed by national
authorities. WHO confirmed that by mid-May, 2016, all 155
OPV-using countries successfully discontinued use of tOPV.
Despite momentous recent achievements, the endgame is not
without risks of re-emergence of cVDPV2 and WPV2. Risk of
cVDPV2 emergence is greatest in the first 6–12 months after the
switch due to the expected decline in humoral and intestinal
immunity against type-2 poliovirus after OPV2 withdrawal even
with the introduction of one dose of IPV.27 Longer term risks
include reintroduction of type-2 poliovirus from a laboratory or
manufacturing facility breach, as occurred in 2002–2003 in
India.28 In addition, a risk exists that populations could be
exposed to poliovirus through B-cell immune deficient individuals, who are known to have a higher risk or prolonged poliovirus excretion.29
Outbreak control protocols have been prepared and a large
stockpile of mOPV2 is available, should an outbreak of wild or
vaccine-derived polio be detected. Maintenance of strong AFP
surveillance and utilization of targeted environmental surveillance will become increasingly important after eradication.
Implementation of a comprehensive strategy to ensure containment of poliovirus, prioritising type-2 poliovirus, is currently
underway.30 Two drug candidates for treatment of B-cell
immune-deficient long-term excreters are in late-stage clinical
trials with promising results in reduction of shedding among
participants.31 Finally, numerous tools and technologies capable
of making IPV production safer and development of stable OPV
with less risk of reversion to infective virus are also being
explored.10 32
All OPV is expected to be withdrawn after 2020, similarly to
the 2016 switch, if transmission of type-1 WPV can be interrupted in Pakistan, Afghanistan and Nigeria in the coming year.
Once all countries and regions have been certified polio free,
Garon J, Patel M. Arch Dis Child 2017;102:362–365. doi:10.1136/archdischild-2016-311171
Arch Dis Child: first published as 10.1136/archdischild-2016-311171 on 17 January 2017. Downloaded from on 23 June 2018 by guest. Protected by copyright.
has additional benefits when used during posteradication outbreaks of not reintroducing type-2 vaccine virus into the population, which is a concern when the live vaccine mOPV2 is used
alone. Children having already received OPV will receive a boost
in humoral and intestinal immunity after an additional dose of
IPV, thus helping to interrupt transmission.20
While both the accelerated introduction of IPV globally and
the synchronised switch from tOPV to bOPV are unprecedented
in terms of timeframe, size and scope, many countries have
experienced transitions in polio vaccines in the past. Most industrialised countries no longer experiencing WPV transmission transitioned to IPV-only schedules many years ago out of concern for
VAPP and cVDPV’s. Some switched over at once, while others
transitioned through a period of sequential use of OPV and IPV.
For example, the USA transitioned to a sequential schedule of
two doses of IPV followed by two doses of OPV in 1997, followed by a transition to all-IPV in 2000.21–23 Many countries are
familiar with the use of bOPV in campaigns and with using different OPV formulations depending on global epidemiology of
WPV. In India, transmission persisted in the underdeveloped and
highly populated states of Bihar and Uttar Pradesh despite high
coverage and multiple doses of vaccine, leading to the development of mOPV1, mOPV3 and bOPV, which had much higher efficacy per dose than tOPV.24 Use of these new vaccines in SIAs
were innovations contributing to the elimination of polio in
India, a monumental achievement …
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