Questions and Answers on Polio
Q What is poliomyelitis?
Poliomyelitis (polio) is a highly infectious
disease caused by a virus that invades the nervous system
and can cause total paralysis in a matter of hours. Approximately
one in 200 infections leads to irreversible paralysis,
usually in the legs. Among those paralysed, five to ten
per cent die when their breathing muscles become immobilized.
Poliomyelitis mainly affects children under 5 years of
Q How is it transmitted?
The virus enters the body through the mouth and multiplies
in the intestine. It invades the nervous system and can
cause total paralysis in a matter of hours.
Q How can poliomyelitis be treated?
There is no cure for poliomyelitis, but it can be
prevented. Polio vaccine, given multiple times, can protect
a child for life.
Global Polio Eradication Initiative
Q What is eradication?
Eradication of poliomyelitis is defined as ending the
transmission of the wild poliovirus, meaning that no children
will be paralysed by the wild poliovirus.
Q Why eradicate poliomyelitis?
Poliomyelitis is one of the few diseases that can be
eradicated because it cannot survive long outside the
human body, and an inexpensive and effective immunization
mechanism, oral polio vaccine (OPV), is available.
The humanitarian impact of eradicating poliomyelitis
is enormous - by 2005 five million children in the developing
world who would have been paralysed will be walking because
they have been immunized against poliomyelitis. Polio
eradication is a global public good - something from which
all people can benefit for all time.
Q Have any other diseases been eradicated?
Yes, smallpox has been eradicated. WHO launched the
smallpox eradication programme in 1967. At that time,
some 10-15 million cases of smallpox were occurring each
year. In 1980, the disease was certified as eradicated.
Q What is the Global Polio Eradication Initiative?
The global effort to eradicate polio is the largest
public health initiative in history. The initiative was
launched in 1988 by the Forty-first World Health Assembly
with the goals of eradicating polio while strengthening
capacity to control other major childhood diseases. This
followed significant progress towards elimination of the
poliovirus in the Americas, as well as Rotary International's
commitment to raise funds for poliomyelitis eradication.
Extraordinary progress has been made towards achieving
a polio-free world by 2005.
Q Who is involved in the Global Polio Eradication
The Initiative is spearheaded by WHO, Rotary International,
the US Centers for Disease Control and Prevention (CDC)
and the United Nations Children's Fund (UNICEF).
The polio eradication coalition includes: the governments
of countries affected by poliomyelitis; private foundations
such as the United Nations Foundation and Bill & Melinda
Gates Foundation; development banks such as the World
Bank; donor governments such as Australia, Austria, Belgium,
Canada, Denmark, Finland, Germany, Ireland, Italy, Japan,
Luxembourg, Netherlands, Norway, United Kingdom and United
States of America; the European Commission; non-governmental
organizations; humanitarian organizations such as the
International Red Cross and Red Crescent societies; and
corporate partners such as Aventis Pasteur and De Beers.
Volunteers and health workers in developing countries
also play a key role: 10 million have participated in
mass immunization campaigns.
Q What are the strategies for eradicating polio?
The four key strategies for eradicating poliomyelitis
1) routine immunization of infants with OPV in the first
year of life;
2) supplementary immunisation activities, national immunization
days and sub-national immunisation days (NIDs and SNIDs),
during which all children under five years of age are
vaccinated, regardless of whether they have been vaccinated
3) mop-up campaigns, to ensure that every child is vaccinated
and to break the final chains of transmission; and
4) effective disease surveillance for acute flaccid
paralysis (AFP) to find and investigate every newly paralysed
child to determine if poliomyelitis is the cause of the
Q Which vaccine is recommended for polio eradication?
Oral polio vaccine is safe, effective, inexpensive,
and the recommended vaccine for the global effort to eradicate
poliomyelitis. Because of its high levels of immunity,
especially in the intestines, it is the only vaccine proven
to stop transmission of the virus in developing countries.
OPV is easy to deliver. It drops from a vial into the
mouth of the child and can be administered by volunteers
as well as trained health workers.
Status of the Global Polio Eradication Initiative
Q What has been achieved globally?
The Global Polio Eradication Initiative has made tremendous
progress toward its goal. Two of the six WHO regions have
been certified as polio-free (the Americas and the Western
Pacific regions) and the European Region could be certified
on 21 June 2002.
In the remaining WHO regions significant progress continues
to be made. As of 10 June 2002 480 cases were reported
globally in 2001, representing a 99.8% decline in the
number of cases since the initiative began in 1988, when
350 000 cases were estimated to occur each year. In the
same time period, the number of polio-endemic countries
dropped from 125 to just 10.
Q Which countries still have poliomyelitis?
The remaining polio-endemic countries are Afghanistan,
Angola, Egypt, Ethiopia, India, Niger, Nigeria, Pakistan,
Somalia, and Sudan. Five of the ten countries accounted
for 96% of all new cases in 2001 and are considered the
high-transmission areas. They are Northern India, Pakistan/Afghanistan
The remaining countries can be grouped into areas of low
transmission. They are Somalia/Sudan/Ethiopia, Angola
Q When will the transmission of wild poliovirus be
Countries in the low transmission areas can stop transmission
by mid-2002 provided all children under five are reached
during the NIDs and there is no deterioration of security.
The countries in high transmission zones - India, Pakistan,
Afghanistan, Nigeria and Niger - are aiming to stop transmission
by the end of the year. A review of progress in these
countries will be undertaken late in the year to determine
whether there is some risk of continuing transmission
Q Which areas pose the greatest risk to the goal of
interrupting transmission by the end of 2002?
The global Technical Consultative Group on poliomyelitis
eradication (TCG) determined that India, Pakistan and
Nigeria pose the greatest risk to the target date, due
to continued high-intensity transmission, high population
density, and low routine immunization coverage. However,
these three countries have made tremendous progress towards
eradication and are recording cases in smaller and smaller
areas, indicating that transmission is increasingly confined
to certain geographical areas, despite certification-standard
Q What is the impact of the events of 11 September
on the programme, especially as Afghanistan is in one
of the high-transmission zones?
Afghanistan continued to make progress towards poliomyelitis
eradication, despite the events of 11 September. The country
conducted two rounds of NIDs in September and November
and reached most of the children targeted. Another NID
was conducted in April 2002 and was carefully coordinated
with Pakistan to ensure good coverage in the border areas.
The impact on the eradication programme included disruption
of some activities on the ground and a deterioration of
the surveillance system. A priority for the program is
to re-establish certification-standard surveillance as
soon as possible. The long-term impact could include a
lull in financing, as donors' priorities shift.
Q What does certification mean?
- Certification is the process that verifies that a
region, and eventually the entire world, are polio-free.
Two of the six WHO regions have been certified as polio-free:
the Americas in 1994 and the Western Pacific Region
in 2000. The European Region is on track for certification
in June 2002.
- A formal certification process is in place for all
WHO regions of the world. Before a region can be certified
polio-free, several conditions must be satisfied:
- at least three years of zero confirmed cases due
to indigenous circulation of wild poliovirus;
- excellent laboratory-based surveillance for poliovirus;
- demonstrated capacity to detect, report, and respond
to imported cases of poliomyelitis; and
- assurance of safe containment of poliovirus in laboratories
(introduced since 2000).
Q Will the world be ready for global polio-free certification
The global initiative is on track for certification in
2005. Intensified immunization activities and certification-standard
surveillance, with efforts to overcome remaining challenges
to the programme (access to all children, maintaining
political commitment and closing the US$ 275 million funding
gap) could result in polio-free certification in 2005.
Status of the WHO European Region
Q What was the status of transmission of poliovirus
when the eradication initiative began in the European
The thirty-ninth session of the Regional Committee endorsed
the target of regional poliomyelitis elimination by 2000
in September 1990. By 1990 significant progress had already
been made in controlling poliomyelitis throughout much
of Europe and it appeared that 32 countries had interrupted
transmission. However, transmission of wild poliovirus
remained intense in the central Asian republics, Caucasus
republics and Turkey with 354 cases reported from 14 countries.
Q How was transmission of wild poliovirus stopped
in the European Region?
There were numerous challenges to achieving the goal
of interrupting transmission of wild poliovirus in such
a large, geographically and demographically diverse region.
The social and economic changes following the dissolution
of the USSR and redefinition of national borders in south
central Europe impacted the programme with delivery of
immunization services and vaccine supply being disrupted
in many parts of the region.
The partnership supporting the eradication programme was
greatly strengthened during this transition. Numerous
partners and bilateral agencies worked to strengthen routine
immunization by stabilizing the vaccine supply, at the
same time laying the groundwork for countries to conduct
NIDs. Surveillance systems were strengthened, providing
detailed information on where transmission was occurring
and among which populations. Surveillance data was critical
to guide end-stage activities, such as mop-ups, to areas
with remaining transmission of wild poliovirus.
Large outbreaks occurred in the early 1990s. The epidemiological
situation indicated that interrupting transmission in
a large geographical area would require high immunization
coverage and effective cross border surveillance. Operation
MECACAR was introduced with this purpose in 1995, organizing
synchronized NIDs across 18 countries in the European
and Eastern Mediterranean Regions, and successfully interrupted
transmission of wild poliovirus in large geographic areas.
Surveillance provided valuable information guiding end-stage
mop-up campaigns in areas where transmission persisted.
This surveillance data identified a reservoir of poliovirus
transmission in Turkey, from which 26 cases were detected
in 1998, shared with northern Iraq. Intensive mop-up immunization
activities were conducted, apparently stopping transmission
of wild poliovirus as the last reported cases of poliomyelitis
in the Region due to indigenous wild poliovirus has onset
of paralysis on 26 November 1998.
Q What is Operation MECACAR?
Operation MECACAR is an unprecedented coordinated polio
eradication effort across 18 countries and areas in the
Mediterranean, Caucasus and Central Asia. This initiative
synchronized NIDs in 10 MECACAR countries European Region
(Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgystan,
Russian Federation, Tajikistan, Turkey, Turkmenistan and
Uzbekistan) as well as with 8 neighbouring countries in
the Eastern Mediterranean Region. Operation MECACAR achieved
92% coverage reaching up to 60 million children for vaccination
and appeared to have interrupted transmission of wild
poliovirus in large geographic areas.
After the success of the initiative, 'Operation MECACAR
Plus', continued collaboration of the MECACAR countries
was started in 1998.
Q What is the status of polio-free certification of
the European Region?
The last identified indigenous poliovirus case in Europe
was in Melik Minas, who was 33 months old when he was
paralysed by poliomyelitis in South Eastern Turkey on
26 November 1998. He had never been vaccinated against
poliomyelitis. In November 2001, the WHO European Region
marked three years of being free of confirmed indigenous
As no indigenous wild poliovirus has been isolated under
conditions of certification-standard surveillance in any
member state of the WHO European Region since November
1998, the region is on track for certification when the
WHO European Regional Commission for Certification of
Poliomyelitis Eradication meets on 21 June 2002.
Q What is the Regional Certification Commission?
The European Regional Certification Commission is an
independent panel of eight experts in public health, epidemiology,
virology, and clinical medicine. The Commission was established
in March 1996.
Q How will the Commission determine whether to certify
the European Region polio-free?
The Certification Commission has the responsibility
to review data and background for all Member States to
determine whether or not there is sufficient evidence
that transmission of wild poliovirus has been interrupted.
The Commission has been reviewing country specific documentation
since 1999. Specific issues being addressed by the Commission
- reassessment of the sensitivity and promptness of
the surveillance systems;
- commitment from all Member States to continue surveillance
and high levels of immunization - with particular attention
to vulnerable subpopulations;
- indications that wild poliovirus imported from outside
the Region has not become established in transmission
within Europe, especially in Georgia; and
- documentation that substantial progress has been
made by all countries towards identifying those laboratories
holding wild poliovirus or potentially infectious material
in a containment process that will ensure appropriate
bio-safety holding measures.
Q What are the current challenges to certification
for the European Region?
When the Regional Certification Commission met in March
2002, more than three years after the last reported case
of indigenous poliomyelitis in the region, its members
identified areas requiring additional documentation or
action. These include the provision of additional documentation
on the interruption of transmission of a wild poliovirus
importation into Georgia and Bulgaria from south Asia
in mid-2001, national plans for continuing immunization
and surveillance activities through global certification,
and survey and inventory of facilities holding wild poliovirus
stocks or potentially infectious materials according to
agreed timelines. The RCC will be reviewing the status
of each of these areas at its meeting in June.
Q What is an importation?
Importation occurs when a poliovirus is introduced into
an area in which it did not previously circulate. An importation
can result in virus transmission being re-established
in an area that is considered polio-free, if the importation
is not detected and responded to quickly.
All countries remain at risk of importations until transmission
of wild poliovirus is interrupted globally, demonstrating
the fragility of any area's polio-free status. High immunization
coverage is required to prevent an imported virus from
finding an under-immunized, susceptible population in
which transmission can continue. A sensitive surveillance
system, able to quickly detect and identify any importation
and guide a programmatic response, is critical. The WHO
European Region detected two importations, to Bulgaria
and Georgia, in 2001 alone.
Q How do imported cases of poliomyelitis affect the
The global TCG has determined that when an importation
is identified, targeted immunization must take place immediately
to prevent further infection, followed by careful surveillance.
Importation of poliovirus does not affect certification
status as long as it is dealt with promptly and appropriately
and does not re-establish prolonged or extensive circulation
of the virus.
Q How does the outbreak in Bulgaria affect certification
of the European Region?
The outbreak in Bulgaria early in 2001 was caused by
a Type-1 wild poliovirus imported from the Indian sub-continent.
The outbreak caused 3 cases of paralysis from March to
May, and affected children in the Roma community - a traditionally
under-immunized population. The government of Bulgaria
responded very quickly to stop the outbreak, by conducting
sub-NIDs in April followed by NIDs in May and June. Surveillance
has been enhanced to ensure there are no additional cases.
The WHO European Regional Office approached all countries
of central and southern Europe with high-risk subpopulations,
such as refugees and immigrants. Countries were encouraged
to review the vaccination status of high-risk populations,
strengthen surveillance and take additional action as
necessary. The size of response actions taken by countries
varied in scale.
As the outbreak was contained within months of the index
case, the Commission has stated that the regional certification
timeline will not be affected. The WHO European Region
remains on track for certification in June 2002.
Q What happened in Georgia and what has been the response?
In December 2001, a wild poliovirus was isolated from
a 5-year-old boy who had symptoms of meningitis/encephalitis
with onset from September. Type-1 wild poliovirus was
isolated, closely resembling viruses currently circulating
in the Indian sub-continent. The child was diagnosed with
Following local immunization of children and enhanced
surveillance, two rounds of NIDs were conducted in March/April
and April/May 2002. Armenia and Azerbaijan conducted mass
immunization campaigns in the appropriate bordering territories.
The Commission will be reviewing additional documentation
on the interruption of transmission of the imported wild
poliovirus in Georgia prior to making its decision on
European certification in June.
Q What poliomyelitis eradication activities will be
continued in the European Region after certification and
The Regional Certification Commission will continue
to meet yearly for updates on polio eradication activities
in the Region. All countries will need to maintain high
immunization coverage, paying special attention to vulnerable
subpopulations, and to sustain high quality laboratory
based surveillance through global certification. Recent
experiences with importations into the region have highlighted
Countries will need to implement activities to survey
laboratories that may have stocks of wild poliovirus and
ensure laboratory containment of wild polioviruses, preparing
for global eradication by limiting reservoirs of virus.
Q What happens if a case of poliomyelitis is imported
into Europe after certification?
An immediate response with supplemental immunization
would be required, similar to the prompt action taken
in response to the importations into Bulgaria and Georgia,
discussed earlier. The objective of the immunization activities
would be to ensure that imported virus is not allowed
to establish transmission locally.
A report would be required by the Regional Certification
Commission detailing the action taken and evidence that
the importation was controlled - meaning that there was
no transmission more than six months after the importation,
followed by a final report one year after the importation.
The Commission has asked each country to provide a plan
of action for this circumstance in advance of the certification
Looking forward - Global Programme
Q What are the major challenges to poliomyelitis eradication?
The remaining global priorities for poliomyelitis eradication
1) close the US$275 million funding gap, the single
greatest threat to the eradication initiative;
2) secure access to all children, especially in
areas of conflict;
3) maintain political commitment in the face of
a disappearing disease; and
4) implement the endgame strategies to: ensure
that wild poliovirus is securely contained in laboratories,
maintain certification-standard surveillance, and develop
post-certification immunization policy.
Q What is the funding gap and what is being done to
The total external financial support needed through 2005
- the target date for certification-is US $1 billion.
US $725 million has been pledged to date. This leaves
a financial shortfall of US $275 million, of which US
$60 million is still needed for activities in 2002.
The partners are working very hard to overcome the funding
gap working with public donors, foundations, and the private
sector. Rotary International, which has already contributed
US $462 million to the Initiative, will launch a new membership
fundraising campaign aimed at raising US $80 million.
Q What is being done to reach all children, particularly
those affected by conflict?
Maintaining access to all children continues to be a challenge.
In India's high transmission areas, reaching minority
populations is the greatest challenge. Conflict affects
access to geographic areas of Angola, Somalia and Afghanistan
and poses a particular challenge to the eradication initiative,
putting children beyond the reach of vaccinators. The
success of the UN Secretary-General and other partners
in establishing days of tranquillity, or corridors of
peace, for NIDS in DR Congo, Sri Lanka, Afghanistan, Sierra
Leone and other countries demonstrates that it is possible
to reach children affected by conflict if the resources
and political will are in place.
In an effort to reach all children, including the most
geographically isolated and those affected by conflict,
vaccinators are moving from dwelling to dwelling, settlement
by settlement to protect children against poliomyelitis.
Q As more countries are free of it, what happens to
the wild poliovirus?
As an increasing number of countries become polio-free,
the virus is safely and securely stored in a limited number
of laboratories to ensure no inadvertent release occurs
after eradication. A unanimous resolution at the World
Health Assembly in May 1999 called for all laboratories
to either transfer virus to designated WHO repositories,
implement high containment procedures or destroy stocks
of the virus if they are not useful to research.
Q Why can't countries stop vaccination after certification?
The decision as to when and how any country stops vaccination
must be viewed in a global perspective. Until global certification
of poliomyelitis eradication, all areas remain at risk
of importation of poliovirus and must ensure high population
immunity to maintain polio-free status.
There are a number of benefits and challenges to stopping
polio vaccination. Extensive research is required before
a decision regarding post-certification immunization policy
can be made.
The global TCG has reaffirmed the appropriateness of
the goal of stopping immunization and has intensified
its work on the evolving issue of post-certification immunization
Q Does poliovirus present a significant threat as
a biological agent?
Poliovirus presents a low level risk as a potential
biologic agent relative to agents such as smallpox and
anthrax. Intentional use of poliovirus as a biological
agent would be inefficient, as less than 1% of those infected
become paralysed and less than 0.1% die. The potential
for poliomyelitis to be disseminated to large populations
is low, as poliovirus is sensitive to drying and does
not survive in the environment. High immunization coverage
at this point in time further reduces the potential to
spread the virus. Public health preparedness to detect
and control poliomyelitis is currently high.
Q What is the risk of an outbreak of circulating vaccine-derived
Polio outbreaks due to circulating vaccine-derived polioviruses
(cVDPV) are rare, but possible. An estimated 10 billion
doses of OPV were administered world-wide between 1997
and 2001, a period during which there has been very high
quality surveillance globally, yet only two cVDPV outbreaks
have been confirmed in that period. The outbreaks, in
Hispaniola and the Philippines, appear to have been stopped
by supplemental immunization activities with OPV.
One previous occurrence has been documented in Egypt
between 1988 and 1993. Common to all three outbreaks were
a high number of previously unvaccinated people, which
may have provided the conditions for VDPVs to circulate
and cause disease.
Q What are the implications of cVDPV for the global
These outbreaks demonstrate the need to maintain high
routine immunization coverage in all areas, to ensure
high quality surveillance, and to accelerate the programme
of work to determine the most appropriate immunization
policy for the post-certification era, particularly if,
when and how to stop use of OPV.
Q What is the 'endgame' of poliomyelitis eradication?
"Polio endgame" is the current working title
for the phase of the Global Polio Eradication Initiative
that aims to minimize the risks of a re-emergence or re-introduction
of poliovirus and optimize the benefits of polio eradication
in the post-certification era (i.e., after certification
that transmission of the wild poliovirus has been interrupted).
The polio endgame is a three-part programme of work which
involves the containment of wild poliovirus stocks, certification
of the interruption of wild poliovirus transmission and
the development of post-certification immunization policy
for polio. As we get closer to interrupting transmission
of poliovirus, these endgame issues become increasingly