Immunization, Vaccines and Biologicals


Polio (poliomyelitis) is a highly infectious disease caused by a virus. It invades the nervous system and can cause irreversible paralysis in a matter of hours. Polio is spread through person-to-person contact. When a child is infected with wild poliovirus, the virus enters the body through the mouth and multiplies in the intestine. It is then shed into the environment through the faeces where it can spread rapidly through a community, especially in situations of poor hygiene and sanitation. If a sufficient number of children are fully immunized against polio, the virus is unable to find susceptible children to infect, and dies out.

Most infected people (90%) have no symptoms or very mild symptoms and usually go unrecognized. In others, initial symptoms include fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs.

There is no cure for polio, only treatment to alleviate the symptoms. Heat and physical therapy is used to stimulate the muscles and antispasmodic drugs are given to relax the muscles. While this can improve mobility, it cannot reverse permanent polio paralysis.

Polio can be prevented through immunization. Polio vaccine, given multiple times, almost always protects a child for life. The development of effective vaccines to prevent paralytic polio was one of the major medical breakthroughs of the 20th century. With the development and evaluation of bivalent oral polio vaccine in 2009, the Global Polio Eradication Initiative now has an armory of five different vaccines to stop polio transmission:

  • Oral polio vaccine (OPV)
  • Monovalent oral polio vaccines (mOPV1 and mOPV3)
  • Bivalent oral polio vaccine (bOPV)
  • Inactivated polio vaccine (IPV)

If enough people in a community are immunized, the virus will be deprived of susceptible hosts and will die out. High levels of vaccination coverage must be maintained to stop transmission and prevent outbreaks occurring.

In May 2012, the World Health Assembly declared the completion of polio eradication a programmatic emergency for global public health and requested the Director-General to rapidly finalize a comprehensive eradication and endgame strategy for the period 2013-2018. The draft strategic plan and current status of the global polio eradication program were presented to SAGE. Noting the substantive progress made in implementing polio emergency action plans in the remaining polio infected countries, detailed attention to oral polio vaccine (OPV) campaign planning in the field, and new evidence in improving performance, SAGE was alarmed by the considerable funding shortfalls at a time when eradication is in sight, with OPV campaigns already cancelled or scaled back in over 25 high risk countries in 2012.

In November 2012, SAGE endorsed the four major objectives and milestones in the new strategic plan. SAGE also recommended that all countries should introduce at least one dose of inactivated polio vaccine (IPV) in their routine immunization program to mitigate the risks and consequences associated with the eventual withdrawal of the type 2 component of OPV (OPV2). SAGE will review progress on achieving the pre-requisites for OPV2 withdrawal, including the availability of affordable IPV products, every six months to ensure the earliest possible date for OPV2 withdrawal but with sufficient advance notification to ensure programmatic readiness and vaccine availability.

In the new Eradication and Endgame strategy, research is a vital component of the Global Polio Eradication Initiative, providing the necessary evidence to guide the final steps to a lasting polio-free world and beyond. The Global Polio Eradication Initiative coordinates and supports an extensive program of research from a wide range of core scientific disciplines. The research program has two broad objectives:

  • to identify, develop and evaluate new tools and tailored approaches to maximize the impact of eradication efforts
  • to inform long-term policy for the post-eradication era.

See more at:

WHO position papers

Polio Eradication and Endgame Strategic Plan 2013-2018

Related links

Page last updated: 16 June 2014


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