A Polio-Free World Will Trigger New Challenges



Trained healthcare workers, Latif, Shahida and Abib, crisscross Pakistan by bus and on foot. Small cool boxes packed with the polio vaccine for children slung over their shoulders, they go tirelessly door to door to make sure every child in every village is vaccinated. Doors are now opened and the staff welcomed, but it wasn’t always the case. At one time families were suspicious of the vaccine and would hide their children. When the vaccination campaign started in Pakistan in 1995, there were thousands of cases of polio. Today, there are just three, but as Mohammed, who works as a vaccinator in Pakistan, emphasizes: "We must not lower our guard because new cases could resurface."

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Polio in Afghanistan 

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Polio in Pakistan

 

In 1988, when the Global Polio Eradication Initiative (GPEI) was established, 10 children around the world were permanently paralyzed by polio every 15 minutes1. The GPEI launched routine immunization programs, catch-up campaigns and robust surveillance, leading to a gradual wave of countries been certified as "polio-free". The Americas region was the first in 1994, followed by the Western Pacific region in 2000 and Europe in 2002. In 2011, the last polio case was declared on the Indian subcontinent and the African continent was certified "polio free" in 2016. However, there have been cases of resurgence in Nigeria and, more recently, in the Democratic Republic of Congo people have been infected by the virus derived from the oral vaccine. 

Oral polio vaccine (OPV) contains a weakened vaccine-virus that replicates in the intestine for a limited period. During this time, the vaccine-virus is also excreted. On rare occasions, if a population is seriously under-immunized, an excreted vaccine-virus can continue to circulate for an extended period of time. In rare instances, the vaccine-virus can genetically change into a form that can paralyze – this is known as a circulating vaccine-derived poliovirus2

It is estimated that the polio vaccine gave more than 16 million people the chance to walk; without it they would be facing a life with paralysis1.

The final push towards eradication

In 2018, polio is endemic in three countries and has yet to be controlled: Afghanistan, Nigeria and Pakistan. Endemic polio transmission, which continues in these countries, could result in nearly 200,000 new cases annually worldwide over the next 10 years3. It is therefore imperative not to give up or rein in our efforts.

Unlike smallpox, the only transmissible human disease eradicated to date, polio can remain asymptomatic, which facilitates the silent circulation and transmission of so-called “wild” virus strains. Vaccine-derived polioviruses, particularly from the oral vaccine that is easier to administer, can also cause resurgence of the disease.

To alleviate these situations, a new control plan was presented by World Health Organization (WHO) in 2013 to simultaneously eliminate all types of poliomyelitis, both the wild poliovirus and poliovirus derived from the vaccine. This plan, developed with countries impacted by polio, stakeholders, donors, provides for the combination of two types of vaccine: the injectable IPV (Inactivated Polio Vaccine), and the oral OPV bivalent (Oral Polio Vaccine for strains 1 and 3) that replaces4 the trivalent oral vaccine for strains 1, 2 and 3.
 
"The OPV alone has done fantastic work as part of the Global Polio Eradication Program, but its intrinsic limitations and shortcomings in its use in the field5 make reaching a polio-free world difficult without a drastic improvement in the economic situation of many countries,” says Emmanuel Vidor, AVP Global Medical Affairs at Sanofi Pasteur. “In this context, only a global deployment of IPV, also facing industrial and operational constraints, can guarantee a world without poliovirus paralysis. At the same time, there is an unavoidable role for the current version of OPV, or an improved version, to definitively eliminate the circulation of the polioviruses."

The implementation of this new immunization schedule is coordinated on a global scale and is carried out with the active collaboration at an international and local level of all the actors involved in the eradication: national governments, the WHO, Rotary International, the United States Centers for Disease Control and Prevention (CDC), UNICEF, Gavi the Vaccine Alliance and the Bill and Melinda Gates Foundation. Sanofi Pasteur is one of the world's leading suppliers of both oral and injectable vaccines, providing the bulk of the needs for the latter.

Preparing for life without polio

We are close to a world without polio, but when the last case of paralysis linked to the wild virus has been identified and polio eradication is formalized6, will we really be done with this crippling disease? Nothing is less sure. We still need to anticipate the problems that could negate the efforts that have been made over the past decades. We must start thinking about tomorrow today.

One of the main challenges will be to continue to mobilize all stakeholders, who have been part of the eradication program for years, as well as respond to potential skepticism about the need for continued immunization when the disease is no longer officially present.

"It will be necessary to organize an ecosystem with governance at the global level that will take over from the GPEI - whose mission will end when eradication is certified - and funding for the poorest countries,” says Corinne Bardone, Public Affairs Officer for polio vaccines at Sanofi Pasteur. “This most likely will be via Gavi the Vaccine  Alliance, so that it can continue to vaccinate the global pediatric population and maintain both high vaccine coverage rates with inactivated polio vaccine to prevent resurgence and surveillance of circulating viruses. This imperative is self-evident today, but what will happen when the disease has been declared extinct? That's why we need to prepare for the post-eradication phase now to ensure an adequate and sustainable supply of inactivated polio vaccine even after eradication is achieved." 

The main supplier of both vaccines, OPV and IPV, Sanofi Pasteur has been a leading partner of the GPEI since its launch” declares David Loew, Executive Vice President, Sanofi Pasteur. “We have provided more than six billion doses of OPV and significant quantities of IPV vaccines at affordable prices. The company’s biotechnological know-how has made it possible to produce these commercially available vaccines so that every child, anywhere in the world, can benefit.”

Sanofi Pasteur is mobilized so that the questions asked about post-eradication are being discussed now. On October 22, its teams organized a debate at Sanofi’s headquarters in Paris. A panel of experts, Michel Zafran and Roland Sutter of the WHO - respectively Director of the Polio Eradication Program and Research Coordinator - Rotary representatives and field workers in Pakistan, Afghanistan and Africa discussed barriers to eradication and post-eradication challenges.

Follow the debate “The Global Effort To Eradicate Polio: Is It Time To Stop?”

 

References

  1. http://www.who.int/en/news-room/feature-stories/detail/unsung-heroes-on-world-polio-day 
  2. http://www.who.int/features/qa/64/en/
  3. http://www.who.int/news-room/fact-sheets/detail/poliomyelitis 
  4. To eliminate all risks associated with type 2 and to gain efficiency
  5. OPV has a limited efficacy (15 to 20 doses are sometimes necessary to provide protection) and it can potentially recreate virulent circulating- Vaccine-Derived-Polio-Viruses under certain conditions
  6. After a period of three years without a new case of paralysis related to wild polio virus