New momentum towards polio eradication

The last big hurdles

Led by the World Health Organization (WHO), the GPEI first brought all global public health stakeholders together in 1988 behind the ambitious eradication goal. At that time, polio was endemic in 125 countries with more than 350,000 children paralyzed each year. Now, only two countries still see endemic wild poliovirus transmission. That’s resulted in a 99.9% decrease in paralytic cases caused by infection with wild poliovirus, with 18 million people who would otherwise have been paralyzed, able to walk today.¹

And yet, until polio is fully eradicated, there will always be risks of resurgence in populations that are under-protected due to lack of consistent routine access to all necessary vaccines.  “As an example, recently, many routine pediatric vaccination programs were halted or disrupted due to the COVID-19 pandemic. Catching up will be key to preventing a rise in cases in many countries worldwide.” said Emmanuel Vidor, Global Medical Lead for Polio at Sanofi Pasteur.

In 2020, nearly 70% of countries surveyed by the WHO reported that routine immunization programs (including polio) saw disruption due to the pandemic.² A year later, almost 40% of countries still reported ongoing disruption of their vaccination programs.³ This includes some developing countries where vaccination levels for polio and other childhood diseases were still at precarious levels before the pandemic.⁴

Another challenge to eradication is related to complications arising from the use of oral live attenuated (weakened) polio vaccines (OPVs).  OPVs are used in many developing countries to help prevent transmission of poliovirus through the immunity they induce in the digestive tract. Unfortunately though, OPV can, in one in a million vaccinations, cause paralytic polio in the vaccinated person.⁵ And on very rare occasions in under-immunized populations, the live attenuated virus used in OPV can mutate and circulate in a community. This is known as circulating vaccine-derived poliovirus (cVDPV).⁶ cVDPVs that develop from the ongoing, necessary use of currently available OPVs add a complicating factor to ending polio transmission for good, due to the potential of cVDPVs to cause future outbreaks. That’s why it’s critical to achieve full immunization of entire populations, to ensure they are protected against both vaccine-derived and wild polioviruses.⁶

Doubling down on IPV doses

Taken together, these public health challenges have led to a rise in the number of paralytic polio cases in dozens of countries around the world.⁷

“That’s why, as a partner in the GPEI efforts, we continue to supply a maximum amount of injectable inactivated polio vaccine doses (IPV) either as standalone vaccines or included in pediatric combination vaccines that help prevent up to six diseases in the same vaccine series, in order to help raise immunity across communities and to help eliminate polio,” explained Emmanuel.

These doses are more important than ever as the WHO has recommended that countries not using pediatric combination vaccines implement a two-dose IPV regimen on top of any OPV doses already delivered through their immunization programs. While some low- and middle-income countries have already implemented a one-dose schedule, the second dose, if implemented broadly, will help improve protection against polio and pave the way for a transition toward an IPV-only routine vaccination schedule over the long- term.

The endgame: a pivotal time

For 40 years, Sanofi has supplied billions of polio vaccine doses worldwide. Today, the end is in sight, so this last push is crucial.

“This is a pivotal time in the longstanding global polio eradication effort,” concluded Emmanuel. “We are nearly there, and yet the last hurdle will be our highest. I know that the willpower, the commitment and the energy of all GPEI partners and supporters is there, as are the valiant efforts of frontline health workers, all of whom will never give up until this major human achievement is complete.”