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Amid a polio outbreak, hope arrives in DRC with renewed commitment to vaccine coverage

October 22, 2018 by PATH

Widespread vaccination is the surest way to halt vaccine-derived poliovirus outbreaks, a tenacious threat of the pre-eradication era.

Girl gets polio vaccine_Photo: Richard Franco

National commitments to stronger routine immunization in DRC mean greater protection against polio and other vaccine-preventable diseases for the country’s children. Photo credit: Richard Franco.

Almost a year after the polio outbreak in DRC was declared a public health emergency, a new hope has emerged. In October 2018, the governors of Tanganyika and Haut-Lomami Provinces signed a four-year commitment to improve routine immunization, which is the best way to protect children from illness, control the outbreak, and keep the provinces polio-free.

This new commitment will help both provinces reach and maintain a goal of more than 90 percent immunization coverage by improving cold chain and vaccine logistics, strengthening governance and management of routine immunization programs, enhancing technical capacity, bolstering community engagement, and improving data management and analysis.

PATH will continue to be a close partner to help guide DRC as the country works to contain this outbreak and improve routine immunization, coordinating implementation with a network of other key stakeholders. Along with technical guidance, we will lead advocacy efforts to ensure these new technical and financial commitments translate into provincial policy that reach coverage goals. Reaching the hardest-to-reach is a goal we cannot afford to miss.

Outbreaks flourish where there’s patchy vaccine coverage among the most vulnerable, and the case of DRC puts a spotlight on one of the most tenacious threats of the pre-eradication era: circulating vaccine-derived poliovirus (cVDPV), a rare side effect in which the weakened virus used in the vaccine reverts back to its virulent form in the environment.

“Individuals vaccinated with OPV gain protection from this lurking threat before the virus can spread further and wreak havoc in underimmunized communities.”

DRC saw its last case of wild poliovirus in the year 2000, but this cVDPV outbreak is emblematic of our global paradoxical price of success: while in 2017 there were only 22 cases of wild poliovirus worldwide, there were about 90 cases of cVDPV. Multiple steps forward, a couple steps backward still equal a net positive outcome. As wild polio cases continue to disappear from the globe, the control of cVDPV is also an important target to rid the world of all types of polio.

Since cVDPV is a (rare) consequence of oral polio vaccine (OPV) in under-immunized communities, the global response to support a swift and thorough OPV immunization campaign in DRC may seem like a counterintuitive way to combat it. But only OPV can prevent person-to-person disease transmission and is the best protection against lurking cVDPV in the environment that can pick up virulent strength as time goes by – a phenomenon called genetic drift.

Individuals vaccinated with OPV gain protection from this lurking threat before the virus can spread further and wreak havoc in underimmunized communities. Regardless of whether a poliovirus outbreak is wild or vaccine-derived, time is of the essence, and swift delivery of OPV is our best line of defense. These new provincial commitments will further fortify the country’s children against any future threats of cVDPV. Vaccines will be needed for several years to come.

In addition to helping country governments meet commitments, PATH works alongside global vaccine manufacturers to help increase polio vaccine supply and affordability for high-risk countries. And we are at the same time also looking for ways to improve current tools. We manage a consortium of partners to conduct early-stage clinical trials on novel oral polio vaccine (nOPV) candidates that we hope will have the same efficacy as currently available OPV with less risk of seeding future outbreaks . If successful, nOPV could be deployed during an outbreak to halt disease transmission without allowing polio to maintain a lingering foothold.

Our aim, after all, is polio eradication. And that leaves no room for lingering footholds.

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