With polio eradication in sight, WHA fears setbacks

Polio is on the brink of becoming only the second human communicable disease to be eradicated, after smallpox. So why were representatives at this week’s World Health Assembly so nervous? “We have a lot to do in order to reach the complete eradication goal set for the end of 2026,” the delegate from Monaco said during a session Wednesday. “COVID-19 demonstrated the fragility of the progress made.” It also interrupted routine vaccination efforts, increasing the number of children who are at risk of contracting the virus. That’s why, 35 years after the Global Polio Eradication Initiative was launched at WHA, delegates celebrated significant gains — Aiden O’Leary, director of polio eradication at the World Health Organization, told the WHA that 20 million people who can walk might not have been able to if they have contracted the virus — while warning that those steps forward are extremely fragile. And they pressed for greater financial commitments to improve vaccination and surveillance efforts to reach full eradication. Wild poliovirus type 1 is now endemic in the smallest geographic area ever recorded — only parts of Afghanistan and Pakistan, according to O’Leary. Nevertheless, it remains the only ongoing public health emergency of international concern. A polio eradication report from the WHO director-general laid out two goals the office identified as key to ending transmission and eradicating polio by 2026. The first is to interrupt all remaining poliovirus transmission chains. The numbers are dwindling. Pakistan was down to only a single active transmission chain at the start of this year. And in Afghanistan, the wild poliovirus is primarily circulating in two of the country’s 34 provinces, according to O’Leary. But that could change quickly. COVID-19 led to an increase in the reservoirs of children who have received no routine vaccinations, known as zero-dose children. If polio reaches those communities, it could spread rapidly and quickly reestablish itself. The second goal is to stop the circulation of polio that is derived from the vaccine. It is a rare occurrence, but can happen when a vaccine using a weakened but live virus is administered in an area with low immunization rates. The live virus can be excreted and then circulate in those communities. Since 2020, vaccine-derived poliovirus of all three types has circulated in 51 countries and one territory, including seven countries that have reported more than one type of the virus in circulation. The WHO report called for increased surveillance and immunization, but specifically in the regions that account for most of those cases. That left some country delegates warning the agency not to lose sight of the rest of the world. “I urge the secretariat not to lose focus on countries that are in a state of vulnerability, though listed as non-endemic,” the representative from the Bahamas told the WHA. At the same time as countries are preparing to eliminate transmission, they are also implementing plans to make sure the disease doesn’t return. WHO had identified 20 polio-priority transition countries where most existing polio eradication resources are already concentrated or which were identified as particularly fragile. The goal of the transition is to put in place systems that will help them sustain a polio-free status once they achieve it, while also strengthening immunization systems and emergency preparedness more broadly. Ahead of O’Leary’s warning that “as long as there is transmission anywhere, then potentially everywhere is at risk,” countries spent much of Wednesday outlining progress they had made toward implementing the WHO’s transition plan. That included switching to vaccines that carried less risk of creating vaccine-derived cases of polio, beefing up surveillance systems, and integrating polio immunization into their public health system. They also responded to the secretariat’s efforts to help with these initiatives, including policy guidance and technical support, which were outlined in a new report from WHO. While they welcomed the interventions, many governments — both those where polio still appears and those at risk — asked for more financial resources to protect themselves. Countries like Indonesia and the Philippines were also looking for cheaper vaccines. In comments at the WHA Wednesday, Medicus Mundi, an international network committed to universal health care access, suggested promoting local production of polio vaccines, to ensure an uninterrupted, affordable supply of vaccines. The United States delegation also pushed for improved efforts to secure poliovirus used in a laboratory setting, warning of the dangers if the facilities were caught up in a conflict without a strategy for preventing the virus’ escape. Ultimately, the delegates were determined to seal off any risk of losing the gains made over the past 35 years. “History is about to witness the human miracle of the eradication of a second disease,” the delegate from Qatar said. But only by “stay[ing] the course and dig[ging] deep to do what needs to be done.”