Africa declared free of wild polio, but vaccine-derived polio threat remains

Africa has been declared free of the wild Poliovirus, after decades of effort.

In summary:

  • No cases of wild poliovirus have been reported in Africa for four years
  • This is just the second time a virus has been eradicated in Africa
  • Cases remain of a vaccine-derived strain of the disease

The announcement, by the African Regional Certification Commission for Polio Eradication, comes after no cases were reported for four years.

But cases of vaccine-derived polio are still sparking outbreaks of the disease in more than a dozen countries.

Polio once paralysed some 75,000 children a year across the African continent.

Pakistan and neighbouring Afghanistan are now the only countries thought to still have the wild poliovirus.

In both countries, vaccination efforts against the highly infectious, water-borne disease are complicated by insecurity and attacks on health workers.

African health authorities see the declaration as a rare glint of good news in Africa amid the coronavirus pandemic, an Ebola outbreak in western Congo and the persistent deadly challenges of malaria, HIV and tuberculosis.

The World Health Organization (WHO) says this is just the second time a virus has been eradicated in Africa, after the elimination of smallpox four decades ago.

“This is an incredible and emotional day,” WHO Africa director Matshidiso Moeti said.

But she urged vigilance, saying coronavirus threatened vaccination and surveillance efforts.

Vaccine-derived polio virus remains

This new declaration doesn’t mean Africa is polio-free.

The continent still sees cases of vaccine-derived polio, which is a rare mutated form of the weakened but live virus contained in the oral polio vaccine.

This weakened form of the virus can pass among under-immunized populations and eventually changes to a form that can cause paralysis.

That mutated virus can spark crippling polio outbreaks, and 16 African countries are currently experiencing cases: Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Ivory Coast, Congo, Ethiopia, Guinea, Ghana, Mali, Niger, Nigeria, Togo and Zambia.

“We must stay vigilant and keep up vaccination rates to avert a resurgence of the wild poliovirus and address the continued threat of the vaccine-derived polio,” Ms Moeti said.

COVID-19 disrupts vaccination programs

Patchy surveillance across the vast continent of 1.3 billion people also raises the possibility that scattered cases of the wild poliovirus still remain, undetected.

Health authorities have warned that the coronavirus pandemic has disrupted vaccination work in many countries across Africa, leaving more children vulnerable to infectio

In April, WHO and its partners reluctantly recommended a temporary halt to mass polio immunization campaigns, while recognizing the move could lead to a resurgence of the disease.

In May, they reported that campaigns to vaccinate children against polio had been suspended in 38 countries, mostly in Africa, as a result of the coronavirus pandemic.

Eradicating polio requires more than 90 per cent of children being immunized, typically in mass campaigns involving millions of health workers that would break social distancing guidelines needed to stop the spread of COVID-19.

Health officials had initially aimed to wipe out polio by 2000, a deadline repeatedly pushed back and missed.