Polio Eradication Program: Where do we stand in 2024?
When a global polio eradication program was first mooted in 1988, the task seemed immense. At that time wild polio virus (WPV) was being reported in over 125 countries globally with more than 350,000 cases annually. Yet, by 2002, three WHO regions (Americas, Western Pacific, and Europe) were declared free of circulating poliovirus and by 2005 only 4 countries were considered “endemic” for the virus. These countries were India, Nigeria, Pakistan, and Afghanistan.
This was an amazing achievement. The task of mopping up these last few areas seemed within reach. Unfortunately, total eradication became elusive with many outbreaks being reported in previously polio-free countries because of travel from endemic locations.
Transmission of the wild polio virus has since been interrupted in Nigeria and India, but cases are still being reported in Afghanistan and Pakistan.
Prior to 1988 there were 3 circulating strains of wild polio virus (wild polio virus type1 (WPV1), wild polio virus type 2 (WPV2) and wild polio virus type 3 (WPV3). Wild polio virus type 2 was declared eradicated in 2015 and wild polio virus type 3 was last reported in 2010. These successes allowed for the removal of polio type 2 virus from the trivalent Sabin vaccine in 2016.
In a recent situation report (January 2022 to December 2023), a total of 12 cases of WPV1 were reported to WHO during 2023 as against 22 in 2022. Six cases each were reported in Afghanistan and Pakistan in 2023. The number of cases attributed to circulating vaccine-derived paralytic polio (cVDPV) has also decreased in the same period, from 881 cases in 2022 to 524 in 2023. See Progress Toward Poliomyelitis Eradication.
An increase in cVDPV cases may reflect falling rates of immunity in the wider community ie vaccination protection levels. We know the global pandemic had a major impact on global immunization programs, and it will take a few years to catch up to a desired level of over 85% cover.
Polio eradication may be achievable in the next few years, but it will take an even greater effort in those regions where WPV1 is circulating. It will also require a sustained childhood vaccination program in regional areas where conflict and poor public health infrastructure pose major obstacles.
The history of polio can be reviewed at Polio Global Eradication Initiative.
Related: What is vaccine-associated paralytic polio (VAPP) ?
Did you know?
There are ancient Egyptian depictions of people with withered legs and young children walking with canes. These are likely cases of people who have contracted polio.
Rotary International launched PolioPlus in 1985 with an initial pledge of US $120 million. This is seen as one of the largest private-sector initiatives in public health. It was a catalyst for the Global Polio Eradication Initiative (GPEI) in 1988.
It is estimated that more than 2.5 billion children have been vaccinated for polio since 1988 and this has prevented more than 16 million cases of paralytic polio.
