Since the eradication of smallpox in the late 1970s, no other diseases have followed suit; the goal that has come closest so far is eradication of polio. The development of vaccines in the 1950s led to cases of polio plummeting: whereas hundreds of thousands were affected annually in the middle of last century, in 2012 around 250 people were paralysed by the disease. But the final stages of eradication are proving more difficult than the early phases. The disease remains entrenched in three countries—Afghanistan, Nigeria, and Pakistan—where social, political, and logistical factors prevent effective vaccination campaigns and lead to export of virus to countries that have previously been free of the disease.
As Haris Riaz and Anis Rehman reported in the journal last month, the global polio eradication programme suffered a grave setback in December last year when seven vaccination workers were shot dead by terrorists as they took part in a 3 day campaign to deliver vaccine in Karachi and Peshawar. At the end of January, two more vaccine workers were killed in a landmine explosion in the Kurrum tribal region. These two latest casualties are not thought to have been directly targeted, but unwitting victims of sectarian violence.
Such events are not only tragic losses—people dedicating their time to a global health effort senselessly killed—but also they leave children who would have received vaccine unprotected and allow the virus to continue to circulate. The consequences of which can be extremely far reaching: in January, poliovirus related to strains circulating in Pakistan was detected in sewage samples in Cairo, Egypt, more than 3000 km away (the last case of polio in Egypt was recorded in 2004). No new cases of polio have been recorded in Cairo, but health authorities are surveying the impoverished districts of Al Salam and Al Haggana where the virus was found for recent cases of paralysis, and vaccination campaigns have been initiated.
In the middle of the 20th century, children in developed countries of Europe and North America would return to school at the end of the summer break and look around to see empty chairs of classmates who had not returned because they had been crippled or killed by polio. When the global polio eradication initiative (GPEI) was launched in 1988, the disease was endemic in 125 countries and caused paralysis in around 350 000 people every year. Recent events highlight how a threat that for many is thankfully a distant memory—or for younger generations in some developed countries unknown—remains a real and present danger.
The Bill & Melinda Gates Foundation is one of the major contributors of financial aid to the polio eradication effort, and speaking recently in London at the Richard Dimbleby lecture, Bill Gates reiterated his commitment to wiping out the diseases, highlighting the new eradication target of 2018. On January 23, the GPEI published a draft Polio Eradication and Endgame Strategic Plan (2013—18). The plan has four main objectives and four milestones for eradication. The four objectives are, detection and interruption of wild poliovirus, strengthening of routine immunisation and withdrawal of the oral polio vaccine, containment and certification (enabling some facilities to store poliovirus and outlining the processes for certification of eradication), and legacy planning to ensure that resources put aside for polio eradication are repurposed when the goal is achieved. The milestones for the new strategic plan are for the last case of wild polio by 2014, withdrawal of type 2 oral polio vaccine by 2015—16, worldwide certification of polio eradication by the end of 2018, and cessation of bivalent oral polio vaccination during 2019.
This is not the first deadline for polio eradication. When the GPEI was set up, the planned date for eradication was 2000. As the cases become fewer, the problems become knottier, and hindrances to final eradication become ever more dependent on localised factors and characteristics of the virus’s remaining toeholds. As the saying goes, the devil is in the detail.
The new plan encouragingly contains intricate analyses of recent outbreaks in the three remaining countries, reasons for programmatic declines, and reflection on the lessons learned from success in India, which has not recorded a case in more than 2 years. It is an excellent example of how data, local knowledge, and experience can be synthesised to provide clear goals and realistic targets. 2018 seems soon, but for some children it will not be soon enough. And for the vaccination workers who have lost their lives, eradication of polio within 5 years would be a tribute to their efforts.