The Final Push for Polio

Monday, 10th of September 2012

THE FINAL PUSH FOR POLIO

The Lancet Infectious Diseases, Volume 12, Issue 8, Pages 591 - 592, August 2012

At first glance, efforts to eradicate poliomyelitis seem in excellent shape. “Epidemiologically, the picture has never looked better”, WHO's Oliver Rosenbauer told TLID. Only 88 cases have been reported in 2012, a favourable contrast with the 252 cases reported by same time last year. India has been free of poliomyelitis since January, 2011, which resolves any lingering questions about the technical feasibility of eradication. Of the three countries classified by WHO as having re-established transmission, Angola has not had a case since mid-2011; the Democratic Republic of the Congo has not had a case since December, 2011; and Chad has only had four cases thus far in 2012—the same period in 2011 had 82 cases.

Elsewhere, outside of the remaining three endemic countries—Afghanistan, Pakistan, and Nigeria—no cases of poliomyelitis have been reported. Moreover, Pakistan has registered a mere 22 cases this year; by this time in 2011, it had registered 58. Wild poliovirus type 2 was eradicated in 1999, and the introduction of monovalent vaccines in 2005, and bivalent vaccines in 2009, provided additional impetus to the global fight for eradication (the new vaccines are roughly three-times as effective as the trivalent vaccine). The strategic plan of the Global Polio Eradication Initiative for 2010—12 aims to cease transmission of the poliovirus by the end of this year. “It would be premature to entirely rule out achieving the end-2012 milestone”, noted the authors of Every Missed Child, a report released by the initiative's independent monitoring board.

Yet, when the World Health Assembly met in May, 2012, it adopted a resolution declaring “the completion of poliovirus eradication a programmatic emergency for global public health”. Meanwhile, experts—including the authors of the independent monitoring board report—routinely use the term crisis when describing the present state of eradication efforts. Why?

There are two key reasons. First, the massive funding gap. The polio campaign for 2012—13 needs a budget of US$2·2 billion, but current funding falls short by $945 million. Thus, 68 campaigns in 33 countries have had to be cancelled. If the money is not provided, 94 million children, mostly in west and central Africa, will not be immunised. In view of the virus's persistence in Nigeria, notes Every Missed Child, “the risk of an explosive return of polio in Nigeria and west Africa is ever-present and raises the chilling spectre of many deaths and a huge financial outlay to regain control”. The global financial benefit of polio eradication has been estimated at $40—50 billion.

The second issue is the absence of meaningful progress, particularly in endemic countries but also in African nations with re-established transmission. Cumulatively, these countries have an estimated 2·7 million children younger than 5 years who have not received even one dose of vaccine. Even more children have been insufficiently vaccinated. If not addressed, the consequences could be severe. “We're seeing all over the world a build up of young adults who were never exposed to poliovirus, because polio has been eradicated from their area and there have been declining vaccination coverage levels”, explains Rosenbauer. “If poliovirus gets in this group, there could be some really devastating outbreaks, far deadlier than we have seen in the past.” Mathematical modelling suggests the possibility of incidences of 200 000 cases per year within the next decade, wiping out nearly all the gains of the 24 years since the international community committed to eradication of polio.

In west Africa, for example, insecurity in Mali, the food crisis in the Sahel, and the onset of the rainy season means that population movement is greater than normal. Nigeria has already seen 52 cases this year; two-thirds of the global burden and a sharp increase compared with the same period in 2011. Couple this rise with the scaled-back vaccination campaigns in neighbouring countries and children in the region are particularly vulnerable. An immunisation campaign in the highest risk areas of Burkina Faso, Mali, and Niger was done earlier this month, but a more comprehensive endeavour would be preferable.

Fortunately, problems within the endemic countries should be resolvable. Crucially, polio is not evenly distributed across the three nations. In Afghanistan, it is concentrated in ten high-risk districts in the troubled southern provinces of Helmand and Kandahar. In Pakistan, the disease is concentrated in Gaddap in Karachi, Pishin district in Quetta, and the Federally Administered Tribal Areas bordering Afghanistan. In Nigeria, polio persists in four northern states.

All three countries have issued national emergency action plans, which aim to involve civil society as well as the public sector, much as India did. “The leadership at the top is engaged, in Pakistan in particular we've seen tremendous support from the government at the highest level”, notes Carol Pandak (Rotary International) however, the difficulty is in translating that support to the lower levels. Resistance to immunisation campaigns can be ameliorated by engagment with religious and community leaders—as UNICEF has done in Nigeria, and Rotary International did in India and is attempting in Pakistan. Even the decision by the Taleban to ban vaccinators from some parts of Pakistan need not be insurmountable. “We've been faced with these challenges before”, Pandak points out, “and with the right negotiation they can be overcome.”

Security issues—in Afghanistan, Pakistan, and Nigeria's Borno state—complicate matters. “In Afghanistan, the programme sometimes has to try to access kids during periods of deep instability”, explains Nicholas Grassly (Imperial College London, UK). “Those periods of access are quite variable and some years there will only be a limited amount of times that those kids are accessible.”

Nonetheless, Rosenbauer points out that accessibility is actually increasing in Afghanistan: by March, 2012, only 5% of children were inaccessible, compared with 30% at the beginning of 2011. Yet vaccine coverage in both Afghanistan and Pakistan has decreased over the past few years. “That tells us that the problems are probably more to do with management of the campaigns, operational issues and so forth.” It is a common theme. In Pakistan, for example, polio is concentrated within Pashto-speaking communities. Progress can be made by ensuring vaccinators are the same ethnic origin, speak the same language, and include women on their teams. The independent monitoring board's report praised Pakistan—which it had previously criticised for having a “deeply dysfunctional programme”—for its “revitalised energy and augmented national emergency plan fit for the purpose of stopping polio transmission”.

Experts agree that countries striving to eradicate polio should look to India for inspiration. The Indian Government offered strong support; migrant groups were identified and targeted with immunisation campaigns; large numbers of technical staff were trained and deployed (Nigeria has enacted a huge surge of technical staff—WHO alone has increased the number of its staff in the country from 744 to 2950—and the country has also started using global positioning system technology to help map communities); and an advanced surveillance system was established. “Afghanistan, Nigeria, and Pakistan have all put in place plans that can turn the situation around”, Rosenbauer says firmly. “But we're at crisis point until those plans are fully implemented, and we need funding, otherwise we will see the international spread of polio.”