What’s the Polio Endgame?
Illustration by Science Picture Co/Science Source
Eradication "endgame" generally refers to the strategy from the point when cases are few and interruption of transmission seems likely, and extends through confirmation of eradication. Since the polio program began 27 years ago, there have been at least four “all-out” endgame-type campaigns. They commence with the announcement that eradication was just over the horizon and special pleas for support and funds. Vaccination strategies and surveillance methodologies were massaged, but basically the approaches were similar. The current campaign was expected to record its last polio case in 2014 with confirmation of eradication in 2018. However, that effort has failed. Yet another set of target dates awaits revised budgetary decisions.
Will the present endgame have a different character? Will a new Chevrolet be substantially different from last year’s model?
D.A. Henderson, MD, MPH ’60, led WHO’s successful global smallpox eradication campaign and is a Dean Emeritus of the Bloomberg School.
Polio transmission was not ended in 2014—another deadline missed. The good news is that a polio-free Africa is a real possibility if Nigeria’s current good performance continues. But keeping polio out is a tall order with elections looming and insecurity in the North. Pakistan, with a deeply troubled and dysfunctional program, is another story. It is likely to be the virus’s last refuge. Surrounding countries will need to maintain strong programs to keep Pakistan’s poliovirus out.
With sustained transmission continuing deep into 2015, we are not yet at the endgame. The challenges are the costs and logistics of introducing inactivated polio vaccine (IPV) globally and delivering vaccination through routine immunization rather than campaigns (the bedrock of the eradication program). This leaves the burning question: Will eradication of a single disease through a vertical program ever be attempted again?
Sir Liam Donaldson, MD, MSc, is chair of the Independent Monitoring Board of the Global Polio Eradication Initiative.
What do you call a doctor, a writer and several schoolgirls? A polio eradication team. That’s what I found in 2006, as part of a WHO field operation at the Pakistan-Afghanistan border. The task was incredibly daunting since success came down to one number: zero.
My hope, as separate from my opinion, on the polio endgame remains about the same now as then. The former burns bright for outright eradication. The latter suggests that a long-term plan for control is the most sensible and achievable solution for the next 10 years.
Omar Khan, MD, MHS ’97, is associate vice-chair of the Department of Family and Community Medicine for the Christiana Care Health System.
Eradication of smallpox is the only example of successful elimination of a human pathogen, which led to cessation of all immunizations. Eradication of poliomyelitis and its endgame will be different because high population immunity must be maintained to prevent polioviruses from restarting circulation. Therefore it will be a transition from the efforts to stop transmission of wild and vaccine-derived polioviruses to a long-term/indefinite period of universal global immunization and active surveillance. It will involve introduction of a new generation of vaccines for sustainable routine vaccination and development of a global monitoring program.
Konstantin Chumakov, PhD, is an associate director of the FDA Office of Vaccines Research and Review.
The poliovirus eradication endgame is complicated by the ability of vaccine strains of live poliovirus used for oral immunization to mutate, reacquire virulence, circulate and cause disease where vaccination levels are low. A solution is to switch to use of the inactivated vaccine, but this vaccine may not provide sufficient intestinal immunity to prevent virus infection and spread, and requires shots and therefore is more difficult to deliver safely. A period of combined use of the inactivated vaccine (prevents disease) followed by the live oral vaccine (prevents infection) may be necessary. Eventual discontinuation of the live vaccine will be required to prevent continued appearance of vaccine-derived polio.
Diane Griffin, MD, PhD, is the former chair of W. Harry Feinstone Department of Molecular Microbiology and Immunology.