Monday, 9 May 2016

SAGE advice on polio eradication from SPHPM’s infectious diseases expert Dr Robert Hall

SPHPM Senior Lecturer Dr Robert Hall attended the Strategic Advisory Group of Experts (SAGE) on Immunization for the World Health Organization (WHO) in Geneva on 12-14 April. This was in his capacity as Chair of the Technical Advisory Group (TAG) on Immunization and Vaccine-Preventable Diseases for the Western Pacific Region of the WHO.

Dr Robert Hall has worked in public health for over 30 years and is currently leading the TAG whose role it is to recommend policy to the WHO regional delegates, which is then voted on by the Regional Committee.

Dr Hall reported that the most interesting discussions at the recent SAGE meeting in Geneva were around progress with polio and how to introduce dengue vaccine.

“Polio is going very well. So far this year (to April 19) there have been 11 reported cases of wild polio throughout the world, all of Type 1. There have been no cases of Type 2 or Type 3 for several years now and there have been only three cases of circulating vaccine-derived poliovirus (cVDPV) reported this year,” Dr Hall said.

The cVDPV virus is a direct descendant of the oral poliovaccine virus, it is transmissible and can cause paralysis, and is triggered by low coverage with the oral poliovaccine.

The Western Pacific region comprises 37 countries and stretches over a vast area from Mongolia to New Zealand and from western China to the Pacific Islands, home to 1.8 billion people.

Eradicating vaccine preventable diseases have been the TAG’s major initiatives, and is no small task considering the diverse region encompasses some of the world's least developed countries as well as the most rapidly emerging economies.

The Western Pacific region is home to the biggest country in the world, China, and also the smallest, Pitcairn Island.

However Dr Hall is optimistic that the eradication of polio is within their reach, and countries that haven’t yet done so will begin withdrawing trivalent oral polio vaccine (covering Types 1, 2 & 3) and replacing it with bivalent oral polio vaccine (covering Types 1 & 3), with at least one dose of trivalent inactivated polio vaccine (IPV, covering all types).

“You can imagine how difficult it is to coordinate 194 countries, some with very little administrative apparatus, some at war, and all with competing priorities. However, I think we are winning, and I think that in three to four years’ time we will have seen the end of polio,” he said.

Short-term complications have arisen which may affect the roll-out of the new polio vaccine scheme, and there have been difficulties with manufacturing the quantity of IPV required (hundreds of millions of doses), and there is a 40 per cent shortfall in global supply.

“This shortfall is projected to last for the next 18 months. So there will be delays, and this leads to a risk of cVDPV Type 2 occupying at least some of the niche previously filled by wild polio,” Dr Hall said.

“Disease eradication is a very high-risk, very high-stakes game. It has been described as ‘extreme public health’. If we are successful, it will be one of the most significant achievements of human history. We started this in 1988, so it's been a long, hard slog, but the payoff is for all future generations.”

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