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End Polio Now Position - 25th July 2017

Highlights and global details:

No WPV or CVDPV cases reported this week but six WPV1 positive environmental samples were collected in Pakistan. Health officials from Pakistan and Afghanistan have agreed joint efforts in the border regions and to form separate teams to be sent to the two sides. For polio-free certification purposes the start date is from the onset of paralysis.

 

  WPV cVDPV
2017 to 25 July 8 31
2016 to similar date 19 3
2016 full year 37 7


The most recent WPV1 cases with onset of paralysis were:
•    In Afghanistan – 19 June 2017 so 5 weeks since the onset of polio.
•    In Pakistan - 11 June 2017 or 6 weeks since the onset of polio.
•    In Nigeria - 21 August 2016 or 48 weeks since the onset of polio.

1.    WPV1 cases:

  • 3 cases in Pakistan vs. 13 cases at the same time in 2016. Five country-wide vaccination campaigns have been held in Pakistan since October 2016, preparing for the 2017 c which runs from June until September. The imminent 4-day campaign in Balochistan has constituted nearly four thousand teams to administer the vaccination to the children at their doorsteps.
  • 5 cases in Afghanistan vs. 6 cases at the same time in 2016.
  • No cases in Nigeria. There were no cases in 2015 but cases were identified in 2016 as a result of new initiatives in the northern States where Boko Haram had made access difficult. No new cases since August 2016.
  • No other cases though there is much immunisation activity now in the Lake Chad countries following the Nigerian cases in August 2016. From 25 to 28 March, synchronised polio campaigns took place across 13 countries in west and central Africa including Nigeria, Chad, Cameroon, Guinea, Mali and Niger. Over 190,000 vaccinators immunised more than 116 million children over the campaigns.

The total number of WPV1 positive environmental samples collected in 2017 is 67.

The six samples reported this week were all collected in July. (The environmental presence of viral particles last for 7-14 days.)


2.    WPV2 cases:

•    Declared eradicated September 2015. (Last case was in October 1999.)


3.    WPV3 cases:

•    No cases reported since 10 November 2012. (That was in Nigeria.)

 

There were no cases of cVDPV this week. The cases of cVDPV this year together with the most recent the dates of onset of paralysis were:

  • cVDPV2 27 cases in Syria – 6 June 2017.
  • cVDPV2 4 cases in DRC - 18 April 2017.


1.    cVDPV1 cases:

  • No cases in 2017. Three cases reported in Laos in 2016. In 2015 there were ten cases in Madagascar, eight cases in the Lao Republic and two cases in the Ukraine.


2.    cVDPV2 cases:

  • Four cases in total in DRC and 27 cases in Syria. All the Syrian cases had onset of paralysis between 3 March and 6 June.



Polio is a crippling and potentially fatal infectious disease. There is no cure, but there are safe and effective vaccines. The strategy to eradicate polio is therefore based on preventing infection by immunising every child until transmission stops and the world is polio-free. The source of polio virus transmission is infectious humans but only 1 in 200 infections leads to irreversible paralysis. Of those paralysed, 5% to 10% die when their breathing muscles become immobilised.


Other comments (from the internet and other sources):

I have been asked questions about the cVDPV2 outbreak in Syria from several who receive this report.  The GPEI Reactive Statement and Talking Points on the cVDPV cases I included with a polio position distributed in June but some of the recently added recipients of this report may not have seen it. Some particular items in the Statement were:

  • On very rare occasions, in under-immunised populations, the live weakened virus originally contained in the oral polio vaccine (OPV) can mutate and circulate in the environment, in what is known as circulating vaccine-derived poliovirus (cVDPV). The risk is not so much with the vaccine itself, as with low vaccination coverage. If a population is fully immunised, they will be protected against both vaccine-derived and wild polioviruses. 
  • The ongoing conflict in Syria has devastated health infrastructure and severely disrupted routine immunisation. Although access has been compromised due to insecurity, the Governorate has held several vaccination campaigns against polio and other vaccine-preventable diseases since the beginning of 2016. Two campaigns were conducted in March and April 2017 using the bOPV. However, only limited coverage was possible through these campaigns. 
  • The confirmation of cVDPV in Syria demonstrates that disease surveillance systems are working but it underscores the risk of ongoing vaccination gaps which can give rise to such strains. On all sides of the conflict, there is a common goal to vaccinate all children.

More recently I was asked for comment. I have slightly amended that comment and the update is as shown below. This may be useful to you if you have concerns or questions. We wait to see though what the outcome will be to the WHO response.

  • The polio cases in Syria are from a cVDPV2.
  • There are three types of wild polio viruses and tri valent oral polio vaccine (tOPV) immunises against all three types.
  • All the WPV type vaccines can potentially mutate but it has been WPV2 that has been the biggest problem.
  • The vaccines were internally mutated after the tOPV had been ingested.
  • In 2017 three separate cVDPV2 outbreaks have occurred. Two outbreaks in the Democratic Republic of the Congo and the other outbreak in Syria.
  • These came from an immunisation with tOPV or infection from the excretions of other persons who had been vaccinated.
  • Those affected cannot be cured but immunisation in the vicinity raises the level of herd immunity and contains further spread.
  • The use of tOPV was stopped in May 2016 in favour of using bi valent OPV (bOPV) which has no attenuated WPV2 virus. (Only attenuated WPV1 and WPV3 viruses.)
  • The intention is to phase out bOPV and replace it with the inactivated polio vaccine (IPV).
  • The cost of IPV is much higher than OPV and also carries much greater immunisation requirement as it needs to be injected so the vaccinators need to be medically trained.
  • There are IPV manufacturing problems and it may not be until 2018 that supplies can be guaranteed.

I hope this explanation is helpful to you.

27 July 2017

Reg Ling
Rotary Club of Chandler's Ford and Itchen Valley.
Rotary District 1110 (Central Southern England and the Channel Islands).
Rotary Zone 18A (Southern England and Gibraltar) End Polio Now Coordinator (EPNC).    
Rotary Zone 18A (Southern England and Gibraltar) End Polio Now Coordinator (EPNC).

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