Update on Polio Eradication 2018

Posted by Dr. Paul Nelson
Update on Polio Eradication 2018
You have heard this before but we really are on the brink of eradicating polio, a disease that causes incurable paralysis.  There has only been one other disease, small pox, that has been completely stopped through vaccinations. Approximately 30 years ago, in 1988, Rotary accepted the challenge of eradicating Polio in the world with its partners World Health Organization, UNICEF, CDC (Centers for Disease Control). The Bill and Melinda Gates Foundation has accepted the challenge as well, joining Rotary’s fight.
If all the children in the world could be given the polio vaccine this disease could be eradicated, but this appears to be a very big job, and there appears to be some very big roadblocks, such as civil wars and political unrest, which have interfered with immunization programs.   The country of India proved that this can be done. This was a country that had much poverty and overcrowding. Now it has been 6 years without a case of paralysis from polio in India.  They accomplished this by having frequent immunization days (as often as every 2 weeks) in some of the difficult areas of the country, which resulted in at least 90% of the children being immunized against polio.
  • In 2016, there were 37 cases of paralyzing polio in the world
  • In 2017, there were only 20 cases!
  • But!  For each case of paralysis there are 199 other children who are infected without significant symptoms who could spread polio to an unimmunized playmate.
That’s why we can’t stop immunizing now, even though we’ve made so much progress and, as you’ve heard Bill Gates say, “We’re this close” to eradicating Polio.
Keep up the good work! Your contributions have done so much already. We can’t stop now. Remember, the Bill Gates Foundation will match your contribution 2:1.
For more information about Rotary’s fight against Polio, go to:
Reports show only 20 cases of paralysis from the wild polio virus this year compared to 37 cases in 2016, which is causing people to say “we are this close” to eradicating polio.  However, this year there were also 74 cases of paralysis reported in Syria and 12 cases reported in the Republic of the Congo.  These were not from the wild polio virus, but from the Vaccine Derived Polio Virus.
What is Vaccine-Derived Polio?  
The oral polio vaccine (OPV) contains an attenuated (weakened) vaccine-virus which activates an immune response in the body.  When a child is immunized with OPV, the weakened vaccine-virus replicates in the intestine for a limited time, thereby causing the child to develop immunity by building up antibodies.  During this time, the vaccine-virus is also excreted.  In areas of inadequate sanitation, this excreted vaccine-virus can spread in the immediate community (and this can offer protection to other un-immunized children through passive immunization), before eventually dying out.  On rare occasions, if a population is seriously under-immunized, an excreted vaccine-virus can continue to circulate (in un-immunized children) for an extended period of time.  The longer it is allowed to survive, the more genetic changes it undergoes.  In rare instances the vaccine-virus can change into a form that can cause paralysis.  This is what is known as a circulating vaccine-derived poliovirus (cVDPV). This is rare (about one in a million) and it takes a long time (at least 12 months) for a cVDPV to occur.  So the problem is not with the vaccine itself, but low vaccination coverage.  The risk of this occurring is very slight and pales in significance when compared to the tremendous health benefits associated the OPV.  If a population is fully immunized they will be protected against both vaccine-derived and wild polioviruses. 
What can be done about Vaccine-Derived Polio?                                                                                  
 In the past circulating VDPVs have been rapidly stopped with 2-3 rounds of high-quality immunization campaigns.  Over 90% of cVDPV cases were due to the type 2 component in OPV, and because there had not been a case of paralysis from Wild type 2 virus since 1999 a switch was made in April 2016 from the trivalent OPV to bivalent OPV (eliminating type 2) which has removed the risk of cVDPV2.
How close are we, then, to completely stopping polio in the world ?                                         
Type 2 Wild Polio Virus was eradicated in 1999. There has not been a case of paralysis from Type 3 Wild Polio Virus found anywhere in the world since 2012  Only three countries in the world remain—Afghanistan, Pakistan and Nigeria--where polio is endemic. But environmental tests (on sewage) in these countries continue to be positive for Type 1 poliovirus. Recognizing both the opportunity of eradicating polio and the significant risks of possible failure, the plan “The Polio Eradication and Endgame Strategic Plan 2013-2019” was developed by the Global Polio Eradication Initiative (GPEI) of the World Health Organization.  This plan addresses all aspects of polio eradication and exploits the unique opportunity to stop all polio disease once and for all.  It also builds on new tactics and progress on interrupting wild poliovirus transmission and the development of new tools and strategies for managing the risks of vaccine-derived poliovirus.  
The goal continues to be that no child will ever again suffer the terrible effects of life long polio-paralysis.