Progress in Eradicating Polio
The number of cases of Polio world wide has continued to drop and in 2016 there were only 37 cases of Wild Polio Virus (Afghanistan 13, Nigeria 4, Pakistan 20) and 5 of the circulating Vaccine Derived Polio Virus. (Lao 3, Nigeria 1, Pakistan 1).
This map (dated February 15th) shows the distribution of all of the cases worldwide in 2016 plus the 1 case to date for 2017.
This map shows in more detail, the location of cases in Pakistan and Afghanistan. As always, most of the cases in 2016 were close to the border between the two countries. Up-to-date details can be found here.
Although the last case of Polio in India was in 2011, there is still great concern that unless India continues to take extreme precautions, Polio might either reappear or slip over the border from the remaining two major countries where it is still endemic.
India’s plan for the post polio world includes:
- in April 2016, switching from an oral polio vaccine (OPV) designed to combat three types of wild polio virus (known as trivalent OPV) to one designed for two types of wild polio virus (known as bivalent OPV). This is because Type 2 Polio Virus has not been seen for many years and is therefore said to have been eradicated.
- introducing (the injected) Inactivated Polio Vaccine (IPV) from 2015 with a target of totally replacing OPV with IPV in 2018/19.
One of the problems of using OPV is that because it is a live (but very attenuated) vaccine, there is a risk of Vaccine Derived Polio Virus being a source of Polio in the community.
India has an ambitious plan to make immunisation of all children at birth and then during their early years, the norm. Children will be immunised with BCG, HepB and Poliovirus at birth, and then Diphtheria, Tetanus, Whooping Cough, Hib, Pneumonia and Rotavirus at 6 weeks plus many more vaccinations in the coming months and years - essentially a programme which is regarded as the norm in many other countries.
Currently more than 26 million children are born In India each year and Unicef estimate that infant deaths in India comprise some 20% of the world total, a figure which routine immunisation will help to reduce.
However as at January 2017, the current level of Routine Immunisation is 65% in the better areas and considerably less in the worse areas, far short of the generally accepted 95% required to achieve “herd immunity” (see also here for an explanation). So it is mainly for this reason, that National Immunisation Days with live Oral Polio Vaccine are likely to continue certainly into 2018 and maybe into 2019.