Polio
WHO Eradication
[http://rstb.royalsocietypublishing.org/content/368/1623/20120140.full The final stages of the global eradication of poliomyelitis (2013)]
- serotype 2 gone - out-competed 1 & 3 in trivalent
- now mono/bivelant to get 1 & 3
- several vaccinations often necessary to get immune response
- can have 100 infected & only 1 AFP showing - less obvious than smallpox
OPV
1988: Safety of OPV: results of a WHO enquiry
Acute persistent spinal paralysis (APSP)
Risk normally less than 0.3 per million dses
But one countery higher: 6 per mission
India
Strategy
National Immunization Days (NIDs):
Conduct Pulse Polio Immunization (PPI) programme by providing additional OPV doses to every child aged <5 years at intervals of 4-6 weeks. The aim of NIDs/PPI is to “flood” the community with OPV within a very short period of time, thereby interrupting transmission of virus throughout the community. Intensification of the PPI programme is accomplished by the addition of extra immunization rounds, adding a house-to-house “search and vaccinate” component in addition to providing vaccine at a fixed post. The number of PPI rounds conducted during any particular year is determined by the extent of poliovirus transmission in the country. In recent years, several rounds have been conducted throughout the year – especially in the northern states of Uttar Pradesh and Bihar, which have carried a heavier burden of poliovirus – in an attempt to break the last chains of transmission. Intensification of PPI requires meticulous programme planning, intensive supervision and monitoring and extensive social mobilization.
2007: Discontents
Polio eradiction in India: the way forward
Problem With Over-Vaccination?
Actual Paper: "Polio programme: let us declare victory and move on"
The paper is about how elimination has been pursued too exclusively, resulting in over-administration of the vaccine (and hence complications) where a more nuanced control-focused strategy including efforts on sanitisation as well as routine immunisation could have been more effective. Alleges 47,500 extra paralysis cases in one year alone.
"From India’s perspective the exercise has been extremely costly both in terms of human suffering and in monetary terms. It is tempting to speculate what could have been achieved if the $2.5 billion spent on attempting to eradicate polio were spent on water and sanitation and routine immunisation. Perhaps control of polio, to the level of elimination, may well have been achieved as it has been in more developed countries."
However the side-effects appear to be arising because the areas of India in question are over-vaccinating way beyong the recommended levels. Too much money being chucked at the problem, with inadequate control perhaps?
I agree that "herd immunity" isn't some kind of a magic wand that makes everything lovely. I don't personally think "herd immunity" is a very useful term much of the time, because it represents a state of affairs that may not be practically reachable on a whole-population basis. I believe smallpox got knocked out by targetted vaccinations around cases, not trying to vaccinate the entire population of the world.