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I was surprised too, but the WHO backs up the existence of "vaccine-associated paralytic polio", though I'm finding some conflicting numbers it's on the order o

by tgb 6y ago

I was surprised too, but the WHO backs up the existence of "vaccine-associated paralytic polio", though I'm finding some conflicting numbers it's on the order of 1 in a million paralysis cases per vaccine. That presumably outpaces wild polio paralysis cases due to the non-existence of wild polio, in certain regions. WHO evens says it's possible for others to catch the paralysis from close contact with a recently-vaccinated individual, though it's never spread beyond that. https://www.who.int/immunization/diseases/poliomyelitis/endgame_objective2/oral_polio_vaccine/VAPPandcVDPVFactSheet-Feb2015.pdf https://www.who.int/immunization/diseases/poliomyelitis/endg...

nsgi 6y ago
cVDPV is the one that's the big problem. You can see how many cases are occurring here: http://polioeradication.org/polio-today/polio-now/this-week/ http://polioeradication.org/polio-today/polio-now/this-week/
makomk 6y ago
There are two similar but crucially different problems with the current live polio vaccine that both end in cases of paralytic polio. Vaccine-associated paralytic polio is a very rare complication where someone gets full-on paralytic polio as a result of being vaccinated; it can also happen to people who catch the vaccine virus from someone else rather than from vaccination, but it's just as rare there. Circulating vaccine-derived poliovirus is the one that's really nasty for elimination efforts - once the vaccine poliovirus circulates unchecked within a community for a while, it mutates and basically turns back into full-on real, unweakened polio in all its contagious paralytic awfulness, at which point anyone who's exposed to it is at much higher risk. As I understand it, cVDPV makes up the large majority of both polio cases and paralytic polio cases across the globe these days, and 100% of cases in Africa now the wild-type virus has been eliminated from there. If VAPP was the only problem it could easily be fixed just by eliminating polio and then ending the live vaccination program. Unfortunately, that would make the cVDPV problem worse because it's an actual, circulating virus that primarily infects people who haven't been vaccinated, and ending vaccination would increase the number of people at risk from it. As the document from 2015 you've found suggests, the folks trying to eliminate polio hoped that if they phased out the live oral polio vaccine carefully and in well-coordinated ways they could avoid major cVDPV outbreaks afterwards. This doesn't seem to have worked out as well as they hoped back then. In particular, this article and HN discussion from a few months ago which someone helpfully dug up is mostly about the failure of this endgame plan in Africa: https://news.ycombinator.com/item?id=21920406 https://news.ycombinator.com/item?id=21920406

by tgb 6y ago

nsgi 6y ago

cVDPV is the one that's the big problem. You can see how many cases are occurring here: http://polioeradication.org/polio-today/polio-now/this-week/ http://polioeradication.org/polio-today/polio-now/this-week/

makomk 6y ago

There are two similar but crucially different problems with the current live polio vaccine that both end in cases of paralytic polio. Vaccine-associated paralytic polio is a very rare complication where someone gets full-on paralytic polio as a result of being vaccinated; it can also happen to people who catch the vaccine virus from someone else rather than from vaccination, but it's just as rare there. Circulating vaccine-derived poliovirus is the one that's really nasty for elimination efforts - once the vaccine poliovirus circulates unchecked within a community for a while, it mutates and basically turns back into full-on real, unweakened polio in all its contagious paralytic awfulness, at which point anyone who's exposed to it is at much higher risk. As I understand it, cVDPV makes up the large majority of both polio cases and paralytic polio cases across the globe these days, and 100% of cases in Africa now the wild-type virus has been eliminated from there. If VAPP was the only problem it could easily be fixed just by eliminating polio and then ending the live vaccination program. Unfortunately, that would make the cVDPV problem worse because it's an actual, circulating virus that primarily infects people who haven't been vaccinated, and ending vaccination would increase the number of people at risk from it. As the document from 2015 you've found suggests, the folks trying to eliminate polio hoped that if they phased out the live oral polio vaccine carefully and in well-coordinated ways they could avoid major cVDPV outbreaks afterwards. This doesn't seem to have worked out as well as they hoped back then. In particular, this article and HN discussion from a few months ago which someone helpfully dug up is mostly about the failure of this endgame plan in Africa: https://news.ycombinator.com/item?id=21920406 https://news.ycombinator.com/item?id=21920406