Some types of the poliovirus are already eradicated! The polio case is exceedingly frustrating as it's been hindered by the Taliban, Boko Haram, and the likes with their stupid "this is a tool for massacre Muslims!!11" and similar rhetoric. It's not inconceivable Polio would already have need eradicated if it wasn't for that, and COVID didn't help either due to shifting priorities and such.
The good news is that the Taliban did a u-turn on this after taking over last year, and now vaccination efforts in Afghanistan are underway again. Small silver lining from the Taliban takeover I guess :-/
At any rate, current hopes for polio eradication seem to be for 2026[1], whereas Guinea worm is 2030.
The real vaccination campaign with alternate motives. Nobody who got a shot there wasn't vaccinated. That they also carried out surveillance was regrettable, because it did create a negative narrative, but the vaccines weren't fake.
“Fake” go with “campaign”, not “vaccine”. The vaccine was real, the campaign was fake: they run a surveillance campaign and incidentally vaccinate a few people, hence “fake vaccination campaign”
I guess the torture program was regrettable, too. Not regrettable enough to prosecute anyone, though. Or even to allow the UN to prosecute, or to allow anyone indicted (e.g. in Spain) to be extradited.
Allowing CIA to corrupt vaccination efforts is better described as a disastrous debacle.
No, that's not the biggest problem. The biggest problem is cVDPV2 (i.e. vaccine derived type 2 Polio). Type 2 Polio is extinct in the wild, but the vaccine derived version refuses to stop.
The trouble is the only way to stop cVDPV2 is to immunize for it - but that same immunization is what creates cVDPV2 in the first place.
Until a better vaccine arrives, it doesn't look like we'll ever eradicate it, Taliban etc aren't changing that. However there might be good news:
"March 2021 saw the first use of the modified nOPV2 vaccine in selected countries. This was engineered to allow vaccination against strain 2 poliovirus without the frequent spawning of cVDPV2 seen with the original OPV2. Full rollout was not expected until 2023."
I was under the impression that vaccine derived polio would eventually fizzle out after the entire population becomes vaccinated (i.e. "herd immunity")?
That was the idea - but it failed. Type 2 does not exist in the wild, it's all from vaccine derived. It got so bad they stopping giving type 2 vaccine, but then people have no immunity to the vaccine derived version - but if you give the vaccine, then the vaccine causes more cases (of type 2) than it's stopping.
There's no solution here - either option makes things worse.
So I hope the new version of the vaccine works, because otherwise this will fail.
Type 3 appears basically extinct - both in the wild, and vaccine derived. Only type 1 still exists in the wild, and vaccine derived type 2.
> if you give the vaccine, then the vaccine causes more cases (of type 2) than it's stopping.
> There's no solution here - either option makes things worse.
That's false and misleading. The OPV2 vaccine will stop both vaccine-derived cvdpv2 virus from spreading and the wild type 2, which has been eradicated. Since OPV2 is a live attenuated virus, it will also continue to multiply and confer protection to any person drinking contaminated water, the vaccine "spreads". It is thus highly effective at stopping polio and in no way it can be said that it "causes more cases than it's stopping".
The problem with OPV2 is that it has a relatively higher chance of reverting to an variant that causes polio. This is not a problem if the population has a high level of vaccination, since the live attenuated virus cannot propagate and mutate. It's only problematic in low coverage areas where it can multiply extensively in many hosts.
Thus, the cvdpv2 epidemic is an expression of low vaccination rates, similar in every way to a wild poliovirus resurgence. The novel OPV2 vaccine will improve the genetic stability of the attenuated virus, allowing further "viral vaccinations" in low coverage areas - but we could eradicate cvdpv2 today with the existing OPV2 vaccine, if only we could get good vaccinations rates everywhere, as it has happened in most of the world.
You are completely misinformed about this. I spent quite a long time reading about this.
What you write is what they hoped would happen. However it did NOT happen. The reason is that the more you try to vaccinate the entire population, the more cases of cvdpv2 you cause. Until you hit that magic 100% you cause more harm than you prevent.
And in the real world 100% is impossible. So yes opv2 "causes more cases than it's stopping" - there are zero cases of wild type 2, so it's stopping nothing except itself.
And in fact that people running this campaign noticed this and stopped vaccinating with opv2! (Which perhaps you did not know.)
The new version of it will hopefully help, and we can eradicate this.
But right now Polio eradication is failing, not because of Taliban, but because of cvdpv2.
I have high hopes for the new version, but it'll be years before we know.
> The reason is that the more you try to vaccinate the entire population, the more cases of cvdpv2 you cause. Until you hit that magic 100% you cause more harm than you prevent.
This makes little sense if you understand that both wpv2 and cvdpv2 were eliminated in the poorest regions of the world using OPV2. If what you claim is true, elimination would have been impossible, you would simply replace wpv2 with cvdpv2, since any attempt at eradication would seed new cvdpv2 cases.
Inactivated injectable vaccine, which does not boost herd immunity, is inefective in these countries with limited health systems.
> And in fact that people running this campaign noticed this and stopped vaccinating with opv2! (Which perhaps you did not know.)
Perhaps you refer to the global coordinated action to move from trivalent vaccine to bivalent (wpv1+ wpv3) in 2016 after the wild type 2 virus was certified as eradicated. But monovalent OPV2 was still being used recently to target specific areas where cvdpv2 is endemic. It makes little sense to use it elsewhere and seed cvdpv2.
And 8 years later the vast majority of Polio in the world is cvdpv2. (There is more cvdpv2 then wild type 1 and 3 combined.)
You are correct in your details, but are completely missing the bigger picture.
If you look at stats there is zero evidence that cvdpv2 is going away, it just shifts countries, goes up, goes down, but has no signs of ending.
If not for the new vaccine (and I hope it works), cvdpv2 indicates the failure to eradicate Polio. The new vaccine may change the picture, we shall see in about 2 years.
Right now the Taliban is not the biggest obstacle to Polio eradication, cvdpv2 is. And if you check my comments this has been my claim from the start, so I'm not sure what you are arguing against.
Just because vaccines are great, doesn't mean they are perfect, it's not necessary to reflexively defend them.
There have been dozens of cVDPV outbreaks that have been successfully contained in countries around the world. We know how to do it even with our existing vaccines. These outbreaks don’t just come and go at random, they happen in places with inadequate vaccination and are eliminated using a proven playbook.
New vaccines will make the process smoother and faster, but we’re certainly not at a dead end without them.
I feel like you keep missing the point. Why are there still outbreaks 6 years later? (Answer: Because we keep causing the outbreaks.)
Is the plan to just keep vaccinating forever? Doesn't that mean that eradication failed? Wild type 2 is extinct, so why are we still fighting it? (Answer: Because we are fighting our own actions.)
> We know how to do it even with our existing vaccines.
You sure? Because it sure doesn't look like success from here.
> they happen in places with inadequate vaccination
If that were true why the switch to bivalent? How can you have "adequate" vaccination when we are not even vaccinating in the first place?
> and are eliminated using a proven playbook.
That's exactly the problem - they do not get eliminated. All we are doing is keeping outbreaks from getting huge, by creating small outbreaks.
This new vaccine is a complete game changer, not the incremental step you think it is.
Where did you get these outlandish expectations of how much progress would have been made by now? The plan, above all else, was and is to eliminate wild polio virus. Even in the best case scenario, we’re still 5-10 years away from being able to declare it extinct, so you should expect the OPV is still going to be in use until then, and the risks of vaccine-derived polio will still have to be managed for a long time to come. Unfortunately not every country have done a perfect job of that, but it certainly is possible, as demonstrated by the majority of the world having zero cases.
I think 'ars' is leading you into a rhetorical trap. The objective was never eliminating the wild virus, the objective was curing polio. The OPV vaccine is a bit like fighting fire with fire: you burn down the forest (immunize susceptible hosts) in a controlled fashion, so that the forest fire cannot reach homes (paralyze children). But when your house burns down, it's irrelevant if it was the "wild" fire or a fire set by the firefighters, i.e a attenuated virus that mutated.
What 'ars' seems to be missing is that this particular "forest" is very rapidly growing back, in some countries you have in excess of 5% of the population as infants each year. Those are new hosts that were never vaccinated, and due to the extreme contagiousness of the disease a few years of lack of coverage can reignite the fire. What happened after OPV2 withdrawal was that a whole new generation inoculated with only bivalent (type 1+3) vaccine became susceptible to cvdpv2 that was still circulating in small pockets.
Essentially, the campaign failed the end-game strategy, they proved they can reduce the infection to arbitrarily low levels using trivalent OPV, but once you take OPV away, as they attempted for a single strain, the epidemic reignites. It's irrelevant if it's a wpv or cvdpv strain. The end-game was always considered a challenge by experts, but a variety of reasons, Covid, political issues etc. conspired to make it very difficult.
This whole thread leaves me very pessimistic about the prospects of eradication. If a relatively inteligent and educated internet-person that has proper sanitation cannot understand these epidemiological dynamics and claims that "OPV causes more infections than it cures", what's the chance you can explain it to rural farmers, especially after the global rise of the antivax movement after Covid?
OPV2 (specifically 2) cures zero infections because type 2 is extinct in the wild. If causes some infections.
So explain how my sentence isn't true?
A decade ago when type 2 was in the wild, OPV2 was very valuable. Today though it's the greatest obstacle to eradication (and not because people are doing something bad, it's just unfortunate circumstance).
> OPV2 (specifically 2) cures zero infections because type 2 is extinct in the wild. So explain how my sentence isn't true?
OPV2 prevents cvdpv2 infections. This is a virus similar in all respects to wpv2, except its lower rate of paralysis onset. It's effectively the same disease, just like in my forest fire analogy.
Before the advent of nOPV2, OPV2 was much more effective at this than any other option. So you could not simply cease OPV2 production, post 2016 it was targeted to cvdpv2 hotspots only.
The thing is that we really, really want to be able to stop giving the OPV vaccine because - aside from the fact that it requires a bunch of resources and there's always the risk of disruptions to vaccination from civil wars, other pandemics, etc - the original unmutated vaccine itself paralyzes and even kills a small fraction of the people it's given to, and at low levels of disease those cases can easily become more common than actual polio-related paralysis. That's why it's not used in the developed world anymore.
IIUC the idea is to mix the oral vaccine with attenuated virus with only the types 1 and 3, and the injectable vaccine with inactive virus with the types 1, 2 and 3. https://en.wikipedia.org/wiki/Polio_vaccine#Schedule So you have coverage for the three types.
(It's more complicated. For example country without recent cases and good vaccine coverage only use the injectable vaccine.)
The problem is that although the inactivated vaccine provides good protection against severe polio it doesn't seem to work too well at stopping people from spreading the virus, which is not ideal for an elimination program. Presumably this was less of an issue in the developed world because polio spreads mostly through the oral-fecal route and there were already a lot of hygene and infrastructure improvements in developed countries aimed at stopping diseases from spreading that way.
