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Polio eradication program faces hard choices as endgame strategy fails:
The "endgame" in the decades-long campaign to eradicate polio suffered major setbacks in 2019. While the effort lost ground in Afghanistan and Pakistan, which recorded 116 cases of wild polio—four times the number in 2018—an especially alarming situation developed in Africa. In 12 countries, 196 children were paralyzed not by the wild virus, but by a strain derived from a live vaccine that has regained its virulence and ability to spread. Fighting these flare-ups will mean difficult decisions in the coming year.
The culprit in Africa is vaccine-derived polio virus type 2, and the fear is that it will jump continents and reseed outbreaks across the globe. A brand new vaccine is now being rushed through development to quash type 2 outbreaks. Mass production has already begun, even though the vaccine is still in clinical trials; it could be rolled out for emergency use as early as mid-2020. At the same time, the Global Polio Eradication Initiative (GPEI) is debating whether to combat the resurgent virus by re-enlisting a triple-whammy vaccine pulled from global use in 2016. That would be a controversial move, setting back the initiative several years, as well as a potential public relations disaster—an admission that the carefully crafted endgame strategy has failed.
"All options are on the table," says viro-logist Mark Pallansch of the U.S. Centers for Disease Control and Prevention, one of the five partner organizations in GPEI. "We are clearly in the most serious situation we have been in with the program," adds Roland Sutter, who recently stepped down as the director of polio research at the World Health Organization (WHO).
The heart of the problem is the live oral polio vaccine (OPV), the workhorse of the eradication program—the only polio vaccine powerful enough to stop viral circulation. Given as two drops into a child's mouth, OPV for decades contained a mix of three weakened polio viruses, one for each of the three wild serotypes that have long plagued humanity. All three serotypes in the vaccine have the potential to revert to more dangerous versions; that's why the endgame strategy calls for deploying OPV in massive campaigns to eradicate the wild virus, then ending its use entirely.
Wild serotype 2 was last sighted in 1999, so in 2016, as a first step in the endgame, all 155 countries using OPV replaced the trivalent version with a bivalent one, lacking the type 2 component. Announced with great fanfare, "the switch" was billed as the biggest vaccine rollout ever. Some type 2 outbreaks would inevitably occur for several years, GPEI realized, but those would be fought, somewhat paradoxically, by rushing in essentially the same vaccine that gave rise to them in the first place: a live, monovalent vaccine targeted against type 2 (mOPV2). If used in well-run campaigns, and only in outbreak regions, mOPV2 could stop outbreaks without seeding new ones, models suggested.
It often has not turned out that way. Instead of fading away, the number of type 2 outbreaks in Africa almost tripled from 2018 to 2019. Most of today's outbreaks stem from mOPV2 responses to previous ones, and GPEI is burning through its emergency stockpile of mOPV2 faster than it can be replenished. (Based on a small study in Mozambique, a WHO advisory panel recently recommended halving the dose to one drop if supplies run critically low, despite what it calls "a relatively weak level of evidence" that the smaller dose is as effective.) Meanwhile, the risk of explosive outbreaks around the globe is ratcheting up, because millions of children born since the switch have little or no immunity to type 2 virus.
(Score: 0) by Anonymous Coward on Wednesday January 01 2020, @04:52PM (5 children)
"Most of today's outbreaks stem from mOPV2 responses to previous ones, and GPEI is burning through its emergency stockpile of mOPV2 faster than it can be replenished."
So wait, am I understanding this correctly? We are responding to a problem and our response just keeps making the problem worse?
I did a little Googling
"Destroy the virus blueprint (or genes) so that the virus can’t replicate at all. This is how the “killed” polio vaccine (or polio shot) is made. Vaccine virus is made by treating polio virus with the chemical formaldehyde. This treatment permanently destroys the polio genes so that the virus can no longer replicate."
http://www.pkids.org/immunizations/how_they_work.html [pkids.org]
But I suppose the proteins with no DNA is not enough in this situation to give strong immunity (or so I thought?)?
This Wikipedia article seems useful.
"When the IPV is used, 90% or more of individuals develop protective antibodies to all three serotypes of polio virus after two doses of inactivated polio vaccine (IPV), and at least 99% are immune to polio virus following three doses. The duration of immunity induced by IPV is not known with certainty, although a complete series is thought to provide protection for many years."
"Oral polio vaccines proved to be superior in administration, eliminating the need for sterile syringes and making the vaccine more suitable for mass vaccination campaigns. OPV also provided longer-lasting immunity than the Salk vaccine, as it provides both humoral immunity and cell-mediated immunity.[medical citation needed]
One dose of OPV produces immunity to all three poliovirus serotypes in roughly 50% of recipients.[17] Three doses of live-attenuated OPV produce protective antibodies to all three poliovirus types in more than 95% of recipients. "
https://en.wikipedia.org/wiki/Polio_vaccine#Inactivated [wikipedia.org]
So if I'm reading this correctly it seems that the IPV version is at least just as effective as the live version but the live version is more convenient to administer, possibly cheaper (since they don't need new syringes each dose or at least they don't need to sterilize them) and hence poses less of a risk of getting infected with something else by the use of a recycled syringe.
So they wanted a quick scheme to eradicate the polio virus completely. They found the cheap way out with the plan of not using it anymore once it worked because of the dangers involved but instead it just made things worse costing more money in the long run. Instead of spending more money up front to do it the more expensive way at first saving them money and headaches in the long run. Is this correct? Am I missing something?
(Score: 0) by Anonymous Coward on Wednesday January 01 2020, @04:56PM (3 children)
Also it notes that the live version provides longer immunity. So perhaps repeat doses of the inactivated form after five or ten years. Again, more cost up front but less cost later down the line.
(Score: 0) by Anonymous Coward on Wednesday January 01 2020, @05:10PM (1 child)
Don't look too much into polio vaccinations if you do not want to be seriously disturbed. The same guy who started the anti smoking crusade publically injected his daughter and grandson (after being warned it was going to cause polio) to prove it was safe. One died and the other became paralyzed within a week. He suffered no loss of reputation for this error in judgement.
Then there are the various viruses known to cause cancer and obesity that have been discovered to contaminate the vaccines over the years.
(Score: 0) by Anonymous Coward on Thursday January 02 2020, @05:49PM
Um, no. Dumbass.
It's known that OPV can induce polio at a rate of infection far far FAR less than wild versions. The rest of what you say is just bullshit.
(Score: 2, Interesting) by Anonymous Coward on Wednesday January 01 2020, @05:26PM
https://www.nytimes.com/1955/05/05/archives/bulbar-polio-kills-doctors-grandson.html [nytimes.com]
(Score: 0) by Anonymous Coward on Thursday January 02 2020, @05:42PM
Yes, you're missing a bit of the economics of what it takes to fight viruses. OPV is considerably cheaper per dose than IPV. That's the only thing OPV has going for it.
It can still be used because all the math says that the number of vaccine-induced polio cases from OPV is far, far fewer than what it would be with wild transmission. (But countries like the United States, which can afford the cost, does not use OPV at all anymore and only uses IPV).
The article seems to fail to consider the possibility that the real answer is that the time has come to switch over the world to IPV and stop using OPV at all.