Why smallpox is no more, but polio and other diseases persist | Hacker News Reader

Why smallpox is no more, but polio and other diseases persist

quantamagazine.org

86 pointsyarapavan52 comments

<the laboratory-weakened virus used in the oral polio vaccine can very rapidly regain its strength if it starts spreading on its own.

After a child is vaccinated with live polio virus, the virus replicates inside the child's intestine and eventually is excreted.

In places with poor sanitation, fecal matter can enter the drinking water supply and the virus is able to start spreading from person to person.

"We discovered there's only a few [mutations] that have to happen and they happen rather quickly in the first month or two post-vaccination," Andino says.

"As the virus starts circulating in the community, it acquires further mutations that make it basically indistinguishable from the wild-type virus.

It's polio in terms of virulence and in terms of how the virus spreads."

In June, the World Health Organization reported 15 cases of children paralyzed in Syria by vaccine-derived forms of polio.

These cases come on top of two other vaccine-derived polio cases earlier this year in Syria and four in the Democratic Republic of the Congo.>

https://www.npr.org/sections/goatsandsoda/2017/06/28/5344030...

Wild-type polio could very well be gone by now if the CIA hadn’t burned Western doctors’ goodwill in Pakistan by using fake polio vaccines to take DNA from children suspected to be related to Osama bin Laden.

This isn’t close to the most evil thing the CIA has done, but it makes me the most unreasonably angry.

What the hell. This sounds comically villainous. On the other hand we _are_ talking about the CIA here. Got a link?

https://www.scientificamerican.com/article/how-cia-fake-vacc...

The CIA have crafted a wonderful brand: with their actions, they've created a (truthful) universal public image that they'd stoop to the southern tip of Hell to get whatever they want, completely numbing the public to any possible action. If the CIA had a good reputation, hearing something like "They undermined public faith in vaccines, leading to multiple modern-day problems and epidemics" would lead to skepticism, and then riots.

Instead, we all know the substance of the agency's actions, and of the character of its men. As a result, we're mildly surprised when we hear this, and don't feel it's a substantial deviation from the status quo.

couldn't they have done both at the same time though?

take DNA and give them vaccine.

The point is that now people in that part of the world think doctors are CIA agents and try to kill them.

Not just that part of the world.

This was an issue during the last Ebola epidemic. And it may impede a vaccination program.

Here’s a more interesting dilemma, one which I could hardly believe once I heard it:

> More Polio Cases Now Caused by Vaccine Than by Wild Virus

If that’s true, at what point do we stop vaccinating for it?

1. https://www.nytimes.com/aponline/2019/11/25/health/ap-af-med...

2. https://www.npr.org/sections/goatsandsoda/2017/06/28/5344030...

To be clear, it's the cheap, oral, live virus polio vaccine that's causing the problem.

They don't use that in the US, at all, and we don't have the issue.

We don't need to stop polio vaccination...we need to find a reasonable way to replace the low budget version.

I don’t know why you are being downvoted, what you said is entirely correct AND cuts through the confusion. People need to realize that there are different Polio vaccines and the original Salk vaccine has zero chance of infecting people with Polio.

I downvoted because it’s not correct to suggest that OPV is being used because it is a “low budget version”. In fact, both types of vaccines are being given to children in high-risk countries, as part of the transition away from the live vaccine.

In countries with endemic polio or where there is a high risk of imported cases, the WHO recommends OPV vaccine at birth followed by a primary series of 3 OPV and at least one IPV doses starting at 6 weeks of age.

https://en.m.wikipedia.org/wiki/Polio_vaccine

"The IPV that has been used in the United States since 1987 is as effective as OPV for preventing polio"

https://www.cdc.gov/vaccines/vpd/polio/public/index.html

"Unfortunately, IPV costs considerably more than OPV per dose ($3-5 vs $0.12 on the subsidized world market). Because the WHO and most countries have plans to continue vaccination for at least 10 years after eradication, there will continue to be a market for the vaccine. Because of the high cost of the IPV, efforts are underway to derive improved and less expensive IPV vaccines."

http://grantome.com/grant/NIH/R44-AI120260-02

"One hundred twenty-six low- and middle Income countries will start to use IPV, which is injected, in a single dose, in addition to the oral polio vaccine (OPV). OPV will gradually be phased out, based on certain epidemiologic triggers.

The previous price was a major barrier to making this shift. The shift is needed because, for eradication to occur, the polio virus needs to be gone from people, labs, sewage, etc. – i.e. the places in which vaccine-derived polio virus can survive, mutate and cause disease. IPV is ‘inactivated’, and does not carry risk of polio infection to people who are not vaccinated."

https://blogs.unicef.org/blog/lowest-ever-prices-for-polio-v...

The WHO only recommends OPV because of the low cost.

IPV induces very low levels of immunity in the intestine. As a result, when a person immunized with IPV is infected with wild poliovirus, the virus can still multiply inside the intestines and be shed in the faeces, risking continued circulation.

“...as IPV does not stop transmission of the virus, OPV is used wherever a polio outbreak needs to be contained, even in countries which rely exclusively on IPV for their routine immunization programme. Once polio has been eradicated, use of all OPV will need to be stopped to prevent re-establishment of transmission due to VDPVs.”

http://polioeradication.org/polio-today/polio-prevention/the...

well it is correct: "But the injectable polio vaccine (IPV) is a better way to inoculate children against the disease: it is safer because it does not carry the live virus. Unhappily, it is also more expensive." https://www.economist.com/feast-and-famine/2013/07/19/inject...

Still, now that price has dropped to less than $1 per dose, I am sure rich governments or simple rich people can foot the bill.

Yes, it’s true that OPV is cheaper, but it will continue to be used because it is more effective at preventing the transmission of wild polio virus.

http://polioeradication.org/polio-today/polio-prevention/the...

There were more cases of OPV caused polio than wild polio in 2019.

Maybe it's useful still in Pakistan and Afghanistan. Everywhere else should switch if it's viable economically to so so.

Good news: https://www.gavi.org/news/media-room/inactivated-polio-vacci...

The live vaccine is not simply a “low budget version”, it’s more effective.

It is not.

There's a number of reasons the live polio vaccine is preferred in developing countries. The biggest is that the OPV vaccine, as the name suggests, is oral. You don't need needles, which means it's easier to mass administer, you don't have to deal with sharps, etc. I think people vastly underestimate the logistical difficulties of delivering vaccines, especially injectables that require a cold chain like IPV.

It also sheds, which is good if you're struggling with vaccine coverage. Whether this is a downside or not is a highly dynamic question - as we get closer, the side effects become a bigger deal, but part of the reason they're a big deal is because WT polio is so heavily suppressed.

See this link: https://en.wikipedia.org/wiki/Attenuated_vaccine#Advantages

Advantages of an attenuated vaccine:

- Activates all phases of the immune system

- Provides more durable immunity; boosters are required less frequently

[other are mainly logistics]

The disadvantage is that it may cause a reversion to virulence in 3 per 1 000 000 doses given. And it cannot be used in immunocompromised individuals.

That's the truly nasty part of this dilemma: we can't stop vaccinating for it. People who haven't been vaccinated are most at risk of being infected due to the polio vaccine, since the vaccine-derived strains spread from person to person just like the wild polio that they almost eliminated and become more dangerous as they do so. In order to keep those infections under control people are being vaccinated on a massive scale, which works in the short term but spreads massive amounts of the vaccine poliovirus which will cause infections further down the line. The injectable polio vaccination might offer a solution since it uses a dead virus that can't cause an actual infection, but there's just not the infrastructure to treat eveyone with it.

Read the recomendad schedule by WHO in https://en.wikipedia.org/wiki/Polio_vaccine#Schedule

* For countries with endemic: case use a few doses of the oral vaccine (that is more powerful) and at least one dose of the injectable version.

* For countries without recent cases an a good vaccination coverage: A few injectable doses and later a few oral doses

* For countries with very good coverage and low risk of imported cases: Use only the injectable version (that don't cause vaccine derived infections)

When your country gets no case for a long enough time and you get a better vaccine coverage, you can "upgrade" the vaccination schedule.

(We changed the vaccination schedule a few years ago here in Argentina. Now it is injectable-injectable-oral-oral-oral.)

This answers a long-standing question I have had in the back of my mind: Why aren't oral vaccines more common?

I imagine it takes a more aggresive formulation to be effective orally, whereas injection is a straight shot into the fray of the immune system's war on pathongens. These more active forms seem to raise the risk of mutation to active virulence.

IANAMD. The polio virus usually attack the intestine, moreover it usually attack only the intestine and cause no symptoms.

The normal way of transmission is eating something that is contaminated with poop of an infected person. So it is probably easier to create a vaccine that can be "eaten".

Using the live vaccine is a trade-off, but there is clear roadmap to eliminate the need for it, one that requires coordinated global surveillance and decision-making.

The global strategy for all areas that have eradicated wild polio viruses is to switch from using OPV with live attenuated polio virus to IPV with the killed virus. On April 26, 2016, health authorities around the world implemented a global synchronous switch in which all trivalent oral polio stocks – containing all three strains of the virus – were destroyed to prevent any form of the live type 2 vaccine circulating again. Only a bivalent oral polio vaccine containing the live weakened type 1 and type 3 viruses has been used since then along with the trivalent IPV containing killed strains of all three types of viruses.

https://www.google.ca/amp/s/amp.scroll.in/pulse/910881/polio...

We have to make sure people can afford the original Salk vaccine (which is totally inert) instead of the dangerous oral replacement one invented decades later.

As is often the case it’s about affordability

It's also much easier to administer, which matters a great deal in many of these settings.

> If that’s true, at what point do we stop vaccinating for it?

We stop when we have a way to actually cure the disease or we create a society where people aren't living on top of each other.

Just like industrial farming requires mass vaccination and heavy antibiotic use due to high animal concentration, humans need to be vaccinated since industrial society requires massive concentration of people in urban areas.

In a 100 years, if medical science can identify vulnerable individuals or actually cure these diseases, we won't need mass vaccination. But until then mass vaccination is the only option. Current scientific knowledge doesn't allow us to keep tens of millions of people in a small area without vaccination.

Diseases were doing pretty well even before tens of millions of people were living in close proximity.

Sure. But diseases do even better when people are concentrated, especially infectious diseases which are the prime targets of vaccines.

We never stop vaccinating for it. If we stop, polio will resurge. It’s unfortunate that people get polio from the vaccine, but it’s worth it because everyone else who gets vaccinated can’t get polio.

Unless it is erradicated. Smallpox hasn't resurged yet, and we stopped vaccinating against it.

We stop when it's eradicated.

There’s no free lunch. Where do you draw the line? Or does the end justify the means and therefore it doesn’t matter how many contract polio from the vaccine? Right now the vaccine is the largest risk of catching polio.

This seems like handwringing for the sake of handwringing because if we stop using the vaccine, polio will return to infect millions. There are interesting ethical debates to be had on vaccination but this is not one of them.

One of the things I dislike about this "dilemma" is playing it off like it's unexpected.

This was true for Smallpox. This will be true for any disease as it approaches eradication if the vaccine isn't 100% side-effect free.

No, this wasn't true for smallpox. The smallpox vaccine didn't use the smallpox virus - it used a related virus which isn't very effective at infecting humans and doesn't seem to have been able to easily mutate into something that was. While smallpox vaccination isn't risk-free and there is the occasional incident of the vaccine virus spreading to family members of US soldiers and causing serious health problems, it can't turn back into smallpox. The fact that the symptoms are so obvious and reliable probably helps here too.

Smallpox has an exceptionally high side effect rate. And that was what I was talking about.

"Adverse Outcome From Vaccine" > "Adverse Outcome from Disease" as a general phenomenon.

Small pox is still available in highly secure laboratories of Both US and Russia. Also, FDA approves small pox vaccine. https://www.fda.gov/news-events/press-announcements/fda-appr...

https://www.cdc.gov/smallpox/vaccine-basics/who-gets-vaccina...

Several articles in the news including the one in Quanta [1,2,3] appear to have caused some misunderstanding. What is clear so far is that “circulating vaccine-derived polioviruses (cVDPVs) can emerge in settings with low population immunity...,” therefore, “all countries must maintain high population immunity.” [4] It was found that “compared with January 2017–June 2018, the number of reported cVDPV outbreaks more than tripled, from nine to 29,” in the most recent survey. [4] As a result, the Global Polio Eradication Initiative” is planning future use of a novel type 2 OPV, stabilized to decrease the likelihood of reversion to neurovirulence.” One of the most significant barriers to polio eradication is “reaching every child – including inconsistent campaign quality, insecurity, conflict, massive mobile populations, and, in some instances, parental refusal to the vaccine.”[5]

It is false to say that somehow cVDPVs had been kept a secret or their importance downplayed. [6] There are critical reasons to remain vigilant of any adverse consequences but keep in mind that every year “hundreds of thousands of cases due to wild polio virus are prevented. Well over 10 million cases have been averted since large-scale administration of OPV began 20 years ago.” [7]

[1] https://www.quantamagazine.org/why-smallpox-is-no-more-but-p...

[2] https://www.nytimes.com/aponline/2019/11/25/health/ap-af-med...

[3] https://www.washingtonpost.com/world/africa/more-polio-cases...

[4] https://www.cdc.gov/mmwr/volumes/68/wr/mm6845a4.htm

[5] http://polioeradication.org/news-post/global-leaders-pledge-...

[6] https://www.ncbi.nlm.nih.gov/books/NBK236293/

[7] https://www.who.int/features/qa/64/en/

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