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Comment by zozbot234 | Hacker News Reader

There's an injectable vaccine that doesn't contribute to reactivated polio. Also, the oral vaccine doesn't "give" polio to the recipient. The person stays immunized, but then in rare cases may be spreading reactivated polio to third-parties.

So it seems like the injectable vaccine will be strictly preferable if the nOPV strategy fails. It's only disadvantage is that it does not prevent the recipient from spreading polio to others if they become infected, and it looks like that disadvantage may have been illusory anyway.

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No, both the vaccine receipient and third parties are at risk of getting a full-on paralytic polio infection from the oral polio vaccine. When this happens to the recepient it's called vaccine-associated paralytic polio. See for instance https://www.cdc.gov/vaccines/vpd/polio/hcp/vaccine-derived-p...

It's also worth paying attention to the precise distinction between vaccine-derived poliovirus, which is the problem this article was about, and VAPP. VDPD is basically equivalent to normal wild-type poliovirus in terms of its infectivity and effects, but only happens once the vaccine poliovirus has been circulating and mutating for a while and can be protected against via vaccination. VAPP is caused by vaccination and can affect the recipients or those around them, but unlike VDPD the people who suffer from it shouldn't pose any more danger to others than any other vaccine receipient.

> No, both the vaccine receipient and third parties are at risk of getting a full-on paralytic polio infection from the oral polio vaccine.

That seems like it would make the oral vaccine even worse, compared to the injected vaccine. Again, I'm not sure why they think reintroducing traditional type-2 OPV is a good idea if the injected form that won't cause vaccine-derived outbreaks is so easily available. (Of course nOPV is expected to be better than the former OPV, but it's yet to be available.)

Part of the problem is that there wasn't enough supply of the inactivated vaccine, and arguably there still isn't and probably won't be for some time. See for example https://academic.oup.com/jid/article/220/10/1545/5432103 Also, while the inactivated vaccine protects receipients from the risks associated with polio infection, unlike the oral vaccine it may not be all that effective at preventing it from replicating in their bowel and then infecting others.

I'm not exactly sure why the WHO rushed to pull type 2 from the oral vaccine before there was sufficient supply of the inactivated vaccine to replace it, but I get the impression that they didn't expect it would be necessary because they thought that type 2 virus would rapidly disappear once they did so.

That's not the only disadvantage. The injectable vaccine needs a cold chain, and as with all injectables, involves the proper handling and disposal of sharps. It's also physically larger, which is a larger problem than many people realize - vaccination campaigns are actual real world applications of the knapsack problem.

Sure but if it only has to be used in small-scale campaigns to deal with individual flare-ups of the disease, these look like solvable problems. We're not talking about deploying it country-wide.

The responses are not that small-scale, the guidelines call for vaccinating as many children aged 0-5 as can be done with good coverage, e.g. half a million children within 14 days and 1-2 million within 6 weeks.

http://polioeradication.org/wp-content/uploads/2016/07/sop-p...

The injectable does not prevent transmission it 'only' protects the recipient from paralysis they can become infected and be a carrier. Only the oral vaccine prevents the disease spreading.

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