Without wastewater sampling, the eradicated virus could have easily spread.

An eradicated form of wild polio surfaced in routine wastewater monitoring in the Netherlands last year, offering a cautionary tale on the importance of monitoring for the tenacious virus, researchers report this week in the journal Eurosurveilance.

The sewage sample came up positive for infectious poliovirus in mid-November and genome sequencing revealed a strain of wild poliovirus type 3, which was declared globally eradicated in 2019. Its potential revival would be a devastating setback in the decades-long effort to stamp out highly infectious and potentially paralytic germ for good. //

For brief background, there are three types of wild polioviruses: type 2 and type 3 have been eradicated, with the former being knocked out in 2015. Wild poliovirus type 1 continues to circulate in Afghanistan and Pakistan. There are also occasional vaccine-derived polioviruses that circulate in communities with low vaccination rates, which recently occurred in New York.

The positive wastewater sample last year was the first and only indication of a polio infection with the bygone strain in the Netherlands. It occurred in an employee of a vaccine production facility run by Bilthoven Biologicals, which makes inactivated polio vaccines. The Netherlands had set up routine wastewater surveillance around the production site to monitor for such a viral escape. //

reviewer1 Smack-Fu Master, in training
3y
40
As a brief supplementary primer on poliovirus vaccines, there are two major versions, Salk's inactivated polio vaccine and Sabin's oral polio vaccine. Both of them are incredibly good at protecting against the paralytic disease of poliomyelitis. They are both less than 100% effective at preventing infection and replication of the virus in a vaccinated person's intestinal tract. So they protect the vaccinated person but should not be counted on to build towards herd immunity because they don't prevent someone from getting infected, making a few million new copies of the virus and putting those back into the water supply (or whatever else they touch without washing their hands properly). For more, see: https://www.who.int/teams/health-pr...specifications/vaccines-quality/poliomyelitis

The oral polio vaccine is better at producing a mucosal immune response in the intestines, so it's better at preventing someone from getting meaningfully infected at all. However, the oral polio vaccine uses live attenuated virus. The tricky thing about live virus is that it mutates and, given enough time, those mutations can undo the attenuation mutations and allow it to become more virulent.

So each vaccine has strengths and weaknesses. At this point, I think the most important thing to know is that being vaccinated for poliovirus protects against getting sick, not against getting infected, and infected people can and do shed virus that can infect others. //

FreeRangeOrganicSoyLatteCappuccino Ars Praetorian
2y
2,629
Uncivil Servant said:
Just to be clear, the inactivated vaccine still protects against infection as well as paralytic polio, but the oral attenuated vaccine provides better protection against the initial infection compared to the inactivated vaccine.

There's an important distinction between "the inactivated vaccine is less effective in preventing (non-paralytic) infection compared to the oral attentuated vaccine" and "the inactivated vaccine does not prevent (non-paralytic) infections".

The oral vaccine also has some advantages in terms of storage and transporation in rural areas of developing nations. It's also a lot easier to administer, especially to young children. But yes, it comes with risks. Hopefully soon polio will go the way of smallpox and rinderpest.
Click to expand...The inactivated vaccine (iPV) provides minimal protection against intestinal mucosal infection. So a person vaccinated with iPV is immune from paralytic complications of polio, can still be infected with polio and continuously poop out viral particles. iPV protects the person, not the population.

The oral vaccine (OPV) provides protection against BOTH intestinal mucosal infection and the paralytic complications of polio. However, there is a chance that the OPV mutates and reverts back to an active virus.

Presumably, this vaccine factory worker was working with a lab sample of type 3 polio and got sloppy with technique. That some worker was presumably vaccinated using the iPV which protected them from paralytic polio, but did NOT protect them from getting polio into their gut and replicating/shedding virus.

CKing123 Wise, Aged Ars Veteran
7y
192
mgforbes said:
Does getting both the injected and oral version of the vaccine confer better immunity, or is it a case of when you've had one, the other one doesn't work?
So OPV (Oral Polio Vaccine) provides antibodies in the guts which means you can blunt transmission and provides protection against infection for a few months. IPV (Inactivated Polio Vaccine) only creates antibodies in blood so you can still get infected and shed the virus (you can for OPV after a while too, but you will blunt transmission). However, the antibodies in blood prevent polio from getting to nerves and causing paralysis. However, if you ever have had OPV, you can be given IPV later and it will increase antibodies in the guts once again without requiring you to take OPV again.