A vaccine-derived version of poliovirus has repeatedly surfaced in London sewage over the past several months, suggesting there may be a cryptic or hidden spread among some unvaccinated people, UK health officials announced Wednesday.
No polio cases have been reported so far, nor any identified cases of paralysis. But sewage sampling in one London treatment plant has repeatedly detected closely related vaccine-derived polioviruses between February and May.
This suggests
>it is likely there has been some spread between closely-linked individuals in North and East London and that they are now shedding the type 2 poliovirus strain in their feces,
the UK Health Security Agency (UKHSA) said.
This is not a new phenomenon, out of the 365 polio cases of 2019, all but 22 were cause by circulating vaccine-derived poliovirus (cVDPV). Due to that and the very low incidence of actual wild-type polio cases, most industrialized countries switched to inactivated vaccines which do not have the ability to replicate and/or circulate. they’re less effective though.
This not necessarily something extraordinary. I remember similar news here in Finland. In the City of Tampere, polio has been found in sewage since 2008 despite no outbreak ([Yle](https://yle.fi/uutiset/3-6912548) in Finnish). I also found news articles about Israeli sewers having a lot of poliovirus from 2013.
It was speculated that there could a symptomless carrier of poliovirus who may have got the virus even decades ago.
But of course there may be unvaccinated people who come from or visit Niger, Pakistan or Afghanistan where polio can still be found.
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A vaccine-derived version of poliovirus has repeatedly surfaced in London sewage over the past several months, suggesting there may be a cryptic or hidden spread among some unvaccinated people, UK health officials announced Wednesday.
No polio cases have been reported so far, nor any identified cases of paralysis. But sewage sampling in one London treatment plant has repeatedly detected closely related vaccine-derived polioviruses between February and May.
This suggests
>it is likely there has been some spread between closely-linked individuals in North and East London and that they are now shedding the type 2 poliovirus strain in their feces,
the UK Health Security Agency (UKHSA) said.
This is not a new phenomenon, out of the 365 polio cases of 2019, all but 22 were cause by circulating vaccine-derived poliovirus (cVDPV). Due to that and the very low incidence of actual wild-type polio cases, most industrialized countries switched to inactivated vaccines which do not have the ability to replicate and/or circulate. they’re less effective though.
This not necessarily something extraordinary. I remember similar news here in Finland. In the City of Tampere, polio has been found in sewage since 2008 despite no outbreak ([Yle](https://yle.fi/uutiset/3-6912548) in Finnish). I also found news articles about Israeli sewers having a lot of poliovirus from 2013.
It was speculated that there could a symptomless carrier of poliovirus who may have got the virus even decades ago.
But of course there may be unvaccinated people who come from or visit Niger, Pakistan or Afghanistan where polio can still be found.