Though polio was declared eradicated in most countries over two decades ago, a vaccine-derived strain has been detected multiple times this year in a London neighborhood's sewage system. UK health authorities and the WHO are closely monitoring the situation.
Poliomyelitis, or polio, is a highly infectious viral disease that primarily affects children under 5. Eradicated in most countries by 1999 and in Africa by 2020, it has resurfaced in headlines following a UK Health Security Agency (UKHSA) press release on June 22, 2022. Authorities confirmed the detection and isolation of a type 2 poliovirus in a Beckton sewage treatment plant in London.
This is not a wild poliovirus strain, which have been nearly eliminated worldwide through effective global vaccination campaigns. Only wild type 1 (PV1) circulates in Afghanistan and Pakistan. The London strain is a vaccine-derived poliovirus (VDPV), specifically type 2 (VDPV2), originating from the oral polio vaccine.
Such findings are not entirely new; UK authorities typically identify one to three VDPVs annually via routine surveillance, often linked to travelers vaccinated abroad. These are usually isolated incidents. However, this case stands out: detections occurred twice in 2022—in February and May—both in Beckton. The WHO, informed by the UKHSA, notes a phylogenetic link between the strains.
This pattern raises concerns about potential person-to-person transmission. So far, only environmental samples have been found—no human cases, paralytic symptoms, or related clinical reports. With high vaccination rates in the UK and globally, the risk of an outbreak remains low. Still, the UKHSA urges London residents to ensure children's vaccinations are current.
