10 Aug 2022
All children aged one to nine in London should receive a polio vaccination in the coming weeks, public health experts have said as a new booster programme is announced.
The UK Health Security Agency said that, since early February, 116 polioviruses had been identified in 19 sewage samples from boroughs in north-east and central London including Barnet, Camden, Hackney, Haringey, Islington and Waltham Forest.
Experts say it is unclear how many people may have been infected but that, to date, no cases of polio – or related paralysis – have been reported...
The newly announced booster programme for children aged one to nine, recommended by the Joint Committee on Vaccination and Immunisation (JCVI), is set to run alongside a previously announced polio vaccine catchup campaign, and will begin in boroughs of London where poliovirus has been detected and vaccination rates are low...
Saliba added that while polio was a serious infection that could cause paralysis, as a result of vaccinations the last case in the UK was in 1984...
While a small number of polioviruses are detected in sewage in the UK each year, the large number detected over recent months is unusual, and appears to reflect transmission of the virus in the community.
Public health experts said it appeared such transmission was asymptomatic, and
was likely to have been caused by an individual recently vaccinated with live oral polio vaccine (OPV) entering the UK. OPV generates excellent gut immunity against polio; however, people who have been recently vaccinated can shed vaccine-like virus in their faeces.
While this weakened form of the virus does not cause illness, the concern is that if it circulates it can gain mutations that increase its virulence, resulting in vaccine-derived poliovirus – which has the potential, albeit rare, to cause paralysis in those who are unvaccinated.
The UKHSA said that while most of the isolates from London sewage had so far involved vaccine-like poliovirus, some contain vaccine-derived poliovirus.
The UK switched from using OPV to an inactivated poliovirus vaccine (IPV) in 2004. While IPV is very effective in preventing polio disease, it does not produce as good gut immunity as OPV, meaning it is possible fully vaccinated individuals could have an asymptomatic infection.