All children aged one to nine in London are to be offered a booster polio vaccine after the UK Health Security Agency declared an ongoing incident.

After initial unusual findings of vaccine-like type-2 poliovirus isolates in London Beckton sewage treatment works in February this year, continuous analysis shows the virus has evolved and that there may be person-to-person transmission in the community.

The UKHSA said it is “urgently investigating” the extent of transmission across north-east and north central London, with poliovirus now having been identified in boroughs including Barnet, Brent, Haringey and Waltham Forest.

With vaccination coverage for the three-dose primary schedules in one-year-olds in London “well below” the UK average and the affected areas being densely populated, the agency warned there is “significant potential” for vaccine-derived poliovirus (VDPV2) to continue spreading.

The Joint Committee on Vaccination and Immunisation (JCVI) has therefore recommended that supplementary polio boosters should be offered to children aged one to nine in the London area, which it said will “help to ensure that there is a high level of protection from paralysis in the area where the VDPV2 is circulating”. 

It said this will help reach unvaccinated children, and may help to reduce onward spread of the virus from those who have already been vaccinated.

“This campaign should start as soon as possible in the London boroughs where VDPV2 has been detected and then be expanded to all London boroughs,” said the committee.

It has been reported that GPs will play a primary role in the booster rollout and will be contacting families as a matter of urgency. Pharmacy Network News has approached the JCVI to learn whether other providers such as pharmacies will also be asked to take part.

The JCVI cited two international cases this year involving paralysis due to polio infection, one affecting an adult male in New York and the other a three-year-old child in Israel. Both were unvaccinated.