The warning comes amid a measles outbreak in north London this year which has so far seen over 100 cases.

Chair of the London Assembly Health Committee, Emma Best, said: ‘What we are seeing in London should set alarm bells ringing as vaccination rates are amongst the lowest in the country, and as a result, preventable outbreaks are becoming inevitable rather than exceptional.

‘While the response on the ground has been strong, we cannot keep relying on emergency catch-up campaigns. We need sustained, targeted action to rebuild routine vaccination coverage, improve access in communities and ensure no child falls through the cracks. Without that shift, London will remain exposed to repeated outbreaks that put children's health and lives at risk.'

An extraordinary committee evidence session on the measles outbreak found vaccination rates in London were just 70%, well below the level needed to prevent outbreaks. The majority of cases have been in Enfield this year, where vaccine uptake is just 64%. Around one in five cases has required hospital treatment, with infections largely among unvaccinated children.

The Committee has written to the Mayor of London and the secretary of state for health and social care, urging them to consider how they can support boroughs with low vaccination uptake to deliver sustained, localised vaccination campaigns.

A spokesperson for the London Mayor said: ‘It is hugely concerning that measles cases have risen in London due to low vaccination rates. This is a highly contagious, yet preventable, illness and can be very serious, but the MMRV vaccine is proven to be a safe and effective way to combat this disease. The Mayor has urged Londoners to ensure children and families are up to date with their immunisations, and City Hall continues to support UKHSA, the NHS and local councils to encourage the take-up of vaccines throughout the year to ensure everyone is protected.'

The north London outbreak has so far seen 89 cases in Enfield and 18 cases in Haringey. 

A Haringey Council spokesperson said: ‘We are continuing to work closely with local and national partners to protect residents and limit the spread of measles in Haringey.

‘Vaccination is the most effective way to protect your family and the whole community.  We urge everyone who is not fully vaccinated to act now.'