The UK has lost its measles elimination status, the World Health Organization has announced.
The move was based on the spread of cases in 2024 when there were 3,600 suspected cases.
Elimination status means there is no sustained transmission so this decision was largely expected, given the scale of the outbreaks in 2024.
There were more than 1,000 cases last year as well. The move is also a reflection of the fact vaccination rates are below the 95% threshold required to achieve herd immunity – when enough people in a community are vaccinated against a disease, making it hard for the pathogen to spread.
The UK was first declared measles-free in 2017, but lost the status two years later, before regaining it after spread of the virus was almost halted completely in 2021 – although that was mainly because social distancing during the pandemic.
Outbreaks in late 2023 meant measles started spreading more quickly again, leading to the surge in cases in 2024.
Vaccination uptake at the end of 2024 was 92% for the first dose and just below 85% for the second dose.
Dr Vanessa Saliba, consultant epidemiologist at UKHSA, said: “Infections can return quickly when childhood vaccine uptake falls – measles elimination is only possible if all eligible children receive two MMRV doses before school.
“The NHS is making vaccination easier, including offering the second MMRV dose earlier at a new 18-month appointment to boost uptake and support elimination goals.”
She said older children and adults could still get vaccinated as the NHS offered catch-up jabs.
Dr Bharat Pankhania, from the University of Exeter, said: “Measles is an infection that can be prevented by vaccine – and it’s extremely concerning that in the UK we now have pockets of low or no vaccine uptake.
“We urgently need to remedy this situation.”
Pankhania said that needed to include easier access to GPs, more health visitors who can immunise babies in their homes and countering wrong information about vaccine safety.