Britain's Prime Minister Boris Johnson on Monday ordered urgent action to boost the number of young people being vaccinated against life-threatening diseases including measles.
The UK achieved measles-free status in 2016 but lost it this year as the number of reported cases grew over more than 12 months in 2017 and 2018.
According to government figures, there were 991 cases in 2018 and 231 during the first quarter of this year.
Two jabs are required to be immunised from the disease. Coverage of the first dose in the UK has reached the 95% target from the World Health organisation but the coverage for the second dose has slipped to 87.4%.
To remedy that decline, the Prime Minister has called on doctors to promote 'catch up' vaccinations for children or young adults who may have missed out on the second dose.
The National Health Service has been asked to update its online advice to address "misleading information about the danger of vaccines" while a summit will be organised with social media companies to discuss "how they can play their part in promoting accurate information about vaccination."
The Department for Health and Social Care will also deliver a "comprehensive strategy" to tackle the increase in measles cases in the Autumn.
"This is a global challenge and there's a number of reasons why people don't get themselves or their children the vaccines they need, but we need decisive action across our health service and society to make sure communities are properly immunised," Johnson said in a statement.
The head of immunisation at Public Health England, Dr Mary Ramsay, added: "Losing our 'measles-free' status is a stark reminder of how important it is that every eligible person gets vaccinated."
"Measles is one of the most infectious diseases known to man — only one person travelling back to an area with lower vaccination rates can lead to an outbreak. Anyone who has not received two doses of MMR (Measles, Mumps, Rubella) vaccine is always at risk," she explained.
More than 13,000 measles cases were reported across the European Union from July 2018 to June 2019 — 10,129 were lab-confirmed — according to the European Centre for Disease Prevention and Control (ECDC).
France reported the highest number (2,367), followed by Italy (1,831) and Romania (1,628). The UK, meanwhile, reported 699 cases.