Measles cases have increased by 400% across Europe between 2016 and 2017, according to statistics from the World Health Organization (WHO).
A total of 21,315 cases of measles and 35 lives lost were reported in 2017.
The WHO says there have been declines in overall routine immunisation coverage, as well as consistently low coverage among some marginalised groups and interruptions in vaccine supply or underperforming disease surveillance systems.
Dr Zsuzsanna Jakab, WHO regional director for Europe, described it as "a tragedy we can not accept".
Japan's Foreign Ministry is calling on people to consider getting vaccinated if they plan to visit European countries with a growing number of measles cases.
Measles symptoms include a runny nose, sneezing and cough, sore, red eyes, a high temperature and, after a few days, a red-brown blotchy rash. Measles cases were highest in Romania, Italy and Ukraine.
Last September, it was announced that measles had been officially eradicated in the United Kingdom - meaning it had not freely circulated for three years - thanks to widespread immunisation with the MMR vaccine.
The WHO said 15 countries, including Greece, Germany, and Serbia, confirmed more than 100 patients. The "anti-vax" movement has claimed that vaccinations typically given to newborns and young children may cause serious side-effects; most notably was the development of autism.
"Every new person affected by measles in Europe reminds us that unvaccinated children and adults, regardless of where they live, remain at risk of catching the disease and spreading it to others who may not be able to get vaccinated", Dr Jakab said.
Around 95% of cases of measles happen in low-income countries, and globally the fatality rate of measles is one in five.
Most deaths from measles result from severe complications such as diarrhoea, dehydration, brain inflammation or respiratory infections, according to Medicins Sans Frontiers.
"This short-term setback can not deter us from our commitment to be the generation that frees our children from these diseases once and for all".