An 18-month-old child in Berlin who had not been vaccinated against measles has died of the virus, German health officials announced Monday. The city has seen more than 600 cases since a measles outbreak began in October. Vaccination is not mandated in Germany, but the toddler’s death has raised public-health fears in the country. “We take the current situation very seriously,” said a spokeswoman for the German health ministry, adding that the country will be trying to increase vaccination rates. “If that doesn’t help, then we will have to discuss other measures.” The news comes as U.S. health officials announced Monday that the country has had 154 measles cases thus far in 2015. In 2000, the U.S. declared measles to be eliminated thanks to years of vaccination efforts.