“After a period of progress where we were once able to declare Britain measles free, we’ve now seen hundreds of cases of measles in the UK this year. One case of this horrible disease is too many, and I am determined to step up our efforts to tackle its spread,” Prime Minister Boris Johnson said in a statement on Sunday.

Johnson added that that he would summon social media companies “to discuss how they can play their part in promoting accurate information about vaccination.”

{mosads}Measles, a highly infectious disease which is almost entirely preventable with two doses of vaccine, was declared eliminated in the country three years ago. But it seems to be making a comeback.

There have been close to 90,000 cases of measles reported in Europe for the first six months of 2019, exceeding the total for 2018.

The United States has reported its highest number of cases in 25 years.

That comeback has increased scrutiny on the role social media plays in circulating anti-vaccine misinformation. 

Several companies have taken steps to move such posts out of their suggested content.