By Danica Kirka Associated Press

LONDON – Britain’s government plans to call a summit of social media companies to discuss what more they can do to fight online misinformation about vaccines following a spike in measles cases.

Although plans for such a gathering were still being worked out, Prime Minister Boris Johnson expressed concern Monday at the rising incidence of measles. He said Britain had a great record in fighting the disease but things were suddenly “going in the wrong direction,” with 230 new measles cases in the first few months of this year.

He said authorities need to address misleading information online about vaccinations.

“I’m afraid people have been listening to that superstitious mumbo jumbo on the internet, all that anti-vax stuff and thinking that the MMR vaccine is a bad idea,” he said while visiting a hospital in southwestern England. “That’s wrong.”

Social media companies have struggled to combat fake news of all sorts, from political propaganda to bogus warnings about vaccines such as MMR for measles, mumps, and rubella.

Pinterest, a leading online repository of vaccine misinformation, took the seemingly drastic step in 2017 of blocking all searches for the term “vaccines.” Facebook, meanwhile, said in March that it would no longer recommend groups and pages that spread hoaxes about vaccines and that it would reject ads that do this.

But anti-vax information still slips through. That includes soundly debunked notions that vaccines cause autism or that mercury preservatives and other substances in them can harm people.

Some experts fear that the online spread of bad information about vaccines is planting or reinforcing fears in parents, contributing to a comeback in recent years of certain dangerous childhood diseases, including measles.

Measles is highly infectious and health officials say at least about 95% of the population must be immunized to prevent outbreaks. In May, Public Health England estimated that about 87% of children aged 5 had gotten both doses.

According to the World Health Organization, there were more reported measles cases worldwide in the first six months of 2019 than in any year since 2006, “with outbreaks straining health care systems and leading to serious illness, disability and deaths.” The U.S. has reported its highest number of measles cases in 25 years.

Some British health officials welcomed Johnson’s proposal but said the country’s health service was already struggling to cope with existing demands. Helen Bedford, a professor at the Institute of Child Health at University College London, noted that numerous doctors’ clinics were closing and the number of health workers in the country had dropped significantly recently.

“This is a system under pressure,” she said in a statement. “We need to put resources into increasing numbers of practice nurses, the skilled work force who day in and day out vaccine children and adults to protect them against serious diseases.”

Johnson set out plans to improve the U.K.’s vaccination rates, calling for health leaders to renew efforts to ensure that 95% of residents have had both doses of the MMR vaccine. The Department for Health will deliver a strategy to address the issue this fall and is expected to consider using technology to identify who may have missed a vaccination and to make booking appointments easier.