Faced with a global resurgence of measles, health experts called Tuesday for countries to step up the fight against vaccine resistance, warning the movement was spreading like a contagious disease.
World Health Organization chief Tedros Adhanom Ghebreyesus joined experts and health ministers from a range of countries at an event on "promoting vaccine confidence", amid rising concerns that resistance to immunisation is allowing preventable diseases to flourish.
"No country can afford to be complacent about immunisation," Tedros told the meeting in Geneva, where the WHO is hosting its main annual gathering.
The WHO says cases of measles -- a highly contagious viral infection that can prove fatal -- surged 300 percent in 2018.
Resurgence of the once all-but-eradicated disease is linked to the growing anti-vaccine movement in richer nations, which has been identified as a major global health threat.
"It's a contagious disease," Seth Berkley, who heads the GAVI Vaccine Alliance, told AFP, warning that misinformation about vaccine safety "spreads at the speed of light."
The anti-vax phenomenon has adherents across Western countries but especially in the US, where it has been fuelled by the spread on social media of medically baseless claims, debunked 20 years ago, that the jab could cause autism.
The United States, which sponsored Tuesday's event with the EU and Brazil, lamented the "misinformation" causing vaccination rates in the country to decline.
"Vaccines are some of the most thoroughly tested medical products we have. Vaccines are safe, effective, and lifesaving," US Health and Human Services Secretary Alex Azar told the meeting.
He slammed "social media conspiracy groups (that) confuse well-meaning parents so they hesitate to get the recommended vaccinations."
- 'Real impacts' -
"This misinformation has real impacts," he said, pointing to the more than 700 measles cases in the US so far this year.
Azar dismissed questions about whether past statements by President Donald Trump in support of some anti-vaccination movement claims may bear some responsibility for the problem.
Pointing to recent comments by the president urging Americans to "get your kids vaccinated", he stressed Trump was "extremely firm" in his support of vaccination.
EU Health Commissioner Vytenis Andriukatis meanwhile suggested that vaccine scepticism was in part linked to the fact that vaccines have been so effective that most people have no concept of how devastating the diseases they prevent can be.
"We have become victims of our own success," he said.
Among the measures being taken to inoculate populations against the spread of misinformation about vaccine safety was putting pressure on social media companies like Facebook and Twitter to remove or flag demonstrably false information.
"This is wrong information that is killing people," Berkley said.
According to WHO, vaccines save some three million lives annually.
"Vaccines do not cause autism. Vaccines actually cause adults," said Katherine O'Brien, who heads WHO's immunisation department.