The system is designed to provide early warning of what might or might not be actual side effects. But anti-vaccine groups are bending the data to their own ends.
The company said ads and other content containing false information about vaccines will be pulled from the platform and accounts that persist in disseminating discredited opinions will be disabled.
Families learn to be skeptical about vaccines in communities where incomplete vaccination is the norm. A researcher into the phenomenon found that people are ready to listen, if they're heard, too.
So far this year, 55 measles cases have been confirmed in Washington state, most of them in unvaccinated children. The outbreak's epicenter is Clark County, Wash., just north of Portland, Ore.
As of Monday, public health authorities reported 36 cases, most affecting children under the age of 10. All but four of those with the highly contagious disease have not been vaccinated.
The HPV vaccine prevents cancer, but in a survey most parents said they don't want it to be required for school. They're much happier with a mandate if they're given an opportunity to opt out.
State health officials suspect California's big measles outbreak last year helped persuade parents to get their kids immunized against other illnesses, too.
Prime Minister Tony Abbott says that starting in 2016, welfare payments and childcare rebates will be cut off to families that take a "conscientious objector" exemption to avoid immunizations.
