Online spies have infiltrated anti-vaccine Facebook groups and found group members issuing calls to attack vaccine advocates, including mothers who are mourning their dead children.
The result is waves of harassment, with dozens of comments or more coming in all at once, according to victims.
"I call these cybermobs. It's death by a thousand cuts. It's like a thousand bee stings," Citron said.
Citron said Facebook should come up with a way to report the mob instead of having to report each individual piece of content.
"Facebook needs to view the cybermob as a real phenomenon," she said. "There should be a way where users can let them know this storm is happening -- where they can say, 'See my page, a cybermob has descended.' ""