Though it's a bit too late for inoculation, Facebook is taking steps to limit the damage being done by anti-vaxxers on its platforms.
The social network has announced:
- it'll no longer allow ads "that include misinformation about vaccinations'
- advertisers will no longer be able to target adverts at people interested in topics like 'vaccine controversies'
- pages and groups that spread lies and hoaxes about vaccines won't show up in searches or recommendations
- anti-vaxxer content will no longer show up on Instagram's Explore section or its hashtag pages.
"We are fully committed to the safety of our community and will continue to expand on this work," Facebook vice-president of global policy management Monika Bickert said.
"Leading global health organisations, such as the World Health Organization and the US Centers for Disease Control and Prevention, have publicly identified verifiable vaccine hoaxes. If these vaccine hoaxes appear on Facebook, we will take action against them.
"For example, if a group or page admin posts this vaccine misinformation, we will exclude the entire group or page from recommendations, reduce these groups and pages' distribution in News Feed and search, and reject ads with this misinformation."
Despite vaccines' success in eradicating some serious diseases and severely limiting others, there has in recent years been growing opposition. The movement can be traced back to a fraudulent 1998 paper which linked the MMR vaccine for measles, mumps and rubella to autism, and the advent of social media has seen it spread - much like a virus itself.
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Thousands of New Zealanders belong to anti-vaccination Facebook groups, with names like 'NZ Natural Immunity', 'Anti-Vaccination Pregnancy Support Group' and 'WAVES - Warnings About Vaccine Expectations'.
Facebook says it'll be trying harder to point people towards more reliable sources of information.
"We are exploring ways to give people more accurate information from expert organisations about vaccines at the top of results for related searches, on pages discussing the topic, and on invitations to join groups about the topic," said Ms Bickert. "We will have an update on this soon."
Vaccines work by teaching the body's immune system to recognise diseases before they're caught. This way the body can fight back immediately as soon as the disease is contracted.
Some people have to avoid vaccinations for genuine reasons - they might be too young or old, have a compromised immune systems, be HIV-positive or undergoing chemotherapy, for example. These people are protected by the concept of herd immunity - if everyone else is vaccinated, diseases will have a difficult time spreading.
An outbreak of chicken pox at a school in the US last year was blamed on a lack of herd immunity, with more than 70 percent of its students being exempted from receiving vaccines by their parents.
The World Health Organization recently named anti-vaxxers, as opponents are known, as one of the top 10 threats to health worldwide.