The policy change that Facebook made in 2019 during the Brooklyn measles outbreak involved splitting HEALTH MISINFO ab vaccines off from POLITICAL DEBATES about vaccination.

"vaccines cause autism" - no.
"school vax requirements are govt tyranny" - ok https://www.buzzfeednews.com/article/alexkantrowitz/facebook-coronavirus-misinformation-takedowns

I have an insanely long paper on this in the works but: the gist was that this would allow preservation of political debate about vaccination legislation, which has been incredibly heated (CA, NY, NJ within the last year)...

...while stopping the absolutely macabre and wholly made-up "vaccines cause SIDS" insanity by Larry Cook of the group Stop Mandatory Vaccination, who was running GoFundMes and then ads targeting pregnant women with pictures of deceased children. https://www.thedailybeast.com/anti-vaxxer-larry-cook-has-weaponized-facebook-ads-in-war-against-science

Some of the groups, like Cook's, were in violation of the new policies almost immediately. Others, like RFK Jr's misleadingly named "Children's Health Defense" held out a while longer before, it seems, more clearly crossing into pseudoscience nuttery and losing ad privileges.

The decision to elevate the WHO and CDC in this regard I wrote about in The Atlantic recently. If you have nothing else to do on a Sat afternoon, it explains how the measles outbreaks of 2019 informed the policies we're seeing on COVID. https://www.theatlantic.com/ideas/archive/2020/05/health-experts-dont-understand-how-information-moves/611218/

This split is not as clean as it seems, particularly now as the intersection of #Reopen, anti-vax, Q, and other groups is getting even more pronounced as COVID-19 SIP continues. The anti-vax political groups are still, at their core, nearly all true believers in the pseudoscience

And so, if and when a vaccine comes down the pipeline, even if the clinical trials are absolutely spotless, they will have been developing networked activism relationships with other groups for months, and will likely work in concert to oppose it.

This is why, if you saw Plandemic, you saw brief nods to pseudoscience, with a much bigger focus on corruption, conspiracy, and instilling mistrust in health authorities overall. The messaging is largely inseparable now.