Facebook announced their support for public health vaccination efforts which included encouraging people to get a flu vaccine and removing ads with “misinformation that could harm public health efforts”:
Today, we’re launching a new global policy that prohibits ads discouraging people from getting vaccinated. We don’t want these ads on our platform.
Our goal is to help messages about the safety and efficacy of vaccines reach a broad group of people, while prohibiting ads with misinformation that could harm public health efforts. […] Now, if an ad explicitly discourages someone from getting a vaccine, we’ll reject it.
Facebook did however clarify that ads for or against legislation would still be allowed. They’re only interested in restricting discourse on the very thing being legislated:
Ads that advocate for or against legislation or government policies around vaccines – including a COVID-19 vaccine – are still allowed.