“Reject the Experimental Vaccine”: How Anti-Vaccine Narratives Can Defy Partisan Boundaries

“Reject the Experimental Vaccine”: How Anti-Vaccine Narratives Can Defy Partisan Boundaries

  • July 6, 2021

By Jacob Silver

Quick—picture an anti-vaxxer. Who do you see? A middle-aged Trump supporter? A young Black Lives Matter protester? Ten lines of Python code? Whoever popped into your mind, you almost certainly weren’t wrong.

Back in March, we wrote about a proliferation of anti-vaccine narratives on Instagram following Facebook’s stated commitment to crack down on accounts spreading anti-vaccine disinformation as a public health imperative. Since then, major anti-vax figures and groups have been banned from social media platforms, which have periodically updated their policies. But anti-vaccine narratives have persisted, and plenty have grown in popularity. We dove into one such narrative that has proven popular and exists in a rhetorical gray area; an area into which platform moderation teams are unable or unwilling to go. Our findings suggest that while disinformation often coincides with deeply polarizing political views, promoters of vaccine skepticism may be employing a more politically inclusive approach.

The “Experimental Vaccine”

Nearly half a year into the COVID-19 vaccine rollout, one misleading narrative has withstood the tests of both time and platform moderation: that the vaccines are “experimental” and therefore not to be trusted. These claims are false in both spirit and semantics, since by definition, “experimental vaccines” have not yet completed clinical trials. However, the Pfizer, Moderna, Johnson & Johnson, AstraZeneca, Sinopharm, and Sinovac vaccines have been shown to be safe and effective through rigorous testing, thereby earning emergency-use authorization from the WHO and associated regulatory bodies.

Still, the narrative has proven sticky, largely due to its intersection with the top concerns cited by those who don’t intend to get the vaccine: that the vaccines were developed “too quickly” and that they rely on “new technology” that is not yet fully understood.

No popular narrative sticks without evangelists, and this one is no exception. To get a sense of who they were, we pulled every tweet mentioning the phrase “experimental vaccine” from January to May and analysed the content of the messages and the profiles of their spreaders.  

Are the accounts coordinating and/or inauthentic?

While the purpose of this particular analysis was not to detect coordinated inauthentic behavior (CIB), it is a question worth asking for any situation in which disinformation is being spread online. Though a 2020 study found anti-vaccine bot networks may have limited reach on Twitter, the vaccine rollout since then has transformed the COVID-19 discourse dramatically.

We observed several signals to suggest coordination may be occurring in this case. For example, nearly a quarter of accounts in the dataset were created just in the past year. The distribution of account creation dates therefore appears suspicious, though it is worth noting that Twitter saw a surge of new users in 2020 as the pandemic forced most social interaction into online spaces.

But we also observed few obvious signs of coordination or inauthenticity in the content. For example, we did not see any identical copy-and-paste messages from distinct accounts, though there were a number of users directing the same messages at a number of accounts in relatively quick succession. We assume there is coordination occurring—maybe even a lot—and additional in-depth network and linguistic analyses may prove that out. But our sense is that the “experimental vaccine” narrative is compelling enough at this stage not to require coordination to popularize it.

The question of coordinated accounts is incredibly important to answer from a policy and enforcement perspective. But whether or not large numbers of these accounts are fake or moderated, we can learn a great deal from how they choose to present themselves.

Ideological Diversity

As shown above, it’s possible that some number of the accounts pushing “experimental vaccine” tweets are inauthentic. But whatever the case may be, there is ideological diversity in the accounts spreading the narrative, which heightens its potential to reach a broad swath of people.

To understand partisan affiliations among users in the Twitter dataset, we extracted all the hashtags from users’ bios and ranked them by popularity. I then manually labeled those top hashtags for clear political alignments to the right (ie. #maga) or left (ie. #blm), skipping those that were vague (ie. #politics) or unrelated to the left-right polarity (#bitcoin) in American, British or Canadian politics. I assessed a sample of accounts to ensure that the appearance of these popular hashtags indeed signaled consistent advocacy for either conservative or left-liberal policies. I also scanned tweet content to validate that the vast majority of comments were supporting rather than mocking the idea that the “experimental vaccine” is unsafe. The result is a mapping out of highly political accounts engaged in this conversation.

Ten percent of the accounts in the labeled data presented as leftwing or liberal. Perhaps what stands out to you in the graphic above is the sea of red bubbles, which indeed dominate the conversation. However, vaccine disinformation narratives tend to be far more partisan; in conducting the same analysis for the phrase “masks don’t work,” we did not find a single tweet out of over 800 that came from a self-identified liberal. Echo chambers amplifying disinformation within their own set are very troubling; narratives that find resonance beyond the walls of those echo chambers are troubling in a different way.


Our research supports several well-established narratives around vaccine hesitancy: that conservatives over-index among COVID-19 vaccine skeptics, and that armies of online accounts both fraudulent and authentic seek to foster that skepticism with carefully chosen talking points. But it also exposes an ideological diversity among those accounts that may defy common assumptions around anti-vaccine sentiment in 2021. In this next phase of the battle against anti-vaccine disinformation, researchers and health authorities must work to understand and address these nuanced narratives as they arise. Meanwhile, platform moderation teams must chart the evolution of these narratives lest they be continually outpaced by often subtle variations on the same misleading content.

Some anti-vaccine narratives piggy-back off of strong partisan associations. The same right-wing sentiments that motivated anti-mask protests in 2020 have carried over into the vaccine rollout, while liberal sensibilities around health and wellness have deep roots in the anti-vaccine movements of the past several decades. But the “experimental vaccine” talking point is one of many that carries no such political baggage—and that may make it easier to travel. 

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