The anti-vaccine movement is nearly as old as vaccines themselves. For as long as humans have sought to harness our immune system’s incredible ability to recognize and fight infectious invaders, critics and conspiracy theorists have opposed these efforts. 

Anti-vaccine tactics have advanced since the early days of protesting “unnatural” smallpox inoculation, and the rampant abuse of scientific data may be the most effective strategy yet. 

Here’s how vaccine opponents misuse data to deceive people, plus how you can avoid being manipulated.

Misappropriating raw and unverified safety data

Perhaps the oldest and most well-established anti-vaccine tactic is the abuse of data from the federal Vaccine Adverse Event Reporting System, or VAERS. The Centers for Disease Control and Prevention and the Food and Drug Administration maintain VAERS as a tool for researchers to detect early warning signs of potential vaccine side effects. 

Anyone can submit a VAERS report about any symptom experienced at any point after vaccination. That does not mean that these symptoms are vaccine side effects.

VAERS was not designed to determine if a specific vaccine caused a specific adverse event. But for decades, vaccine opponents have misinterpreted, misrepresented, and manipulated VAERS data to convince people that vaccines are dangerous. 

Anyone relying on VAERS to draw conclusions about vaccine safety is probably trying to trick you. It isn’t possible to determine from VAERS data alone if a vaccine caused a specific health condition.

VAERS isn’t the only federal data that vaccine opponents abuse. Originally created for COVID-19 vaccines, V-safe is a vaccine safety monitoring system that allows users to report—via text message surveys—how they feel and any health issues they experience up to a year after vaccination. Anti-vaccine groups have misrepresented data in the system, which tracks all health experiences, whether or not they are vaccine-related.

The U.S. Department of Defense’s Defense Medical Epidemiology Database (DMED) has also become a target of anti-vaccine misinformation. Vaccine opponents have falsely claimed that DMED data reveals massive spikes in strokes, heart attacks, HIV, cancer, and blood clots among military service members since the COVID-19 vaccine rollout. The spike was due to an updated policy that corrected underreporting in the previous years

Misrepresenting legitimate studies

A common tactic vaccine opponents use is misrepresenting data from legitimate sources such as national health databases and peer-reviewed studies. For example, COVID-19 vaccines have repeatedly been blamed for rising cancer and heart attack rates, based on data that predates the pandemic by decades. 

A prime example of this strategy is a preliminary FDA study that detected a slight increase in stroke risk in older adults after a high-dose flu vaccine alone or in combination with the bivalent COVID-19 vaccine. The study found no “increased risk of stroke following administration of the COVID-19 bivalent vaccines.”

Yet vaccine opponents used the study to falsely claim that COVID-19 vaccines were uniquely harmful, despite the data indicating that the increased risk was almost certainly driven by the high-dose flu vaccine. The final peer-reviewed study confirmed that there was no elevated stroke risk following COVID-19 vaccination. But the false narrative that COVID-19 vaccines cause strokes persists.

Similarly, the largest COVID-19 vaccine safety study to date confirmed the extreme rarity of a few previously identified risks. For weeks, vaccine opponents overstated these rare risks and falsely claimed that the study proves that COVID-19 vaccines are unsafe. 

Citing preprint and retracted studies

When a study has been retracted, it is no longer considered a credible source. A study’s retraction doesn’t deter vaccine opponents from promoting it—it may even be an incentive because retracted papers can be held up as examples of the medical establishment censoring so-called “truthtellers.” For example, anti-vaccine groups still herald Andrew Wakefield nearly 15 years after his study falsely linking the measles, mumps, and rubella (MMR) vaccine to autism was retracted for data fraud. 

The COVID-19 pandemic brought the lasting impact of retracted studies into sharp focus. The rush to understand a novel disease that was infecting millions brought a wave of scientific publications, some more legitimate than others. 

Over time, the weaker studies were reassessed and retracted, but their damage lingers. A 2023 study found that retracted and withdrawn COVID-19 studies were cited significantly more frequently than valid published COVID-19 studies in the same journals. 

In one example, a widely cited abstract that found that ivermectin—an antiparasitic drug proven to not treat COVID-19—dramatically reduced mortality in COVID-19 patients exemplifies this phenomenon. The abstract, which was never peer reviewed, was retracted at the request of its authors, who felt the study’s evidence was weak and was being misrepresented. 

Despite this, the study—along with the many other retracted ivermectin studies—remains a touchstone for proponents of the drug that has shown no effectiveness against COVID-19.

In a more recent example, a group of COVID-19 vaccine opponents uploaded a paper to The Lancet’s preprint server, a repository for papers that have not yet been peer reviewed or published by the prestigious journal. The paper claimed to have analyzed 325 deaths after COVID-19 vaccination, finding COVID-19 vaccines were linked to 74 percent of the deaths. 

The paper was promptly removed because its conclusions were unsupported, leading vaccine opponents to cry censorship. 

Applying animal research to humans

Animals are vital to medical research, allowing scientists to better understand diseases that affect humans and develop and screen potential treatments before they are tested in humans. Animal research is a starting point that should never be generalized to humans, but vaccine opponents do just that.

Several animal studies are frequently cited to support the claim that mRNA COVID-19 vaccines are dangerous during pregnancy. These studies found that pregnant rats had adverse reactions to the COVID-19 vaccines. The results are unsurprising given that they were injected with doses equal to or many times larger than the dose given to humans rather than a dose that is proportional to the animal’s size. 

Similarly, a German study on rat heart cells found abnormalities after exposure to mRNA COVID-19 vaccines. Vaccine opponents falsely insinuated that this study proves COVID-19 vaccines cause heart damage in humans and was so universally misrepresented that the study’s author felt compelled to dispute the claims. 

The author noted that the study used vaccine doses significantly higher than those administered to humans and was conducted in cultured rat cells, a dramatically different environment than a functioning human heart. 

How to avoid being misled

The internet has empowered vaccine opponents to spread false information with an efficiency and expediency that was previously impossible. Anti-vaccine narratives have advanced rapidly due to the rampant exploitation of valid sources and the promotion of unvetted, non-credible sources. 

You can avoid being tricked by using multiple trusted sources to verify claims that you encounter online. Some examples of credible sources are reputable public health entities like the CDC and World Health Organization, personal health care providers, and peer-reviewed research from experts in fields relevant to COVID-19 and the pandemic. 

Read more about anti-vaccine tactics:

• How vaccine opponents spread misinformation
• How misinformation tricks our brains
• How vaccine opponents use kids to spread misinformation 

This article first appeared on Public Good News and is republished here under a Creative Commons license.