Why health misinformation outruns the facts
Health misinformation spreads through emotional appeals, gaps in scientific understanding, social networks and organised campaigns. Confident falsehoods compete with explanations that carry uncertainty and qualifications.
False beliefs and scientific understanding
Misinformation is incorrect information that may be shared accidentally; disinformation is intentionally false information, although research has not always drawn clear boundaries between these terms, rumour and fake news. Being misinformed means believing something counterfactual, whereas being uninformed means not knowing; the two can coexist in one person. Incorrect scientific beliefs have practical consequences, especially when people are vocal and politically active, and beliefs depend heavily on where information comes from.
Civic science literacy is the ability to find scientific information, understand it and use it in decisions about matters such as vaccination, voting and food. A 2023 account put American civic science literacy at 28%, while more than half of people were interested in science: an audience wanting information without the skills to interpret it.
Five causes contribute to this gap.
- Gaps in fundamental scientific knowledge, such as the misconception that food can be free of chemicals.
- Susceptibility to logical fallacies, including the appeal to nature: treating something natural as inherently better than something synthetic.
- Overconfidence: people strongly opposed to genetically modified organisms may know little about them while rating their knowledge highly, resist further learning and pull policy away from scientific evidence.
- Misunderstanding research design, such as treating a small study with uncontrolled confounders as decisive or assuming findings in cells or rats apply to people.
- Misunderstanding scientific discovery: categorical claims omit dose, exposure and species, while scientists qualify conclusions and expect knowledge to develop.
Changing advice can reflect additional knowledge rather than an earlier conclusion having been wrong. Anecdotes presented as evidence, false authorities, fear of chemicals with unfamiliar names, false balance between established evidence and unsupported claims, oversimplified clickbait and confusion between correlation and causation are further routes for misinformation. Chemical names follow systematic rules based on structure; an unpronounceable name does not itself establish danger.
Emotion, confidence and trust
Good research can be hidden behind paywalls and technical language, leaving audiences exposed to poor science reporting in headlines. People may make decisions primarily on emotion and use logic to justify them afterwards. Influencers and celebrities can spread misinformation supported by biased or misappropriated research, undermining the credibility of public-facing content.
Research published in 2018 found false news travelled farther and faster online and persisted longer than truthful information. One explanation is that truthful medical and scientific communication must convey uncertainty, caveats and the possibility of changing answers, whereas a liar can offer a satisfying account without those qualifications.
Failures in care can also create an opening for alternatives: long waits for specialist appointments and hurried encounters can leave people with chronic illness or pain feeling unheard and distrustful of the medical establishment. Misinformation can widen the gap between perceived and actual risk, cause health anxiety, discourage preventive care and vaccination, increase spending on ineffective remedies and turn people against scientific and regulatory expertise. Its harms extend from individuals to communities.
Networks and attention
Social media can form insular bubbles and echo chambers that reinforce misinformation without exposure to different views. Rumours also circulate through families and communities, where their influence can be stronger still. A 2019 account described viral misinformation as digitally enabled emotional contagion and reported that it had been called the biggest pandemic risk of the time.
Hypertext links pieces of information into paths chosen by the reader rather than a single route set by the author. A 2021 critique argues that this can fragment scientific content and blur its boundary with comments and personal opinions: following more links may feel like deeper understanding while remaining superficial. This critique likens viral circulation to repeated copying in which words and phrases may be added or lost, changing the message and helping generate apparent scientific news that is false.
Clickbait uses a title to arouse enough curiosity to make a reader open a link, including in communication between scientists. Curiosity can arise from a perceived knowledge gap and is strongest at moderate confidence in an answer, rather than complete ignorance or perceived complete knowledge. Priming information, moderate knowledge and curiosity underpin the technique. A suggestive title may attract attention through a fashionable subject without addressing the relevant question.
The 2021 critique argues that commercially attractive studies with weak data may be published and disseminated quickly, while substantial but less attention-grabbing work struggles to reach an audience. It also warns that unsupported denials of established findings attract curiosity and profit, and that treating the midpoint between supported and unsupported positions as the truth shifts conclusions away from the evidence.
Organised campaigns
Vaccine misinformation includes organised, well-funded campaigns rather than only isolated mistaken posts. A 2019 account described groups in the United States and Europe using more than 400 websites, alongside social media, to spread fear and conspiracy theories. A 2018 study found bots and Russian trolls posting both pro-vaccination and anti-vaccination messages framed to provoke antagonism between the two sides.
Peter Hotez's 2022 account distinguishes three stages in the development of organised antivaccine activism.
- A vaccine–autism campaign beginning with the 1998 claims about MMR, followed by shifting allegations about thiomersal, schedules and aluminium despite studies finding no vaccine–autism association; similar claims later targeted HPV and COVID-19 vaccines.
- A political movement around health freedom, growing after attempts to end exemptions following the 2014–2015 Southern California measles outbreak, and extending opposition to masks, distancing and contact tracing during COVID-19.
- International expansion, including links with far-right and authoritarian movements in Canada, Western Europe, Africa, Brazil and Hungary.
Hotez described threats against scientists, including antisemitic abuse and Nazi imagery directed at Jewish scientists, amplified by political groups and media figures. He regarded these as an organised threat to biomedical infrastructure rather than random hostility.
Outbreaks and institutional distrust
The reactions to COVID-19 repeated a pattern seen with SARS in 2002, H1N1 in 2009 and MERS in 2012: a new pathogen appears, people assume the worst, and fear can outweigh reason. In April 2020, this was described as an infodemic of conspiracy theories, unsupported claims and false cures, amplified by social media and irresponsible health websites exploiting public anxiety. At least 300 deaths from methanol poisoning in Iran were reported after a false claim that drinking methanol cured COVID-19 circulated online.
The growth of social media and online interconnection provided fertile ground for misinformation and disinformation during the pandemic. Online disinformation had already served destabilising campaigns, but the pandemic brought a marked shift away from trust in institutions, scientific experts and their information. A 2024 warning anticipated foreign actors exploiting this legacy of distrust during the year's elections, when nearly 49% of the world's population was eligible to vote.