off label.

Misinformation

Does exposure to misinformation actually change health behavior, or does it just correlate with belief?

A small set of accounts drives an outsized share of anti-vaccine content, which major platforms amplify to tens of millions of followers. Belief in false health claims rises sharply among some partisan-media audiences, and the downstream harm, from lower vaccination intent to delayed cancer treatment, is measurable but comes from different study designs that do not compare cleanly.

Question

The problem

Health misinformation is a public-health operating risk because it can change patient behavior, strain clinicians, and reduce uptake of effective care. The landscape problem is uneven exposure: false claims concentrate in specific audiences, channels, and repeat sources, while evidence of harm varies by study design.

The recommendation

Build a targeted misinformation response rather than a generic messaging campaign. The recommended model is to identify high-reach sources and high-belief audiences, deploy trusted messengers where exposure is concentrated, and separate causal evidence from correlation when prioritizing interventions.

The belief

How widespread belief in false health claims is, and which audiences carry it most.

45%
of US adults believe at least one tested false health claim
Across 10 tested false claims on COVID-19 vaccines, reproductive health, and gun safety (2023).
76%
of regular Newsmax viewers believe at least one false COVID-19 or vaccine claim
Versus 45 percent of all US adults. Belief concentrates in specific partisan-media audiences.

Belief in at least one false COVID-19 or vaccine claim, by news audience

Share of adults who say at least one tested false COVID-19 or vaccine claim is definitely or probably true. The reference line is all US adults at 45 percent.

Read it this way Belief in false COVID-19 or vaccine claims among regular Newsmax viewers, 76 percent, sits 31 percentage points above the 45 percent baseline for all US adults, with OANN and Fox News audiences also well above that line. Because these audience figures come from KFF's narrative summary rather than a full data table, treat the ranking as reliable but the exact percentages as approximate. Use this chart to see whether it shows exposure, belief, spread, or harm, and why the recommendation focuses on targeted response rather than broad undifferentiated messaging.

Caveat The audience figures come from KFF's written summary of the poll (Newsmax 76, OANN 67, Fox 61 versus 45 overall), not a structured data table.

0% 25% 50% 75% 100% Regular Newsmax viewers 76% Regular OANN viewers 67% Regular Fox News viewers 61% All US adults 45% all US adults (45%)
⊞ data table⬇ CSV
AudienceBelieve at least one false claim (percent)
Regular Newsmax viewers76
Regular OANN viewers67
Regular Fox News viewers61
All US adults45

KFF Health Misinformation Tracking Poll Pilot · 2023 · source

The spread

The supply side: a few superspreader accounts, and how content travels from origin to mass reach.

73%
of tracked Facebook anti-vaccine shares trace to just 12 accounts
502,970 of 689,000 tracked shares, February to March 2021 (CCDH).
59.2M
combined follower reach of the tracked anti-vaccine ecosystem
A broader 425-account universe as of December 2020, a different snapshot than the share counts.

Share of tracked anti-vaccine content from 12 accounts versus everyone else, by platform

Tracked anti-vaccine content shares from February 1 to March 16, 2021. The Disinformation Dozen are 12 accounts. On Facebook they account for 73 percent of tracked shares, on Twitter/X only 17 percent.

Read it this way On Facebook, the twelve Disinformation Dozen accounts alone produced more shares (502,970) than every other tracked anti-vaccine account combined (186,030), the opposite of the Twitter/X pattern, where they contribute only 20,400 of 120,000 tracked shares. Platform concentration of anti-vaccine content is not uniform. It is far worse on Facebook, though the account-level attribution is CCDH's own, not an independently audited count. Use this chart to see whether it shows exposure, belief, spread, or harm, and why the recommendation focuses on targeted response rather than broad undifferentiated messaging.

Caveat The 502,970 and 20,400 figures are CCDH's published shares (689,000 Facebook, 120,000 Twitter/X) split by its stated 73 percent and 17 percent Disinformation Dozen attributions. Other-account values are the remainder.

0 250,000 500,000 750,000 1,000,000 FacebookTwitter/X Disinformation Dozen (12 accounts) Other anti-vaccine accounts
⊞ data table⬇ CSV
PlatformDisinformation Dozen sharesOther-account sharesTotal tracked shares
Facebook502970186030689000
Twitter/X2040099600120000

Center for Countering Digital Hate, The Disinformation Dozen · 2021 · source

How anti-vaccine content moved across platforms, Feb 1 to Mar 16 2021

Tracked share counts flowing from originating accounts through each platform to the combined tracked total. A small group of twelve accounts accounted for up to 73 percent of tracked Facebook shares.

Read it this way Follow the Disinformation Dozen node: it feeds 502,970 of the 689,000 Facebook shares but only 20,400 of the 120,000 Twitter/X shares, so the same twelve accounts have very different reach depending on platform. The diagram traces only these two platforms' tracked shares and excludes the broader 425-account, 59.2 million-follower ecosystem CCDH measured on a separate timeframe. Use this chart to see whether it shows exposure, belief, spread, or harm, and why the recommendation focuses on targeted response rather than broad undifferentiated messaging.

Caveat Anti-vaccine content is used here as the one publicly documented case study with real figures. The 425-account ecosystem CCDH tracked reached a combined 59.2 million followers as of December 2020, a follower-reach figure on a different scale and snapshot than these share counts, so it is not drawn as a flow link.

Disinformation Dozen (12 accounts) 523,370 Other anti-vaccine accounts 285,630 Facebook 689,000 Twitter/X 120,000 All tracked platforms 809,000
⊞ data table⬇ CSV
FromToTracked shares
Disinformation Dozen (12 accounts)Facebook502970
Other anti-vaccine accountsFacebook186030
Disinformation Dozen (12 accounts)Twitter/X20400
Other anti-vaccine accountsTwitter/X99600
FacebookAll tracked platforms689000
Twitter/XAll tracked platforms120000

Center for Countering Digital Hate, The Disinformation Dozen · 2021 · source

The harm

Downstream evidence in two honest halves: behavior change from a randomized experiment, and outcome severity from observational studies. The three harm metrics come from different designs and do not compare cleanly.

-6.4pp
drop in US COVID-19 vaccination intent after exposure to real misinformation
The UK fell 6.2 points. Randomized experiment of 8,001 adults (Loomba et al. 2021).
2.50×
higher risk of death for cancer patients who chose alternative medicine over proven treatment
Overall adjusted hazard ratio. Breast cancer reached 5.68 times. Observational cohort (Johnson et al. 2018).
23,005
emergency-department visits a year from dietary-supplement adverse events
Including about 2,154 hospitalizations. This is supplement-harm burden generally, not a misinformation-attribution estimate.

COVID-19 vaccination intent before and after exposure to real misinformation

Stated intent to accept a vaccine, before and after adults were shown real circulating misinformation, in a randomized experiment of 8,001 US and UK adults. Intent fell about 6 percentage points in both countries.

Read it this way Stated vaccination intent fell by nearly the same amount in both countries, 6.4 points in the US and 6.2 points in the UK, even though the UK started from a higher baseline of 54.1 percent versus 42.5 percent. Because this came from a randomized experiment, the drop can be read as a causal effect of the misinformation shown, within the reported uncertainty range of roughly 4 to 9 points, not just an association. Use this chart to see whether it shows exposure, belief, spread, or harm, and why the recommendation focuses on targeted response rather than broad undifferentiated messaging.

Caveat The baselines (42.5 percent US, 54.1 percent UK) and the modeled declines (6.4 points US, 6.2 points UK) come from Loomba et al. 2021. Post-exposure values are the baseline minus the modeled drop. The 95 percent uncertainty intervals are 8.8 to 4.0 points (US) and 8.5 to 3.9 points (UK).

0.0% 25.0% 50.0% 75.0% 100.0% 42.5% 36.1% United States 54.1% 47.9% United Kingdom Before exposure After exposure
⊞ data table⬇ CSV
CountryBefore exposure (percent)After exposure (percent)Change (percentage points)
United States42.536.1-6.4
United Kingdom54.147.9-6.2

Nature Human Behaviour, COVID-19 vaccine misinformation and intent · 2021 · source

Risk of death after using alternative medicine instead of proven cancer treatment

Adjusted hazard ratio for death versus matched patients treated conventionally. A value of 1.0 means equal risk, and the overall figure of 2.50 means the risk of death roughly doubled.

Read it this way Breast cancer patients who chose alternative medicine faced the highest risk shown here, a hazard ratio of 5.68, more than double the 2.5 overall figure, while the prostate cancer estimate of 1.68 did not reach statistical significance and should not be read as a real effect. These ratios come from one matched cohort of 281 alternative-medicine patients versus 560 conventionally treated patients, so read them as evidence within this study, not a universal harm multiplier for every alternative-medicine choice. Use this chart to see whether it shows exposure, belief, spread, or harm, and why the recommendation focuses on targeted response rather than broad undifferentiated messaging.

Caveat Modeled hazard ratios from one National Cancer Database cohort (281 alternative-medicine patients matched to 560 conventionally treated patients, 2004 to 2013), not a count of deaths. The prostate figure was not statistically significant. Harm estimates across misinformation topics use different study designs and do not compare cleanly.

0.00× 2.50× 5.00× 7.50× 10.00× Breast cancer 5.68× Colorectal cancer 4.57× Lung cancer 2.17× Prostate cancer (not significant) 1.68× All cancers (overall) 2.50× equal risk (1.0)
⊞ data table⬇ CSV
Cancer typeHazard ratio for death95% confidence interval
Breast5.683.22 to 10.04
Colorectal4.571.66 to 12.61
Lung2.171.42 to 3.32
Prostate1.68not statistically significant
All cancers (overall)2.51.88 to 3.27

Journal of the National Cancer Institute, alternative medicine and survival · 2018 · source

Why this matters

Concentration is the throughline: in belief, in the amplifying accounts, and in which platform amplification is worst. The clearest harm evidence is the randomized vaccine-intent experiment, which supports a causal read within its reported uncertainty range of roughly 4 to 9 points. The alternative-medicine hazard ratios and supplement emergency-department counts are real but come from different, non-comparable study designs, and none of them establish that misinformation specifically, rather than health decisions generally, caused those outcomes. That caveat rides with each chart.

Recommended actions

  • Prioritize platform enforcement on repeat superspreader accounts rather than individual posts, especially on platforms where concentration is highest.
  • Target counter-messaging at the specific media audiences with elevated belief rather than the general public, since belief is concentrated, not uniform.
  • Disclose the uncertainty range (roughly 4 to 9 percentage points) whenever citing the vaccine-intent effect size, rather than a single point estimate.
  • Do not combine the alternative-medicine hazard ratios, the supplement adverse-event count, and the vaccine-intent drop into one combined harm figure. They use incompatible study designs and should be reported separately.
  • Monitor account-level concentration over time using platform transparency reports, since the 2021 snapshot may not hold today.

The recommendation

Therefore, build a targeted misinformation response rather than a generic messaging campaign. The recommended model is to identify high-reach sources and high-belief audiences, deploy trusted messengers where exposure is concentrated, and separate causal evidence from correlation when prioritizing interventions.

Demographic slice none. Platform transparency reports and harm studies are topic/platform-level.

Sources