Vaccine misinformation is more likely on social media

The study, based on nationally representative surveys of nearly 2,500 US adults, found that up to 20 per cent of respondents were at least somewhat misinformed about vaccines.

Such a high level of misinformation is "worrying" because misinformation undermines vaccination rates, and high vaccination rates are required to maintain community immunity, the researchers said.

"People who received their information from traditional media were less likely to endorse anti-common vaccination claims," said study lead author Dominik Stecula from University of Pennsylvania in the US.

The findings, published in the Harvard Kennedy School Misinformation Review, was conducted in the spring and fall of 2019, when the US experienced its largest measles outbreak in a quarter century.

Between the two survey periods, 19 per cent of the respondents' levels of vaccine misinformation changed in a substantive way - and within that group, almost two-thirds (64 per cent) were more misinformed in the fall than in the spring.

The researchers found that 18 per cent of respondents mistakenly said that it is very or somewhat accurate to state that vaccines cause autism; 15 per cent mistakenly agreed that it is very or somewhat accurate to state that vaccines are full of toxins.

The researchers also found that an individual's level of trust in medical experts affects the likelihood that a person's beliefs about vaccination will change.

Low levels of trust in medical experts coincide with believing vaccine misinformation, the researchers said.

The findings come as a number of states have been debating whether to tighten their laws surrounding vaccination exemptions and social media companies have been wrestling with how to respond to different forms of misinformation.

The result is consistent with research suggesting that social media contain a fair amount of misinformation about vaccination while traditional media are more likely to reflect the scientific consensus on its benefits and safety, according to the researchers.