Those with symptoms of depression more likely to believe vaccine misinformation: study

TORONTO -

Adults with moderate to major symptoms of depression appear more likely to support false statements about COVID-19 vaccines and those who believe the misinformation have a higher probability of not being vaccinated, a new Harvard University-led study suggests.

The paper, published on Friday in JAMA Network Open, analyzed data from 15,464 responses between May and July 2021 in two waves of an ongoing internet survey project. The results add to a growing body of research, particularly amid COVID-19, examining how and why misinformation spreads. Previous research has found that about a quarter of adults in the U.S. have shown moderate or stronger symptoms of depression during the pandemic, which can contribute to negativity bias.

“A general bias toward negativity in information selection, processing, and recall may exacerbate misinformation exposure. In the context of political misinformation, both anger and anxiety are associated with promoting beliefs in certain types of false stories,” researchers wrote.

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Respondents, who also completed a patient health questionnaire to measure their depressive symptoms in the previous two weeks, were asked their vaccination status and questions that included four statements about the vaccine that were not true: “The COVID-19 vaccines will alter people’s DNA,” “The COVID-19 vaccines contain microchips that could track people,” “The COVID-19 vaccines contain the lung tissue of aborted fetuses,” and “The COVID-19 vaccines can cause infertility, making it more difficult to get pregnant.” Respondents were asked to rate the statements as accurate, inaccurate, or not sure.

To ensure the survey did not contribute to the spread of misinformation, respondents were told which statements were not true at the end of the survey section.

Participants did not know they were completing a survey focused on COVID-19 to mitigate selection bias. The survey used nonprobability sampling, meaning the participants chose to participate and were not randomly selected. To mitigate this issue, self-reported details on age, gender, ethnicity, education, zip codes, and other factors were reweighted to approximate the adult population in each state.

The survey study found that signs of depression were tied to an increased likelihood of believing misinformation, with those who believed at least one piece of false information on vaccines also “significantly less likely” to be vaccinated and more likely to be resistant to vaccination.

In an analysis adjusted to reflect the U.S. population, 29.3 per cent of survey participants who had moderate or worse symptoms of depression believed misinformation compared with 15.1 per cent of those who had no symptoms.

More than 2,800 respondents also answered the survey again in July, and those who showed signs of depression in the first survey appeared to have a greater likelihood of endorsing even more false statements compared with the first survey.

While mistrust in institutions may be another potential factor, the authors also found that modelling to examine that relationship did not change the main findings associated with depression.

The study’s design did not look at whether depression caused an individual to believe in misinformation, the scientists said, adding that the association merited further study. It was possible that those with depression were more prone to use certain types of social media, that those platforms could be more likely to promote misinformation, and that social media use could promote both depression and misinformation independently, researchers wrote in the study.

“As anticipated, we also found that individuals who embraced health misinformation were less likely to be vaccinated or be willing to get the vaccine if available. As such, individuals already burdened with depression may be at a higher risk of COVID-19,” the paper said.

“It bears noting that individuals with depression may also exhibit a lack of positive interpretation bias, ie, less optimistic beliefs, which could lead them to underestimate the potential benefit of vaccination. Notably, mood disorders have been associated with worse COVID-19 outcomes among hospitalized patients.”