Trump’s tweets influence anti-vaxxers

16 Mar 2020

Trump supporters are more likely to believe conspiracy theories and hold anti-vaccination views, a University of Queensland study on American internet users has found.

TrumpUQ researcher Professor Matthew Hornsey said Mr Trump had sent dozens of tweets linking vaccinations with autism before he became President, despite this link being a long-discredited myth.

“Trump supporters are considerably more vaccine-hesitant than other Americans, and are more likely to be concerned about side-effects,” Professor Hornsey said.

The research team also asked 518 Americans to what extent they believed famous conspiracy theories, such as suggestions Diana, Princess of Wales, was murdered and the September 11 attacks were an inside job organised by the Bush administration.

The team found Trump voters were more likely to believe these conspiracy theories than other Americans.

“There’s a certain conspiratorial worldview held by Trump voters that makes them more likely to be anti-vaccination,” Professor Hornsey said.

“Conspiracy theorists do not trust the official word on vaccination.

“They think the government or the drug companies are lying, or both.

“Trump has spread several conspiracy theories in the past, including that Barack Obama faked his birth certificate, that climate change is a hoax invented by the Chinese and Ted Cruz’s father helped assassinate JFK,” he said.

The research team conducted further studies to test if reading Mr Trump’s old anti-vaxx tweets still had an impact on the public.

“Trump voters became more anti-vaxx after reading his old tweets but they had no effect on anyone else,” Professor Hornsey said.

Trump has stopped making anti-vaxx statements since he became President and last year encouraged parents to vaccinate their children in the face of a measles outbreak.

“We’re hoping this is a permanent change of heart,” Professor Hornsey said.

“Every President since Roosevelt has swung behind the science on vaccination, and it’s promising that Trump appears to have turned a corner on this issue because his words can save lives.”

This research was a collaboration between UQ’s School of Psychology and the University of Exeter.

The study is published in the Journal of Experimental Social Psychology (DOI: 10.1016/j.jesp.2019.103947).

Media: Professor Matthew Hornsey,; Dani Nash, UQ Communications,, +61 7 3346 3035.