After a back-and-forth between the Trump and Biden campaigns led to President Donald Trump falsely accusing Democratic nominee for vice president Kamala Harris of undermining confidence in a potential vaccine for COVID-19, mainstream news outlets often failed to note that Trump has a long history of spreading conspiracy theories about vaccines.

The timing of a COVID-19 vaccine has become a campaign issue largely because of Trump’s repeated suggestion of the incredibly unlikely prospect that a vaccine will be ready before the November 3 elections. According to The Washington Post, Trump has increasingly connected a pre-Election Day vaccine approval to his reelection chances. Responding to concerns about federal government pressure to rush a vaccine, nine major vaccine developers have signed a pledge to seek government approval for a COVID-19 vaccine only “after demonstrating safety and efficacy through a Phase 3 clinical study.” This pledge makes an approved vaccine by Election Day a near impossibility based on how far the leading vaccine contenders are presently in their trials. 

During a September 5 interview with CNN, Harris was asked about Trump’s vaccine timing claims. She responded that she would “not trust Donald Trump” on the efficacy of a COVID-19 vaccine released before Election Day but that she would trust “a credible source of information that talks about the efficacy and the reliability” of the vaccine. This prompted a dishonest attack from Trump against Harris that claimed she was using “reckless anti-vaccine rhetoric.” In fact, Harris’ concern that political pressures could lead pharmaceutical companies to release a vaccine before it is ready is shared by a strong majority of Americans of all political persuasions.

Some mainstream news outlets credulously adopted Trump’s attack in their headlines, even though Harris only criticized Trump’s credibility on the issue (where he has demonstrated he has none) and not the push to develop a COVID-19 vaccine generally. 

The Hill:

NBC News:

The Boston Herald gave no context in its headline to Trump’s incredibly improbable claim of a COVID-19 vaccine becoming available in October:

A more prevalent pattern in mainstream press coverage, however, was its failure to provide context on Trump’s historical position on vaccines. As early as in 2007, Trump frequently promoted the discredited claim that there is a connection between vaccines and autism in children. In fact, on Autism Awareness Day in 2012, Trump called into Fox News program Fox & Friends to falsely claim vaccines had caused an “epidemic” of autism. 

Before he took office as president, Trump invited anti-vaccine activist and conspiracy theorist Robert F. Kennedy Jr. to chair a government commission on vaccines, though the plan appears to have never materialized. (As of late, Kennedy has been spending his time pushing unhinged conspiracy theories about 5G cell phone technology supposedly causing coronavirus and attacking the development of a COVID-19 vaccine.) And a May 2020 study published in the Journal of Experimental Social Psychology found that the numerous anti-vaccine tweets that Trump has sent led to significantly increased negative attitudes toward vaccines among his supporters -- an important context to his reckless suggestion of COVID-19 vaccine availability by Election Day. 

But Trump’s history of damaging public health attitudes toward vaccines was omitted from articles about the recent exchanges between the Trump and Biden campaigns in The Hill, Politico, The Boston Herald, the Associated Press (republished by The Washington Post and The New York Times) and CNN.