He has given credence to the vaccine-autism link early in the 2016 debates and in tweets.
He was also instrumental in pushing early treatments that didn't pan out as hoped. These often became the subject of conspiracy theories about a whole slew of medical professionals avoiding real treatment, and the pandemic being some authoritarian plot. Trump was there sowing doubt in medical professionals. He may have encouraged vaccination itself, but his actions on the whole produced distrust so that there is a pronounced deficit of vaccination in his electorate.
He was also instrumental in pushing early treatments that didn't pan out as hoped. These often became the subject of conspiracy theories about a whole slew of medical professionals avoiding real treatment, and the pandemic being some authoritarian plot. Trump was there sowing doubt in medical professionals. He may have encouraged vaccination itself, but his actions on the whole produced distrust so that there is a pronounced deficit of vaccination in his electorate.