I just read the Carnegie-Mellon study on vaccine hesitancy and oddly enough it does not mention PhD's at all it talks about different occupations and age groups but not education levels. From the study this is the only reference to education I see:
"Final month (April 20-May 19) participants (N = 525,809) had a median age range of 35–44 years; 45.5% were male, 52.0% female, 1.3% non-binary, and 1.2% self-described gender; 16.7% were Hispanic, 68.8% White, 6.5% Black, 3.6% Asian, 0.9% Native American, 0.3% Pacific Islander, and 3.4% Multi-racial; 23.2% had ≤ high school education, 40.7% had ≥ four-year college; 13.4% lived in a non-core or micropolitan area, 50.4% lived in a large central or fringe metro area. Two-thirds (66.1%) worked for pay; half (50.6%) worked outside the home. Demographics were similar across all months (data not shown), including employment status. Compared to January, in May: 1.7% more participants reported working outside the home, while 1.2% fewer reported working at home, and 0.4% fewer reported not working for pay (eTable 2). "
"Final month (April 20-May 19) participants (N = 525,809) had a median age range of 35–44 years; 45.5% were male, 52.0% female, 1.3% non-binary, and 1.2% self-described gender; 16.7% were Hispanic, 68.8% White, 6.5% Black, 3.6% Asian, 0.9% Native American, 0.3% Pacific Islander, and 3.4% Multi-racial; 23.2% had ≤ high school education, 40.7% had ≥ four-year college; 13.4% lived in a non-core or micropolitan area, 50.4% lived in a large central or fringe metro area. Two-thirds (66.1%) worked for pay; half (50.6%) worked outside the home. Demographics were similar across all months (data not shown), including employment status. Compared to January, in May: 1.7% more participants reported working outside the home, while 1.2% fewer reported working at home, and 0.4% fewer reported not working for pay (eTable 2). "