IMPORTANCE Social distancing is critical to the control of COVID-19, which has disproportionately
affected the Black community. Physician-delivered messages may increase adherence to these
behaviors.
OBJECTIVES To determine whether messages delivered by physicians improve COVID-19
knowledge and preventive behaviors and to assess the differential effectiveness of messages
tailored to the Black community.
DESIGN, SETTING, AND PARTICIPANTS This randomized clinical trial of self-identified White and
Black adults with less than a college education was conducted from August 7 to September 6, 2020.
Of 44 743 volunteers screened, 30 174 were eligible, 5534 did not consent or failed attention checks,
and 4163 left the survey before randomization. The final sample had 20 460 individuals
(participation rate, 68%). Participants were randomly assigned to receive video messages on
COVID-19 or other health topics.
INTERVENTIONS Participants saw video messages delivered either by a Black or a White study
physician. In the control groups, participants saw 3 placebo videos with generic health topics. In the
treatment group, they saw 3 videos on COVID-19, recorded by several physicians of varied age,
gender, and race. Video 1 discussed common symptoms. Video 2 highlighted case numbers; in one
group, the unequal burden of the disease by race was discussed. Video 3 described US Centers for
Disease Control and Prevention social distancing guidelines. Participants in both the control and
intervention groups were also randomly assigned to see 1 of 2 American Medical Association
statements, one on structural racism and the other on drug price transparency.
MAIN OUTCOMES AND MEASURES Knowledge, beliefs, and practices related to COVID-19,
demand for information, willingness to pay for masks, and self-reported behavior.
RESULTS Overall, 18 223 participants (9168 Black; 9055 White) completed the survey (9980
[55.9%] women, mean [SD] age, 40.2 [17.8] years). Overall, 6303 Black participants (34.6%) and
7842 White participants (43.0%) were assigned to the intervention group, and 1576 Black
participants (8.6%) and 1968 White participants (10.8%) were assigned to the control group.
Compared with the control group, the intervention group had smaller gaps in COVID-19 knowledge
(incidence rate ratio [IRR], 0.89 [95% CI, 0.87-0.91]) and greater demand for COVID-19 information
(IRR, 1.05 [95% CI, 1.01-1.11]), willingness to pay for a mask (difference, $0.50 [95% CI, $0.15-$0.85]). Self-reported safety behavior improved, although the difference was not statistically significant (IRR,
0.96 [95% CI, 0.92-1.01]; P = .08). Effects did not differ by race (F = 0.0112; P > .99) or in different
intervention groups (F = 0.324; P > .99).
CONCLUSIONS AND RELEVANCE In this study, a physician messaging campaign was effective in
increasing COVID-19 knowledge, information-seeking, and self-reported protective behaviors among
diverse groups. Studies implemented at scale are needed to confirm clinical importance.