Table 2.
Baseline Characteristics of Study Participants by Study Arm (N=1,093 total)
| Characteristica | Vaccine social media arm (n=542) | Vaccine information arm (n=371) | Usual care arm (n=180) |
|---|---|---|---|
|
| |||
| Mother’s age at enrollment, years, M (SD) | 31.6 (4.4) | 31.5 (4.3) | 31.4 (4.1) |
| Mother’s race, n (%)b | |||
| White | 476 (87.8) | 315 (84.9) | 159 (88.3) |
| Black | 12 (2.2) | 8 (2.2) | 4 (2.2) |
| Asian/Pacific Islander | 21 (3.9) | 19 (5.1) | 4 (2.2) |
| Multi-racial/other | 31 (5.7) | 27 (7.3) | 12 (6.7) |
| Missing | 2 (0.4) | 2 (0.5) | 1 (0.6) |
| Mother’s ethnicity, n (%)b | |||
| Hispanic | 47 (8.7) | 48 (12.9) | 22 (12.2) |
| Non-Hispanic | 489 (90.2) | 321 (86.5) | 155 (86.1) |
| Missing | 6 (1.1) | 2 (0.5) | 3 (1.7) |
| Number of children, n (%)b | |||
| Pregnant with first child | 246 (45.4) | 189 (50.9) | 83 (46.1) |
| Have other child/children | 296 (54.6) | 181 (48.8) | 96 (53.3) |
| Missing | 0 (0) | 1 (0.3) | 1 (0.6) |
| Annual household income, n (%)b | |||
| <$40,000 | 45 (8.3) | 35 (9.4) | 15 (8.3) |
| $40,000–$80,000 | 163 (30.1) | 122 (32.9) | 60 (33.3) |
| $81,000–$120,000 | 188 (34.7) | 103 (27.8) | 57 (31.7) |
| >$120,000 | 118 (21.8) | 91 (24.5) | 40 (22.2) |
| Decline to answer/missing | 28 (5.2) | 20 (5.4) | 8 (4.4) |
| Mother’s education, n (%)b | |||
| High school or less | 21 (3.9) | 14 (3.8) | 2 (1.1) |
| Some college | 72 (13.3) | 49 (13.2) | 28 (15.6) |
| College | 222 (41.0) | 136 (36.7) | 72 (40.0) |
| Graduate school | 227 (41.9) | 171 (46.1) | 77 (42.8) |
| Missing | 0 (0) | 1 (0.3) | 1 (0.6) |
| Use of Internet for health, n (%)b | |||
| Not at all | 11 (2.0) | 5 (1.3) | 3 (1.7) |
| Once a month or less | 199 (36.7) | 135 (36.4) | 57 (31.7) |
| Every week | 272 (50.2) | 199 (53.6) | 100 (55.6) |
| Every day | 60 (11.1) | 31 (8.4) | 19 (10.6) |
| Missing | 0 (0) | 1 (0.3) | 1 (0.6) |
| Vaccine hesitancy by PACV,c median (IQR) | 13.0 (26.0) | 17.0 (34.0) | 15.0 (31.5) |
a
No significant differences in characteristics across study arms (all p-values ≥0.15).
b
Percentages represent column percentages.
c
PACV, a validated screening questionnaire assessing vaccine hesitancy on a scale from 0 to 100; higher scores indicate a higher degree of hesitancy.
IQR, interquartile range; PACV, Parent Attitudes and Childhood Vaccines.