Table 1.
Baseline characteristics and 1-year vaccine intake, 2021–2022, Japan.
| Distribution | Received 1+ Dose of the COVID-19 Vaccine During the 1-Year Observation Window | ||
|---|---|---|---|
| Baseline Characteristics | N (%) | % (SE) | APR (95% CI) |
| Total | 19,482 (100.0%) | 81.6 (0.5) | - |
| Vaccination status (number of COVID-19 vaccine doses completed before/at baseline) |
|||
| 0 | 3155 (18.1%) | 36.5 (1.4) | Ref. |
| 1 | 1579 (9.0%) | 97.4 (0.8) | 2.64 (2.45–2.84) |
| 2 | 14,748 (72.9%) | 91.0 (0.4) | 2.38 (2.21–2.56) |
| Mask-wearing | |||
| No | 1558 (9.1%) | 67.5 (2.0) | 0.95 (0.90–1.001) |
| Yes | 17,924 (90.9%) | 83.0 (0.5) | Ref. |
| Avoidance of risky situations (number of the “three Cs” avoided) |
|||
| 0 | 4162 (23.5%) | 76.1 (1.1) | 0.97 (0.94–0.99) |
| 1 | 4399 (22.8%) | 81.0 (0.9) | 0.98 (0.95–1.002) |
| 2 | 5221 (26.2%) | 82.9 (0.9) | 0.97 (0.95–0.99) |
| 3 | 5700 (27.4%) | 85.6 (0.7) | Ref. |
| Fear of COVID-19-induced death | |||
| No | 11,780 (59.9%) | 78.8 (0.6) | Ref. |
| Yes | 7702 (40.1%) | 85.8 (0.6) | 1.05 (1.03–1.07) |
| Underlying medical conditions | |||
| Not present | 13,166 (67.1%) | 79.1 (0.6) | Ref. |
| Present | 6316 (32.9%) | 86.8 (0.8) | 1.03 (1.01–1.05) |
| Ever diagnosed with COVID-19 | |||
| No | 19,182 (98.3%) | 81.7 (0.5) | Ref. |
| Yes | 300 (1.7%) | 76.3 (4.4) | 1.01 (0.90–1.14) |
| Smoking status | |||
| Never | 10,667 (55.8%) | 80.9 (0.6) | Ref. |
| Former | 6023 (28.7%) | 85.1 (0.8) | 0.99 (0.97–1.01) |
| Current | 2792 (15.4%) | 77.6 (1.2) | 0.96 (0.93–0.99) |
| Current use of heated tobacco products | |||
| No | 17,817 (90.6%) | 81.6 (0.5) | Ref. |
| Yes | 1665 (9.4%) | 81.7 (1.5) | 1.02 (0.98–1.06) |
| Current alcohol drinking | |||
| No | 9173 (62.0%) | 80.0 (0.7) | Ref. |
| Yes | 10,309 (38.0%) | 84.2 (0.6) | 1.03 (1.01–1.05) |
| Sex | |||
| Female | 9751 (50.5%) | 81.7 (0.7) | Ref. |
| Male | 9731 (49.5%) | 81.5 (0.6) | 1.01 (0.99–1.03) |
| Age, years old | |||
| 16–64 | 13,870 (72.6%) | 78.0 (0.6) | Ref. |
| 65+ | 5612 (27.4%) | 91.1 (0.7) | 1.07 (1.05–1.10) |
| Education | |||
| Some college/college or higher | 13,875 (47.8%) | 81.9 (0.5) | Ref. |
| High school or less | 5506 (52.2%) | 81.6 (0.7) | 0.99 (0.97–1.01) |
| Employment status | |||
| Full time | 7199 (35.8%) | 82.2 (0.7) | Ref. |
| Self-employed | 1384 (6.7%) | 72.5 (2.0) | 1.03 (1.002–1.06) |
| Part time | 3798 (21.1%) | 80.3 (1.0) | 0.95 (0.92–0.99) |
| Unemployed | 7101 (36.4%) | 83.5 (0.8) | 1.03 (1.004–1.06) |
Abbreviations: APR = adjusted prevalence ratio, CI = confidence interval, COVID-19 = coronavirus disease 2019, three Cs = closed spaces, crowded places, and close-contact settings, SE = standard error. Note: Data were extracted from the Japan COVID-19 and Society Internet Survey (JACSIS), a nationwide, self-reported survey and were weighted to account for the selectivity bias of the Internet-based sample using a nationally representative sample as the reference. APRs and CIs were computed by multivariable Poisson regression analysis.