Table 1.
Sensitivity analysis of RT-PCR test-positive rate after close contact by the elapsed days from the last vaccination and age groups.
| Completed vaccine doses | Elapsed days from the last vaccination | All RT-PCR tested participants (n) | RT-PCR test-positive (n) | RT-PCR test positivity rate (%; 95% CI) | RR (95% CI) vs. zero dose group | RR (95% CI) vs. two doses group |
|---|---|---|---|---|---|---|
| Not vaccinated | Total | 139 | 68 | 48.9% (40.8–57.2) | Reference (1.0) | – |
| (18–64 years old) | 135 | 68 | 50.4% (42.0–58.7) | – | – | |
| (≥ 65 years old) | 4 | 0 | – | – | – | |
| Two doses (total) | 7–90 days | 40 | 15 | 37.5% (24.2–53.0) | 0.77 (0.50–1.18) | Reference (1.0) |
| 91–180 days | 352 | 164 | 46.6% (41.4–51.8) | 0.95 (0.78–1.17) | Reference (1.0) | |
| ≥ 181 days | 201 | 93 | 46.3% (39.5–53.2) | 0.95 (0.76–1.19) | – | |
| (18–64 years old) | 7–90 days | 39 | 15 | 38.5% (24.9–54.1) | 0.79 (0.51–1.21) | Reference (1.0) |
| 91–180 days | 351 | 163 | 46.4% (41.3–51.7) | 0.95 (0.77–1.16) | Reference (1.0) | |
| (≥ 65 years old) | 7–90 days | 1 | 0 | – | – | – |
| 91–180 days | 1 | 1 | – | – | – | |
| Three doses (total) | 7–90 days | 150 | 43 | 28.7% (22.0–36.4) | 0.59 (0.43–0.79) | 0.76 (0.48–1.23) |
| 91–180 days | 13 | 7 | 53.9% (29.2–76.8) | 1.10 (0.65–1.87) | 1.16 (0.69–1.94) | |
| ≥ 181 days | None | None | – | – | – | |
| (18–64 years old) | 7–90 days | 108 | 35 | 32.4% (24.3–41.7) | 0.66 (0.48–0.91) | 0.84 (0.52–1.36) |
| 91–180 days | 11 | 7 | 63.6% (35.4–84.8) | 1.30 (0.81–2.10) | 1.37 (0.87–2.17) | |
| (≥ 65 years old) | 7–90 days | 42 | 8 | 19.1% (10.0–33.3) | 0.39 (0.20–0.74) | – |
| 91–180 days | 2 | 0 | – | – | – |
RT-PCR test positivity rate after close contact with COVID-19 cases among adults aged ≥ 18 years, stratified by age groups (18–64 years / ≥ 65 years) and elapsed days from the last vaccination (7–90 days, 91–180 days, and ≥ 181 days) are shown.
CI confidence interval, RR risk ratio, RT-PCR reverse transcription polymerase chain reaction.