Table 3. Summary of studies on coronavirus disease 2019 vaccine effectiveness in Korea.
| Studies | Study period | Predominant viral strain | Study population | Comparators | Vaccine effectiveness (95% CI) | Reference |
|---|---|---|---|---|---|---|
| Yi et al. | Mar 2021–Oct 2021 | Alpha, delta | General population | Unvaccinated vs. primary series | Laboratory-confirmed infection: 63%a | [44] |
| Severe infection: 93%a | ||||||
| Death: 95%a | ||||||
| Kim et al. | May 2021 | Alpha | LTCF residents, staff and caregivers | Unvaccinated vs. first-dose ChAdOx1 nCoV-19 | Laboratory-confirmed infection: 95.3% (67.7–99.3%) | [45] |
| Kim et al. | Oct 2021–Jan 2022 | Delta | General population aged 60+ | Primary series vs. first booster (third dose) | Symptomatic infection: 75.0% (74.1–75.8%) | [46] |
| Severe infection: 91.6% (89.2–93.4%) | ||||||
| Park et al. | Feb 2022–Apr 2022 | Omicron (BA.1) | LTCF residents and staff | Unvaccinated vs. first booster (third dose) | Severe infection: 71% (36–87%) | [47] |
| Death: 65% (21–85%) | ||||||
| Kim et al. | Feb 2022–Apr 2022 | Omicron (BA.1) | Healthcare workers | Primary series vs. first booster | Laboratory-confirmed infection: 53.1% (13–75%) | [50] |
| Kim et al. | Feb 2022–May 2022 | Omicron (BA.1) | Immunocompromised persons, LTCF residents | First booster vs. second booster | Laboratory-confirmed infection: 21.0% (20.1–21.8%) | [37] |
| Severe infection: 50.5% (44.0–56.3%) | ||||||
| Death: 54.1% (47.3–60.0%) | ||||||
| Choe et al. | Jul 2021–Aug 2021 | Delta | 18-year-old | Unvaccinated vs. primary series | Laboratory-confirmed infection: 99.1% (98.5–99.5%) | [53] |
CI = confidence interval, LTCF = long-term care facility.
a95% CI not reported.