Table 4.
Incidence rates of hospitalization within 21 days of SARS-CoV-2 PCR test in vaccinated and 1-to-1 propensity-matched unvaccinated cohorts and corresponding vaccine effectiveness against COVID-19-related hospitalization
| Vaccine | Time period | Vaccinated incidence rate: Cases/person-days [per 1,000 person-days] (no. of individuals contributing) | Unvaccinated incidence rate: Cases/person-days [per 1,000 person-days] (no. of individuals contributing) | Incidence rate ratio (95% CI) | Vaccine effectiveness (95% CI) |
|---|---|---|---|---|---|
| BNT162b2 | on or after 7 days following the second dose | 7/1,915,615. [0.0037] (n = 35,990) | 60/1,837,276. [0.033] (n = 35,011) | 0.11 (0.043, 0.25) | 88.8% (75.5%, 95.7%) |
| on or after 14 days following the second dose | 6/1,671,628. [0.0036] (n = 33,963) | 49/1,599,076. [0.031] (n = 32,910) | 0.12 (0.041, 0.27) | 88.3% (72.6%, 95.9%) | |
| mRNA-1273 | on or after 7 days following the second dose | 9/948,311. [0.0095] (n = 16,369) | 63/932,315. [0.068] (n = 16,309) | 0.14 (0.061, 0.28) | 86.0% (71.6%, 93.9%) |
| on or after 14 days following the second dose | 5/833,681. [0.006] (n = 15,985) | 52/817,970. [0.064] (n = 15,896) | 0.094 (0.029, 0.23) | 90.6% (76.5%, 97.1%) |
Incidence rate is calculated as the number of individuals who were hospitalized within 21 days of their first positive PCR test per 1,000 person-days. Time period: time period relative to the first vaccine dose for the vaccinated cohort or study enrollment day for the unvaccinated cohort. Vaccinated incidence rate: number of individuals experiencing the outcome in the vaccinated cohort in the time period, divided by the number of at-risk person-days for the vaccinated cohort in the time period; in brackets, the number of cases per 1,000 person-days. Unvaccinated incidence rate: number of individuals experiencing the outcome in the propensity-matched unvaccinated cohort in the time period, divided by the number of at-risk person-days for the propensity-matched unvaccinated cohort in the time period; in brackets, the number of cases per 1,000 person-days. Incidence rate ratio: vaccinated incidence rate divided by unvaccinated incidence rate along with the exact 95% CI.16 Vaccine effectiveness: 100% × (1 − incidence rate ratio) along with the 95% CI.