Table 1. Characteristics of Individuals With Breakthrough Infection and Nonbreakthrough Infection in Cohort 1 During the Entire Study Period (March 1, 2020, to November 6, 2021).
| Characteristic | Breakthrough infection (n = 50) | Nonbreakthrough infection (n = 123)a | P value |
|---|---|---|---|
| Age, median (IQR), y | 46 (31-59) | 47 (33-59) | .80 |
| Sex, No. (%) | |||
| Male | 23 (46) | 50 (41) | .52 |
| Female | 27 (54) | 73 (59) | |
| Participant type, No. (%) | |||
| Health care worker | 42 (84) | 64 (52) | <.001 |
| Inpatient | 7 (14) | 33 (27) | |
| Guardian or caregiver | 1 (2) | 26 (21) | |
| Time from second vaccination to diagnosis, median (IQR), d | 98 (57-143) | NA | NA |
| Type of COVID-19 vaccine, No. (%) | |||
| ChAdOx nCoV-19 | 40 (80) | NA | NA |
| BNT162b2 | 5 (10) | NA | |
| mRNA-1273 | 2 (4) | NA | |
| Heterologousb | 2 (4) | NA | |
| Otherc | 1 (2) | NA | |
| Symptomatic at diagnosis, No. (%) | 38 (76) | 82 (67) | .23 |
| Time from symptom onset to diagnosis, median (IQR), d | 1 (0-1) | 1 (0-3) | .06 |
| Ct value at diagnosis, median (IQR) | 19 (16-24)d | 20 (15-29)e | .64 |
| Nosocomial secondary transmission, No./total No. (%)f | 3/43 (7) | 29/110 (26) | .008 |
Abbreviations: Ct, cycle threshold; mRNA, messenger RNA; NA, not applicable.
a
Including 15 partially vaccinated individuals.
b
ChAdOx1 nCoV-19 followed by BNT162b2.
c
rAD26 and rAd5 vector–based vaccine.
d
Including 45 individuals who underwent SARS-CoV-2 testing at our hospital; Ct values were unavailable in the remaining 5 individuals.
e
Including 103 individuals who underwent SARS-CoV-2 testing at our hospital; Ct values were unavailable in the remaining 20 individuals.
f
Excluding individuals who were diagnosed during quarantine (7 in the breakthrough infection group and 13 in the nonbreakthrough infection group).