Table 2.
Adjusted Incidence Rate Ratios (IRRs) for Symptomatic PCR-Confirmed SARS-CoV-2 Infection and Any PCR-Positive Result (Symptomatic or Asymptomatic) by Antibody and Vaccine Status
| Variable | Symptomatic PCR-confirmed Infection | Any PCR-positive Result | |||||
|---|---|---|---|---|---|---|---|
| Adjusted IRR | 95% CI | P value | Adjusted IRR | 95% CI | P value | ||
| Age | Age, per 10 y increase | 0.92 | .84–1.02 | .10 | 0.99 | .99–1.00 | .07 |
| Sex | Female (reference) | 1.00 | 1.00 | ||||
| Male | 1.11 | .85–1.44 | .46 | 1.08 | .90–1.31 | .41 | |
| Patient facing role | No (reference) | 1.00 | 1.00 | ||||
| Yes | 1.06 | .76–1.49 | .72 | 1.13 | .90–1.42 | .29 | |
| Covid ward | Not working in Covid ward | 1.00 | 1.00 | ||||
| Working in non-ICU Covid ward | 1.57 | 1.11–2.21 | .01 | 1.53 | 1.21–1.94 | <.001 | |
| Month | April—July 2020 (reference) | 1.00 | 1.00 | ||||
| August 2020 | 0.51 | .19–1.33 | .17 | 0.20 | .09–0.42 | <.001 | |
| September 2020 | 0.51 | .20–1.35 | .18 | 0.31 | .17–.58 | <.001 | |
| October 2020 | 2.02 | 1.13–3.63 | .02 | 1.01 | .69–1.48 | .96 | |
| November 2020 | 5.34 | 3.30–8.62 | <.001 | 2.92 | 2.20–3.87 | <.001 | |
| December 2020 | 9.23 | 5.89–14.50 | <.001 | 5.91 | 4.60–7.59 | <.001 | |
| January 2021 | 14.60 | 9.24–23.00 | <.001 | 7.93 | 6.10–10.30 | <.001 | |
| February 2021 | 7.10 | 3.89–13.00 | <.001 | 3.72 | 2.54–5.46 | <.001 | |
| Follow up group | Unvaccinated seronegative (reference) | 1.00 | 1.00 | ||||
| Unvaccinated seropositive | 0.02 | <01–.18 | <.001 | 0.15 | .08–.26 | <.001 | |
| Vaccinated once, previously seronegative | 0.33 | .21–.52 | <.001 | 0.36 | .26–.50 | <.001 | |
| Vaccinated twice, previously seronegative | No events | 0.10 | .02–.38 | <.001 | |||
| Vaccinated, previously seropositive | 0.07 | .01–0.51 | .009 | 0.04 | .01–.27 | .001 | |
| Ethnic group | White (reference) | 1.00 | 1.00 | ||||
| Asian | 1.90 | 1.47–2.46 | <.001 | 1.59 | 1.32–1.91 | <.001 | |
| Black | 1.09 | .62–1.91 | .78 | 1.25 | .88–1.78 | .21 | |
| Other | 1.31 | .87–1.97 | .20 | 1.23 | .93–1.62 | .16 | |
| Role | Other (reference) | 1.00 | 1.00 | ||||
| Junior doctor | 1.35 | .86–2.12 | .20 | 1.10 | .78–1.54 | .59 | |
| Senior doctor (consultant) | 0.50 | .24–1.05 | .07 | 0.60 | .38–.95 | .03 | |
| Healthcare assistant | 1.71 | 1.18–2.47 | .005 | 1.82 | 1.42–2.34 | <.001 | |
| Nurse | 1.50 | 1.11–2.03 | .009 | 1.49 | 1.21–1.83 | <.001 | |
| Physio-, occupational or speech/language therapist | 0.65 | .26–1.61 | .35 | 1.17 | .73–1.88 | .51 | |
| Porter, domestic staff | 1.05 | .48–2.29 | .91 | 1.37 | .84–2.22 | .20 | |
| Administrator | 0.99 | .64–1.52 | .96 | 1.18 | .89–1.57 | .25 |
Event counts, follow-up, and unadjusted IRRs are provided in Supplementary Table 2.
Abbreviations: CI, confidence interval; ICU, intensive care unit; PCR, polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.