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. 2022 Apr 6;3(5):325–334.e4. doi: 10.1016/j.medj.2022.03.010

Table 2.

Positivity rates for Omicron and Delta among PCR tests performed between December 12 and 26, 2021. Rates shown in parentheses as means with 95% confidence intervals.

Variant All (vaccinated & unvaccinated, n = 33,416) 0 dose: unvaccinated (n = 17914) Vaccinated, 1 dose (n = 1,405) Vaccinated, 2 doses ≥5 months before test (n = 1,186) Vaccinated, 2 doses <5 months before test (n = 10,322) Vaccinated, 3 doses (n = 2,589)
Delta (Ct ≤ 30) 1,374 (0.041: 0.039, 0.043) 954 (0.053: 0.05, 0.057) 57 (0.041: 0.03, 0.051) 32 (0.027: 0.018, 0.036) 306 (0.03: 0.026, 0.033) 25 (0.01: 0.006, 0.013)
Omicron (Ct ≤ 30) 1,387 (0.042: 0.039, 0.044) 793 (0.044: 0.041, 0.047) 52 (0.037: 0.027, 0.047) 58 (0.049: 0.037, 0.061) 433 (0.042: 0.038, 0.046) 51 (0.02: 0.014, 0.025)
Negative or Ct > 30 30,655 (0.917: 0.914, 0.92) 16,167 (0.902: 0.898, 0.907) 1,296 (0.922: 0.908, 0.936) 1,096 (0.924: 0.909, 0.939) 9,583 (0.928: 0.923, 0.933) 2,513 (0.971: 0.964, 0.977)
Combined (Delta and Omicron) 2,761 (0.083: 0.08, 0.086) 1747 (0.098: 0.093, 0.102) 109 (0.078: 0.064, 0.092) 90 (0.076: 0.061, 0.091) 739 (0.072: 0.067, 0.077) 76 (0.029: 0.023, 0.036)