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. 2024 Jan 16;115(2):220–229. doi: 10.17269/s41997-023-00848-4

Table 2.

First episode of COVID-19, polymerase chain reaction (PCR) tests, and vaccine shots by infection wave: healthcare workers (HCW, N=2959) and community referents (CR, N=14,546)

Wave COVID-19 medical report Positive PCR Any PCR test Two or more vaccine shots
HCW CR All HCW CR All HCW CR All HCW CR All

1

(March–June 2020)

 N 457 1701 2158 7 12 19 973 1605 2578 0 0 0
% 15.4 11.7 12.3 0.2 0.1 0.1 32.9 11.0 14.7 0.0 0.0 0.0

2

(July 2020–February 2021)

 N 255 996 1251 104 370 474 1984 5768 7752 1471 510 1981
% 8.6 6.8 7.1 3.5 2.5 2.7 67.0 39.7 44.3 49.7 3.5 11.3

3

(March–June 2021)

 N 107 548 655 22 278 300 840 2688 3528 2675 6855 9530
% 3.6 3.8 3.7 0.7 1.9 1.7 28.4 18.5 20.2 90.4 47.1 54.4

4

(July–October 2021)

 N 28 222 250 44 275 319 986 2674 3660 2856 11,390 14,246
% 0.9 1.5 1.4 1.5 1.9 1.8 33.3 18.4 20.9 96.5 78.3 81.4

5

(November 2021–March 2022)

 N 94 364 458 442 785 1227 1353 2599 3952 2870 11,946 14,816
% 3.2 2.5 2.6 14.9 5.4 7.0 45.7 17.9 22.6 97.0 82.1 84.6
Wave Total PCR tests Proportion of PCR tests positive Vaccine shots
HCW CR All HCW CR All HCW CR

All

NA

1

(March–June 2020)

 Mean 0.39 0.12 0.17 0.01 0.01 0.01 NA* NA
SD 0.63 0.38 0.44 0.07 0.08 0.08 - - -

2

(July 2020–February 2021)

 Mean 1.80 0.76 0.94 0.03 0.04 0.04 1.07 0.08 0.25
SD 2.56 1.52 1.78 0.14 0.18 0.17 0.96 0.38 0.64

3

(March–June 2021)

 Mean 0.45 0.28 0.30 0.02 0.09 0.07 1.85 1.19 1.31
SD 0.91 0.88 0.89 0.11 0.27 0.24 0.48 0.84 0.83

4

(July–October 2021)

 Mean 0.46 0.26 0.29 0.04 0.09 0.08 2.00 1.66 1.72
SD 0.79 0.80 0.81 0.18 0.27 0.25 0.43 0.84 0.79

5

(November 2021–March 2022)

 Mean 0.70 0.24 0.32 0.24 0.26 0.25 2.79 2.15 2.26
SD 1.00 0.73 0.80 0.39 0.41 0.40 0.60 1.07 1.03

*not applicable, no vaccine available