Volume 29, Number 3—March 2023
Dispatch
Risk Factors for Reinfection with SARS-CoV-2 Omicron Variant among Previously Infected Frontline Workers
, James Hollister, Cynthia J. Porter, Sana M. Khan, Leora R. Feldstein, Allison L. Naleway, Manjusha Gaglani, Alberto J. Caban-Martinez, Harmony L. Tyner, Ashley A. Lowe, Lauren E.W. Olsho, Jennifer Meece, Sarang K. Yoon, Josephine Mak, Jennifer L. Kuntz, Natasha Schaefer Solle, Karley Respet, Zoe Baccam, Meredith G. Wesley, Matthew S. Thiese, Young M. Yoo, Marilyn J. Odean, Flavia N. Miiro, Steve L. Pickett, Andrew L. Phillips, Lauren Grant, James K. Romine, Meghan K. Herring, Kurt T. Hegmann, Julie Mayo Lamberte, Brian Sokol, Krystal S. Jovel, Mark G. Thompson, Patrick Rivers, Tamara Pilishvili, Karen Lutrick, Jefferey L. Burgess, Claire M. Midgley, and Ashley L. Fowlkes
Table
Composition of study sample at risk for reinfection with SARS-CoV-2 during Omicron predominance, United States, December 2021‒April 2022*
| Characteristic | No. participants, n = 1,530† | No. reinfected, n = 318 | No. person-days at risk, n = 124,665 | Reinfection incidence/1,000 days at risk (95% CI) | Unadjusted HR (95% CI)‡ | Adjusted HR (95% CI)§ |
|---|---|---|---|---|---|---|
| Site, no. (%) | ||||||
| Tucson, AZ | 579 (37.8) | 109 | 47,933 | 2.27 (1.85‒2.70) | Referent | Referent |
| Phoenix, AZ | 211 (13.8) | 40 | 17,054 | 2.35 (1.62‒3.07) | 1.03 (0.72‒1.49) | 0.99 (0.66‒1.48) |
| Other areas in AZ | 123 (8.0) | 21 | 10,389 | 2.02 (1.16‒2.89) | 0.88 (0.56‒1.42) | 0.75 (0.46‒1.35) |
| Temple, TX | 93 (6.1) | 20 | 8,003 | 2.50 (1.40‒3.59) | 1.15 (0.71‒1.85) | 1.12 (0.68‒1.82) |
| Portland, OR | 59 (3.9) | 9 | 4,851 | 1.86 (0.64‒3.07) | 0.84 (0.42‒1.65) | 0.99 (0.48‒2.01) |
| Miami, FL | 151 (9.9) | 43 | 11,834 | 3.63 (2.55‒4.72) | 1.66 (1.17‒2.37) | 1.28 (0.86‒1.91) |
| Duluth, MN | 135 (8.8) | 24 | 11,271 | 2.13 (1.28‒2.98) | 0.92 (0.59‒1.43) | 1.08 (0.67‒1.74) |
| Salt Lake City, UT |
179 (11.7) |
52 |
13,330 |
3.90 (2.84‒4.96) |
1.65 (1.19‒2.30) |
1.61 (1.09‒ 2.37) |
| Age category, y, no. (%) | ||||||
| 18–34 | 360 (23.5) | 83 | 28,112 | 2.95 (2.32‒3.59) | Referent | Referent |
| 35–49 | 662 (43.3) | 135 | 54,065 | 2.50 (2.08‒2.92) | 0.86 (0.66‒1.13) | 0.88 (0.65‒1.20) |
| 50–77 |
508 (33.2) |
100 |
42,488 |
2.35 (1.89‒2.81) |
0.82 (0.61‒1.10) |
0.89 (0.63‒1.27) |
| Sex, no. (%) | ||||||
| M | 605 (39.5) | 144 | 47,929 | 3.00 (2.51‒3.50) | Referent | Referent |
| F |
925 (60.5) |
174 |
76,736 |
2.27 (1.93‒2.60) |
0.76 (0.61‒0.95) |
0.95 (0.72‒1.25) |
| Race/ethnicity, no. (%)¶# | ||||||
| Non-Hispanic/White | 1,023 (66.9) | 197 | 84,350 | 2.34 (2.01‒2.66) | Referent | Referent |
| Non-Hispanic/Black | 44 (2.9) | 15 | 3,058 | 4.91 (2.42‒7.39) | 2.02 (1.19‒3.41) | 2.14 (1.17‒3.92) |
| Non-Hispanic/Asian | 30 (2.0) | 5 | 2,636 | 1.90 (0.23‒3.56) | 0.81 (0.33‒1.96) | 1.02 (0.43‒2.43) |
| Hispanic | 375 (24.9) | 88 | 29,837 | 2.95 (2.33‒3.57) | 1.26 (0.98‒1.62) | 1.30 (0.98‒1.72) |
| Other |
18 (1.2) |
3 |
1,605 |
1.87 (0.00‒3.98) |
0.81 (0.26‒2.56) |
0.56 (0.18‒1.78) |
| Comorbid conditions, no. (%)#** | ||||||
| 0 | 970 (63.4) | 206 | 78,492 | 2.62 (2.27‒2.98) | Referent | Referent |
| >1 |
489 (32.0) |
106 |
39,704 |
2.67 (2.16‒3.18) |
1.02 (0.80‒1.29) |
1.17 (0.90‒1.53) |
| Occupation, no. (%)†† | ||||||
| Heathcare personnel | 650 (42.5) | 126 | 53,745 | 2.34 (1.94‒2.75) | Referent | Referent |
| First responder | 400 (26.1) | 111 | 30,557 | 3.63 (2.96‒4.31) | 1.52 (1.18‒1.96) | 1.13 (0.78‒1.63) |
| Other essential worker |
480 (31.4) |
81 |
40,363 |
2.01 (1.57‒2.44) |
0.86 (0.65‒1.13) |
0.82 (0.60‒1.13) |
| Time-varying vaccination status, no.‡‡ | ||||||
| 0 doses | 441 | 125 | 32,879 | 3.80 (3.14‒4.47) | Referent | Referent |
| 1 dose | 34 | 5 | 2,605 | 1.92 (0.24‒3.60) | 0.56 (0.22‒1.40) | 0.56 (0.22‒1.42) |
| 2 doses | 646 | 107 | 48,039 | 2.23 (1.81‒2.65) | 0.58 (0.45‒0.75) | 0.57 (0.43‒0.75) |
| 3 doses |
513 |
81 |
42,726 |
1.90 (1.48‒2.31) |
0.55 (0.41‒0.72) |
0.54 (0.39‒0.75) |
| Mask use in community, no. (%)#§§ | ||||||
| Above mean (47%) | 766 (50.1) | 126 | 64,630 | 1.95 (1.61‒2.29) | Referent | Referent |
| Below mean |
735 (48.0) |
189 |
57,595 |
3.28 (2.81‒3.75) |
1.64 (1.31‒2.06) |
1.39 (1.07‒1.82) |
| Weekly work hours, no. (%)# | ||||||
| Below mean (30 hours) | 781 (51.0) | 154 | 64,077 | 2.40 (2.02‒2.78) | Referent | Referent |
| Above mean |
741 (48.5) |
164 |
59,901 |
2.74 (2.32‒3.16) |
1.14 (0.91‒1.41) |
1.09 (0.87‒1.37) |
| Time elapsed since first infection, y, no. (%) | ||||||
| <1 | 781 (51.0) | 133 | 65,239 | 2.04 (1.69‒2.39) | Referent | Referent |
| >1 | 749 (49.0) | 185 | 59,426 | 3.13 (2.66‒3.56) | 1.53 (1.23‒1.91) | 1.63 (1.28‒2.07) |
*HR, hazard ratio. †Column percentage reported. ‡Each covariate listed was entered into a Cox proportional hazard model as a single predictor to generate unadjusted hazard ratios §All covariates were entered into a fully adjusted model. ¶Other includes American Indian or Alaska Native, Asian/Pacific Islander, or multiracial. #Missing values for this variable but <5% of study sample; persons who had missing values were excluded from hazard ratio analyses. **Includes asthma, other chronic lung disease, cancer, diabetes, heart disease or condition, hypertension, immunosuppression, kidney disease, liver disease, neurologic disease or disorder, autoimmune disease, or other medical problem requiring clinical care for >6 months. ††Includes inpatient, ambulatory, and institutional healthcare personnel; First responders include nonfire emergency medical service workers, fire services, law enforcement and corrections personnel; other essential workers include persons who work in the hospitality, retail, food service, education, government, or grocery sectors and persons who work in essential infrastructure and operations. ‡‡Vaccination status was allowed to vary over the time period at risk by using the Andersen–Gill extension methods; column percentages are not provided because they do not add up to 100%. §§Refers to the reported percentage of time masks were worn while in public but not at work in the past 7 days averaged across the study period.