Table 1.
Protection from repeat positive test >90 days after initial infection and repeat positive test results per 100,000 person-days exposure, June–December, 2020, Kentucky, USA.
| Population and age group | No history of infectiona |
History of infectionb |
No history of infection versus history of infection RR (95% CI) | Estimated protection from repeat positive (95% CI)c | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Number at risk | Number positive (%) | Person-days exposured | Infection ratee | Number at risk | Number positive (%) | Person-days exposured | Infection ratee | |||
| All (female and male) | ||||||||||
| 20–39 | 173,522 | 10,162 (5.9%) | 14,630,087 | 69.5 | 17,815 | 194 (1.1%) | 1,479,352 | 13.1 | 5.4 (4.7–6.2) |
81.4 (78.6–83.9) |
| 40–49 | 79,321 | 4,829 (6.1%) | 7,083,308 | 68.2 | 7,291 | 94 (1.3%) | 636,749 | 14.8 | 4.7 (3.9–5.8) |
78.8 (74.1–82.7) |
| 50–59 | 87,493 | 4,987 (5.7%) | 8,000,157 | 62.3 | 6,807 | 81 (1.2%) | 594,563 | 13.6 | 4.8 (3.9–6.0) |
79.1 (74.0–83.2) |
| 60–69 | 84,353 | 4,399 (5.2%) | 7,954,388 | 55.3 | 5,004 | 77 (1.5%) | 435,004 | 17.7 | 3.4 (2.7–4.2) |
70.5 (63.1–76.4) |
| 70–79 | 54,375 | 3,474 (6.4%) | 5,164,484 | 67.3 | 2,810 | 70 (2.5%) | 249,843 | 28.0 | 2.6 (2.0–3.2) |
61.0 (50.8–69.1) |
| 80+ | 29,457 | 3,991 (13.5%) | 2,716,514 | 146.9 | 1,920 | 77 (4.0%) | 179,230 | 43.0 | 3.4 (2.7–4.2) |
70.4 (63.1–76.3) |
| All (female and male) | ||||||||||
| 20+ | 508,521 | 31,842 (6.3%) | 45,548,938 | 69.9 | 41,647 | 593 (1.4%) | 3,574,741 | 16.6 | 4.4 (4.1–4.8) |
77.3 (75.4–79.0) |
| 20–59 | 340,336 | 19,978 (5.9%) | 29,713,552 | 67.2 | 31,913 | 369 (1.2%) | 2,710,664 | 13.6 | 5.1 (4.6–5.6) |
80.3 (78.2–82.2) |
| 60+ | 168,185 | 11,864 (7.1%) | 15,835,386 | 74.9 | 9,734 | 224 (2.3%) | 864,077 | 25.9 | 3.1 (2.7–3.5) |
67.4 (62.8–71.4) |
| Female | ||||||||||
| 20+ | 297,915 | 20,446 (6.9%) | 26,836,350 | 76.2 | 22,154 | 373 (1.7%) | 1,890,933 | 19.7 | 4.1 (3.7–4.5) |
75.5 (72.8–77.8) |
| 20–59 | 201,763 | 12,965 (6.4%) | 17,790,862 | 72.9 | 16,708 | 227 (1.4%) | 1,409,252 | 16.1 | 4.7 (4.2–5.4) |
78.9 (75.9–81.4) |
| 60+ | 96,152 | 7,481 (7.8%) | 9,045,488 | 82.7 | 5,446 | 146 (2.7%) | 481,681 | 30.3 | 2.9 (2.5–3.4) |
65.5 (59.5–70.7) |
| Male | ||||||||||
| 20+ | 210,606 | 11,396 (5.4%) | 18,712,588 | 60.9 | 19,493 | 220 (1.1%) | 1,683,808 | 13.1 | 4.8 (4.2–5.5) |
79.1 (76.2–81.7) |
| 20–59 | 138,573 | 7,013 (5.1%) | 11,922,690 | 58.8 | 15,205 | 142 (0.9%) | 1,301,412 | 10.9 | 5.4 (4.6–6.4) |
81.5 (78.2–84.4) |
| 60+ | 72,033 | 4,383 (6.1%) | 6,789,898 | 64.6 | 4,288 | 78 (1.8%) | 382,396 | 20.4 | 3.3 (2.7–4.2) |
70.1 (62.7–76.1) |
Abbreviations: RR, relative risk; CI, confidence interval; F, female; M, male; SARS-CoV-2, severe respiratory syndrome coronavirus-2
Individuals who had at least one negative test for SARS-CoV-2 and no subsequent positive result within 90 days during the time period March 6, 2020 through August 31, 2020
Individuals who had a positive PCR or antigen test for SARS-CoV-2 during the time period March 6, 2020 through August 31, 2020
Calculated as (1-(1/RR of no history of infection versus history of infection)) x 100 or (1-RR of history of infection versus no history of infection) x 100
For each individual, person-days of exposure began on day 91 after the referent initial positive or negative test and accumulated until a positive test result or until December 31, 2020, whichever came first
Rate of infection per 100,000 person-days of exposure