Table 4.
Adjusted incidence ratios for zoster in 9604 adults during risk periods for those with one, two, or three or more recorded household varicella exposures
| Varicella exposure and time period | No. of zoster events | Age, calendar time, and season adjusted incidence ratio* (95% CI) |
|---|---|---|
| Baseline† | 4114 | 1.00 |
| 1st exposure | ||
| 60 days pre-exposure | 429 | 2.90 (2.61 to 3.23) |
| Years post-exposure: | ||
| 0-<2 | 1149 | 0.67 (0.62 to 0.72) |
| 2-<5 | 1372 | 0.70 (0.64 to 0.76) |
| 5-<10 | 1431 | 0.69 (0.62 to 0.77) |
| 10-20 | 811 | 0.75 (0.64 to 0.87) |
| 2nd exposure | ||
| 60 days pre-exposure | 24 | 1.64 (1.09 to 2.48) |
| Years post-exposure: | ||
| 0-<2 | 53 | 0.60 (0.44 to 0.81) |
| 2-<5 | 63 | 0.73 (0.55 to 0.98) |
| 5-<10 | 50 | 0.68 (0.48 to 0.96) |
| 10-20 | 87 | 0.80 (0.59 to 1.07) |
| ≥3rd exposure | ||
| 60 days pre-exposure | <5‡ | 0.59 (0.08 to 4.23) |
| Years post-exposure: | ||
| 0-<2 | <5‡ | 0.34 (0.10 to 1.10) |
| 2-<5 | <5‡ | 0.39 (0.12 to 1.29) |
| 5-<10 | 7 | 1.16 (0.47 to 2.86) |
| 10-20 | 7 | 1.42 (0.52 to 3.85) |
*
Age defined by 40 quantiles of age at event (herpes zoster); calendar time defined as 1997-98, 1999-2000, 2001-02, 2003-04, 2005-06, 2007-08, 2009-10, 2011-12, 2013-14, 2015-16, 2017-18; and season defined as winter (December-February), spring (March-May), summer (June-August), and autumn (September-November).
†
All time from observation start to 60 days pre-exposure, and after the 20 years after exposure.
‡
Cell counts less than five have been suppressed to preserve anonymity.