Table 3.
Incidence ratios for zoster in 9604 adults during risk periods after household exposure to a child with varicella, by other factors
| Time period | No. of zoster events | Age, calendar time, and season adjusted incidence ratio* (95% CI) | P value for interaction† |
|---|---|---|---|
| Sex | |||
| Men: | |||
| Baseline‡ | 1354 | 1.00 | P<0.001 |
| 60 days pre-exposure | 188 | 3.58 (3.05 to 4.20) | |
| Years post-exposure: | |||
| 0-<2 | 336 | 0.55 (0.48 to 0.62) | |
| 2-<5 | 417 | 0.57 (0.50 to 0.65) | |
| 5-<10 | 464 | 0.57 (0.49 to 0.67) | |
| 10-20 | 261 | 0.59 (0.48 to 0.74) | |
| Women: | |||
| Baseline‡ | 2762 | 1.00 | |
| 60 days pre-exposure | 245 | 2.49 (2.17 to 2.85) | |
| Years post-exposure: | |||
| 0-<2 | 841 | 0.74 (0.68 to 0.81) | |
| 2-<5 | 1015 | 0.76 (0.69 to 0.84) | |
| 5-<10 | 1082 | 0.76 (0.67 to 0.86) | |
| 10-20 | 639 | 0.82 (0.68 to 0.98) | |
| Age at household exposure to varicella (years) | |||
| 18-49: | |||
| Baseline‡ | 2834 | 1.00 | P=0.65 |
| 60 days pre-exposure | 350 | 2.90 (2.58 to 3.26) | |
| Years post-exposure: | |||
| 0-<2 | 924 | 0.66 (0.61 to 0.72) | |
| 2-<5 | 1133 | 0.68 (0.62 to 0.75) | |
| 5-<10 | 1288 | 0.69 (0.60 to 0.78) | |
| 10-20 | 808 | 0.75 (0.63 to 0.90) | |
| ≥50: | |||
| Baseline‡ | 1282 | 1.00 | |
| 60 days pre-exposure | 83 | 2.72 (2.16 to 3.42) | |
| Years post-exposure: | |||
| 0-<2 | 253 | 0.72 (0.61 to 0.83) | |
| 2-<5 | 299 | 0.74 (0.63 to 0.87) | |
| 5-<10 | 258 | 0.70 (0.56 to 0.86) | |
| 10-20 | 92 | 0.67 (0.48 to 0.93) | |
| Immunosuppression status at exposure to varicella | |||
| Immunocompetent: | |||
| Baseline‡ | 4056 | 1.00 | P=0.53 |
| 60 days pre-exposure | 424 | 2.84 (2.55 to 3.16) | |
| Years post-exposure: | |||
| 0-<2 | 1162 | 0.67 (0.62 to 0.73) | |
| 2-<5 | 1413 | 0.69 (0.63 to 0.75) | |
| 5-<10 | 1537 | 0.69 (0.61 to 0.77) | |
| 10-20 | 894 | 0.74 (0.62 to 0.87) | |
| Immune suppressed: | |||
| Baseline‡ | 60 | 1.00 | |
| 60 days pre-exposure | 9 | 4.74 (2.30 to 9.79) | |
| Years post-exposure: | |||
| 0-<2 | 15 | 0.74 (0.41 to 1.35) | |
| 2-<5 | 19 | 0.95 (0.53 to 1.71) | |
| 5-<10 | 9 | 0.52 (0.23 to 1.18) | |
| 10-20 | 6 | 0.94 (0.33 to 2.68) | |
*
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).
†
Calculated using likelihood ratio test.
‡
All time from observation start to 60 days pre-exposure, and after the 20 years after exposure.