Volume 30, Number 7—July 2024
Dispatch
Vaccine Effectiveness against SARS-CoV-2 among Household Contacts during Omicron BA.2–Dominant Period, Japan
Tsuyoshi Ogata
, Hideo Tanaka, Akemi Kon, Noriko Sakaibori, and Emiko Tanaka
, Hideo Tanaka, Akemi Kon, Noriko Sakaibori, and Emiko Tanaka
Table 1
Attack rates among household contacts of index patients with SARS-CoV-2 Omicron BA.2 infection in study of vaccine effectiveness against SARS-CoV-2 among household contacts during Omicron BA.2–dominant period, Japan*
| Variables | No. household contacts, n = 952 | Infected contacts, n = 395 | Contact attack rate, % | Risk ratio (95% CI)† |
|---|---|---|---|---|
| Household contacts | ||||
| No. vaccination doses | ||||
| 0–1 | 399 | 198 | 49.6 | Referent |
| 2 | 246 | 102 | 41.5 | 0.84 (0.70–0.999) |
| 3 | 307 | 95 | 30.9 | 0.62 (0.51–0.76) |
| Recent vaccination | ||||
| N | 637 | 293 | 46.0 | Referent |
| Y |
315 |
102 |
32.4 |
0.70 (0.59–0.84) |
| Index patients | ||||
| No. vaccination doses | ||||
| 0–1 | 515 | 238 | 46.2 | Referent |
| 2 | 301 | 112 | 37.2 | 0.81 (0.68–0.96) |
| 3 | 136 | 45 | 33.1 | 0.72 (0.55–0.93) |
| Recent vaccination‡ | ||||
| N | 802 | 343 | 42.8 | Referent |
| Y | 150 | 52 | 34.7 | 0.81 (0.64–1.01) |
*Attack rates are stratified by vaccination doses or recent vaccination for household contacts or index patients. †Monovariate analyses. ‡Recent vaccination indicates last vaccine dose <3 months.
Page created: May 10, 2024
Page updated: June 22, 2024
Page reviewed: June 22, 2024
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