Volume 28, Number 10—October 2022
Research
SARS-CoV-2 Secondary Attack Rates in Vaccinated and Unvaccinated Household Contacts during Replacement of Delta with Omicron Variant, Spain
Table 3
Risk of infection among contacts relative to vaccination status in a study of SARS-CoV-2 secondary attack rates in vaccinated and unvaccinated household contacts during replacement of Delta with Omicron variant, Spain*
Variable | Delta-dominant period |
Omicron-dominant period |
RR§ (95% CI) | p value | |||
---|---|---|---|---|---|---|---|
Patients† | p value‡ | Patients† | p value‡ | ||||
Vaccination status, contacts | |||||||
Vaccinated | 50/101 (49.5) | 0.1 | 112/124 (90.3) | 0.3 | 6.48 (3.0–13.8) | <0.001 | |
Unvaccinated | 35/56 (62.5) | 28/29 (96.6) | 10.4 (1.2–82.5) | 0.03 | |||
Vaccinated, <20 wk | 23/62 (37.1) | 0.002 |
59/65 (90.8) | 0.8 |
9.16 (3.4–25.0) | <0.001 | |
Vaccinated, >20 wk |
27/39 (69.3) |
52/58 (89.7) |
2.91 (0.8–10.2) |
0.1 |
|||
Vaccination status, index | |||||||
Vaccinated | 67/112 (59.8) | 0.02 | 108/120 (90.0) | 0.2 | 3.99 (2.0–8.1) | <0.001 | |
Unvaccinated | 18/45 (40.0) | 32/33 (97.0) | 43.5 (5.1–369.9) | 0.001 |
*RR, relative risk †Values are no. infected/total no. (%) patients in each strata. ‡p values for differences between vaccinated and unvaccinated groups. §RR between Omicron vs. Delta variant, adjusted by age of contact.