Table 3

SARS-CoV-2 Secondary Attack Rates in Vaccinated and Unvaccinated Household Contacts during Replacement of Delta with Omicron Variant, Spain

Israel López-Muñoz, Ariadna Torrella, Olga Pérez-Quílez, Amaia Castillo-Zuza, Elisa Martró, Antoni E. Bordoy, Verónica Saludes, Ignacio Blanco, Laura Soldevila, Oriol Estrada, Lluís Valerio, Sílvia Roure, and Xavier Vallès

Author affiliations: North Metropolitan International Health Program, Catalan Institute of Health (PROSICS), Badalona, Spain (I. López-Muñoz, A. Torrella, O. Pérez-Quílez, A. Castillo-Zuza, L. Soldevila, L. Valerio, S. Roure, X. Vallès); Hospital Universitari Germans Trias i Pujol, Badalona (E. Martró, A.E. Bordoy, V. Saludes, I. Blanco, L. Soldevila, S. Roure); Center for Biomedical Research in Epidemiology and Public Health (CIBEREPS), Instituto de Salud Carlos III, Madrid, Spain (E. Martró, A.E. Bordoy, V. Saludes); Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, Badalona (E. Martró, A.E. Bordoy, V. Saludes, I. Blanco, O. Estrada, X. Vallès); Fundació Lluita contra la Sida i les Malalties Transmissibles, Badalona (L. Soldevila, S. Roure, X. Vallès)

Main Article

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
Variable	Patients†	p value‡	Patients†	p value‡	RR§ (95% CI)	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)	0.1	28/29 (96.6)	0.3	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)	0.002	52/58 (89.7)	0.8	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)	0.02	32/33 (97.0)	0.2	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.

Main Article

Page created: August 11, 2022

Page updated: September 20, 2022

Page reviewed: September 20, 2022

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