Table 3.

Summary of Cox regression models to assess the association of clinicodemographic factors with breakthrough infection in individuals vaccinated with two or three doses of mRNA vaccine

Factor	HR	Upper CI	Lower CI	p-value
Agea	0.989	1.008	0.969	0.2562
Comorbiditiesb	0.865	1.346	0.556	0.5226
Infection (ref: no infection, at day 0)c	0.130	0.289	0.059	< 0.0001
Sex (ref: male)a	1.465	2.322	0.924	0.1044
Smokerd	0.768	1.261	0.468	0.2980
Time since last dose (days)e	1.001	1.004	0.997	0.6598
Time since last infection (days)c	1.003	1.006	1.001	0.0014
Vaccination with 3 doses (ref: 2 doses)f	1.546	7.720	0.309	0.5950

HR hazard ratio

^aNon-adjusted variable. N = 369

^bCovariates for adjustment included age, sex, and smoking. N = 368

^cCovariates for adjustment included age, comorbidities, chronic medication, sex, smoking, and vaccination with 3 doses (ref: 2 doses). An interaction term was included between infection and time since last infection. N = 277

^dCovariates for adjustment included age and sex. N = 368

^eCovariates for adjustment included vaccination with 3 doses (ref: 2 doses). N = 369

^fTime since dose 3 was included as an interaction. N = 369