Table 1.

Characteristics of participants eligible in the Madrid region for the nirsevimab effectiveness study at the end of fifth month of follow-up.

Eligible participants for the study of nirsevimab effectiveness (N = 37,067)
	Inmunized against RSV (at the end of follow-up)		Non-immunized (at the end of follow-up)		Total number	p value
	Number	Frequency (%)	Number	Frequency (%)
Immune status at the end of follow-up
Total	29,684	80.08	7,383	19.92	37,067
Age in months: Median (IQR)
Start follow up	0.98 (3.38)		2.85 (3.51)		1.44 (3.67)	<0.001a
Final follow-up	5.90 (4.39)		7.61 (3.70)		6.26 (4.46)	<0.001a
Gestation weeks
23–27 weeks	66	0.22	18	0.24	84	0.0001b
28–33 weeks	477	1.61	74	1.00	551
34–36 weeks	1,677	5.65	371	5.03	2,048
37–41 weeks	27,159	91.49	6,784	91.89	33,943
42 or more weeks	24	0.08	21	0.28	45
NA	281	0.95	115	1.56	396
Type of birth
Single birth	28,754	96.87	7,239	98.05	35,993	<0.001c
Multiple birth	930	3.13	144	1.95	1,074
Sex
Female	14,290	48.14	3,641	49.32	17,931	<0.001d
Male	15,386	51.83	3,731	50.54	19,117
NA	8	0.03	11	0.15	19
Comorbidity
Undetected	27,347	92.13	6,925	93.80	34,272	<0.001c
Detected comorbidity	2,337	7.87	458	6.20	2,795
Comorbidity groups
Prematurity (< 35 weeks)	1,820	74.53	330	68.04	2,150	<0.001d
Lung pathology	204	8.35	55	11.34	259	0.594d
Cardiac pathology	280	11.47	70	14.43	350	0.969d
Immunodepression	52	2.13	12	2.47	64	0.815d
Metabolism disorders	53	2.17	10	2.06	63	0.421d
Neurological pathology	31	1.27	8	1.65	39	0.929d
Palliative care	2	0.08	0	0.00	2	0.481d
Average personal net income of the census section of residence (2021 data). Percentiles
Up to 10th (lower)	2,219	7.48	1,210	16.39	3,429	<0.001b
11th to 30th	4,944	16.66	1,909	25.86	6,853
31th to 50th	5,375	18.11	1,464	19.83	6,839
51th to 70th	5,845	19.69	983	13.31	6,828
71th to 90th	6,116	20.60	730	9.89	6,846
91th to 100th (higher)	3,082	10.38	336	4.55	3,418
NA	2,103	7.08	751	10.17	2,854
Cumulative incidence of suspected RSV in children aged 0 to 4 years by census section of residence. Percentiles
Up to 10th (lower)	2,778	9.36	603	8.17	3,381
11th to 30th	5,635	18.98	1,253	16.97	6,888
31th to 50th	5,537	18.65	1,263	17.11	6,800	0.5273b
51th to 70th	5,405	18.21	1,302	17.64	6,707	<0.001d
71th to 90th	5,553	18.71	1,447	19.60	7,000
91th to 100th (higher)	2,674	9.01	764	10.35	3,438
NA	2,102	7.08	751	10.17	2,853

^aWilcoxon rank-sum test.

^bCochran-Armitage test for trend across ordered groups.

^cTwo-sample test of proportions.

^dChi square test, table 2 × 2 or table r x 2. r = 1, 2, ..., n (number of rows).

NA, not available.