Pertussis in Italy: how to protect the “unprotectable”?

Figures & data

Table 1. Characteristics of infants (<12 months old) hospitalized for pertussis in 2007–2018, in Italy

	N = 4262
Gender, n (%)
Male	2074 (48.7)
Female	2188 (51.3)
Age (days), mean ± SD	92.1 ± 63.6
Age classes, n (%)
<3 months	2604 (61.1)
3–4 months	723 (17.0)
5–10 months	841 (19.7)
>10 months	94 (2.2)
Nationality, n (%)
Italian	3891 (91.3)
Foreign	371 (8.7)
Geographical location, n (%)
North	1323 (31.0)
Center	935 (21.9)
South and islands	2004 (47.0)
Seasonality, n (%)
Winter	741 (17.4)
Spring	1211 (28.4)
Summer	1624 (38.1)
Autumn	686 (16.1)
Deaths, n (%)
No	4252 (99.8)
Yes	10 (0.2)
Diagnosis of pertussis, n (%)
Principal	3322 (77.9)
Secondary	940 (22.1)
ICD9CM codes, n (%)
033.0 Whooping cough due to Bordetella pertussis	1813 (42.5)
033.1 Whooping cough due to Bordetella parapertussis	131 (3.1)
033.8 Whooping cough due to other specified organism	103 (2.4)
033.9 Whooping cough, unspecified organism	2073 (48.6)
484.3 Whooping cough, unspecified species with pneumonia	142 (3.3)
Length of hospital stay (days), mean ± SD	7.5 ± 7.4

Figure 1. Yearly frequency distribution and hospitalization rates for pertussis admissions in Italian infants aged <12 months, 2007–2018. Trend test. Number of hospitalizations: β = 8.71, p = .104; hospitalization rates: β = 3.18, p = .009

Figure 2. A) Pertussis hospitalization rates for all etiologies stratified by age classes. Trend test. <3 months: β = 9.12, p = .002; 3–4 months: β = 0.96, p = .419; 5–10 months: β = 1.30, p = .053; >10 months: β = 0.52, p = .117. B) Bordetella pertussis-related hospitalization rates stratified by age classes. Trend test for B. pertussis hospitalization rates. <3 months: β = 18.11, p < .001; 3–4 months: β = 3.71, p = .002; 5–10 months: β = 1.54, p = .001; >10 months: β = 0.57, p = .011. dtp3 and dt_dtp3: diphtheria-tetanus-pertussis vaccines. Trend test for vaccination coverage (VC). VC(dtp3): β = −0.23, p=.003; VC(dt_dtp3): β=-0.27, p=.001