Table 3.
Number of participants in high-risk groups of influenza, and mean annual rate of hospital contact per 1,000 children by risk-groups in children under 18 years of age in Norway, 2015–2017.
| Risk-group* | NorEPIS | Norway, 2015–2017 | |||
|---|---|---|---|---|---|
| Hospital | Influenza | Mean population | Estimated number | Mean annual | |
| contacts† | cases‡ | size (0–18 years) | of influenza cases | annual | |
| N = 3,010 (%) | N = 309 (%) | in riskgroups§ | treated in hospitals|| | rate | |
| Prematurity, gestational age <37 weeks | 326 (10.8) | 35 (11.3) | 63,374 | 123.3 (102.0–148.1) | 1.9 (1.6–2.3) |
| Trisomy 21 | 32 (1.1) | 1 (0.3) | 1,638 | 3.5 (2.9–4.2) | 2.1 (1.8–2.6) |
| Congenital heart disease | 174 (5.8) | 23 (7.4) | 18,096 | 81.0 (67.0–97.2) | 4.5 (3.7–5.4) |
| Pulmonary disease¶ | 46 (1.5) | 5 (1.6) | 2,363 | 17.6 (14.6–21.2) | 7.5 (6.2–9.0) |
| Bronchopulmonary dysplasia | 63 (2.1) | 5 (1.6) | 1,034 | 17.6 (14.6–21.2) | 17.0 (14.1–20.5) |
| Immunosuppression/deficiency | 32 (1.1) | 6 (1.9) | 1,888 | 21.1 (17.5–25.4) | 11.2 (9.2–13.4) |
| Cancer** | 21 (0.7) | 3 (1.0) | 21,14 | 10.6 (8.7–12.7) | 5.0 (4.1–6.0) |
| Asthma | 265 (8.8) | 48 (15.5) | 55,268 | 169.0 (139.8–203.0) | 3.1 (2.5–3.7) |
| Nevromuscular disease | 92 (3.1) | 17 (5.5) | 10,809 | 59.9 (49.5–71.9) | 5.5 (4.6–6.7) |
| Epilepsy | 14 (0.5) | 4 (1.3) | 10,690 | 14.0 (11.6–16.9) | 1.3 (1.1–1.6) |
| Any underlying condition‡ | 471 (15.7) | 65 (21.0) | 84,776 | 229.0 (189.4–275.0) | 2.7 (2.2–3.2) |
*ICD-10 codes used to identify risk groups are provided in supplementary data. †Total number of hospital contacts in the NorEPIS cohort.‡Number of influenza cases in the NorEPIS cohort. § Mean size of background population during the 3 study years. || Estimated mean annual number of influenza cases treated at Norwegian hospitals. ¶ Pulmonary disease not including asthma or bronchopulmonary dysplasia. **Cancer patients receiving active chemotherapeutic treatment. ††Diagnosed with any of Trisomy 21, congenital heart disease, pulmonary disease, bronchopulmonary dysplasia, immunosuppression, cancer, asthma, epilepsy.