Risk of SARS-CoV-2 Infection and Hospitalisation in Immunocompromised Children: A Population-Based Cohort Study in Italy and Norway

Aim Immunocompromised children (IC) were presumed to be at higher risk of SARS-COV-2 infection and severe COVID-19, but population-based evidence is limited. We assessed infection risk, COVID-19 hospitalisation, and severe outcomes in IC compared with children with and without other high-risk conditions. Methods We conducted a retrospective population-based cohort study using electronic health registries from Italy and Norway, including children aged 1–14 years from February 2020–February 2022. Children were classified as IC, non-immunocompromised with high-risk conditions (non-IC), or reference children (RC). Adjusted models estimated infection hospitalisation risks. Results We included 29 520 children (IC = 201, non-IC = 5 144, RC = 24 175) in Italy and 851 517 (IC = 4 862, non-IC = 157 358, RC = 689 297) in Norway. Infection rates were similar across groups in both countries. Hospitalisations were rare in both datasets; however, in the Norwegian cohort, the aHR for hospitalisation was 5.29 (95% CI: 2.49–11.25) for IC vs. RC and 2.30 (95% CI: 1.10–4.82) for IC vs. non-IC. Zero and five severe cases occurred in Italy and Norway, respectively. Conclusions IC did not have an increased risk of infection but experienced higher hospitalisation rates despite a low incidence of severe disease. This pattern may reflect precautionary clinical management rather than increased disease severity.