Pediatric respiratory syncytial virus rehospitalization rate - a retrospective observational study from Switzerland

Abstract

Background: Long-acting monoclonal antibodies against Respiratory Syncytial Virus (RSV) have recently become available for prevention of severe disease including RSV hospitalization in children below two years of age. Data on the risk of rehospitalization among children, who had suffered from severe first RSV episode, remain important to inform the need for secondary prevention using a (additonal) dose of such an antibody. We studied the risk of RSV rehospitalization in a large cohort of patients with a particular focus on same-season rehospitalizations.

Methods: Retrospective single-center study of all RSV rehospitalizations occurring in 13 RSV seasons between 2009 and 2023 based on an ongoing RSV surveillance program. We calculated the overall and same-season rates of rehospitalizations for patients of any age and for the first 5 years of life, respectively, and provide a clinical description of of rehospitalization cases.

Results: In a cohort of 3'143 patients having had a primary RSV hospitalization, the overall risk of rehospitalization (69 cases) and same-season risk of rehospitalization (2 cases) for a second RSV infection were 2.2% (95% confidence interval (CI), 1.73-2.79) and 0.06% (95% CI 0.02-0.23), respectively. The figures for the RSV rehospitalization rates from birth until age 5 years of age were 2.3% (95% CI 1.76-3.07) for all rehospitalizations and 0.04% (95% CI 0.01-0.25) for same-season rehospitalizations. The median length of stay (LoS) of rehospitalizations (4.0 days, interquartile range (IQR) 3.0-6.0) was significantly shorter than the LoS of first hospitalizations (6.0 days, IQR 4.0-9.0, p < 0.0001). Children with a pre-existing condition (68%) and those born prematurely (40%) predominated among rehospitalized patients.

Conclusion: Same-season RSV rehospitalizations were exquisitely rare. Routine administration of a dose of a monoclonal antibody for protection against a same-season rehospitalization does not appear to be generally warranted. The majority of patients with subsequent season readmission would be covered by the current recommendations in Switzerland as they had pre-existing conditions making them eligible for second-season RSV prophylaxis.

Keywords: Nirsevimab; Prophylaxis; RSV; Readmission; Rehospitalization; Respiratory syncytial virus; Vaccine.

Fig. 1

Time sequence of annual RSV hospitalization frequencies in each epidemiological year from 2009 to 2023. In panel A, the gray bars indicate the total number of RSV hospitalizations per year, the blue bars denote the number of rehospitalizations in each year. Panel B shows rehospitalizations only

Fig. 2

Intervals in years between the first and the second RSV hospitalization in relation to the calendar month, in which the first hospitalization occurred. Each dot identifies one patient. The red dots identify the two cases with same-season rehospitalization. The dotted lane marks the minimum interval found among the remainder of patients

Fig. 3

Intervals (in years on the x-axis) between each RSV hospitalization are shown for each of the 69 patients with RSV rehospitalization(s) included in the study. Each dot denotes the patient age at an RSV hospitalization. Open circles identify ICU admissions. On the y-axis, patients are sorted from bottom to top according to their chronological age in months at the time of the first admission. Blue dots and lines identify patients with a severe pre-existing condition (pulmonary, cardiovascular, neuromuscular)