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Multicenter Study
. 2025 Mar;60(3):e71022.
doi: 10.1002/ppul.71022.

Respiratory Syncytial Virus Burden in Premature Infants: The Role of Season With and Without RSV Immunoprophylaxis in a Multicenter Study

Keren Armoni Domany  1   2 , Avigdor Mandelberg  1   2 , Nitzan Burrack  3   4 , Inbal Golan-Tripto  4   5 , Kamal Masarweh  6   7 , Michal Gur  6   7 , Mika Rochman  2   8 , Moria Be'er  2   8 , Dario Prais  2   9 , Merav Mor  2   10 , Moran Weinberger Opek  11 , Elias Nasrallah  12   13 , Orli Megged  14 , Rachel Shatzman Steuerman  2   15   16 , Michal Stein  2   15 , Zohar Steinberg  7   17 , Shereen Shehadeh  7   18 , Aharona Glatman-Freedman  2   19 , Diana Tasher  1   2   20
Affiliations
Multicenter Study

Respiratory Syncytial Virus Burden in Premature Infants: The Role of Season With and Without RSV Immunoprophylaxis in a Multicenter Study

Keren Armoni Domany et al. Pediatr Pulmonol. 2025 Mar.

Abstract

Objective: To compare the Respiratory Syncytial Virus (RSV) hospitalization burden among 29-34 weeks gestational age (wGA) preterm infants between seasons with and without routine palivizumab prophylaxis, by utilizing the 2021 off-season RSV surge.

Methods: This multi-center retrospective study was conducted in 11 medical centers across Israel. We included infants > 1 year-old, with wGA data, hospitalized with RSV infection from November 2017-August 2021. National palivizumab compliance data were collected separately. We compared two periods: in-season (November-March) with routine palivizumab prophylaxis as the reference, and off-season (April-October) without prophylaxis as the primary risk factor. The primary outcome was the proportion of RSV hospitalizations in 29-34 wGA infants relative to total RSV admissions, calculated separately for each period. Secondary outcomes included clinical severity parameters.

Results: A total of 3296 infants were admitted during the RSV in-season, and 1044 during the off-season. National palivizumab compliance among eligible infants during the in-season study years was 91%-95%. The proportion of 29-34 wGA infants was significantly higher during the off-season compared to the in-season period (7% vs. 2.1%, p < 0.001). In a multivariable logistic regression model, the odds of hospitalization for 29-34 wGA preemies were 2.6 times higher during the off-season compared to the in-season (95% CI: 1.8-3.9, p < 0.001), independent of demographic covariates. Clinical severity was similar between the two periods.

Conclusions: Our results revealed a significantly higher proportion of 29-34 wGA infants hospitalized during seasons without palivizumab prophylaxis compared to seasons with palivizumab prophylaxis. These findings highlight the importance of including 29-34 wGA infants into future RSV immunoprophylaxis recommendations.

Keywords: COVID‐19; bronchiolitis; immunoprophylaxis; respiratory syncytial virus.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Distribution of Hospitalized RSV Patients < 1 year of age. Bars represent the monthly number of hospitalized patients. [Color figure can be viewed at wileyonlinelibrary.com]
See this image and copyright information in PMC

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