Objective: To elucidate the impact of lack of Palivizumab administration during off-season RSV periods on the RSV-related hospitalization among 29-34 weeks of gestational age (wGA) preterm infants. We utilized the summer of 2021 off-season RSV surge during the COVID19 pandemic. Methods: This multi-center retrospective observational study was conducted in 11 medical centers across Israel. We included infants > 1 year-old hospitalized with RSV infection between November 2017-August 2021. Patients were categorized into an in-season admissions group (November-March) and off-season admissions group (April-October). The primary outcome was the proportion of RSV hospitalizations among 29-34wGA infants in relation to total RSV admissions during the same season. Secondary outcomes included clinical severity parameters. Results A total of 3,296 infants were admitted during the RSV season, and 1,044 during the off-season. The proportion of 29-34wGA preemies was significantly higher in the off-season group compared to the in-season group (7% vs 2.1%, p<0.001). In the off-season group, we observed a significantly higher proportion of Jewish individuals (80.1% vs. 59.2%, p=0.001) and higher socioeconomic status (55.1% vs. 45.1%, p<0.001) compared to the in-season group. In the multivariable logistic-regression model, off-season hospitalization odds for 29-34 wGA preemies were significantly higher (2.6-fold, 95% CI:1.8-3.9, p<0.001) compared to in-season, irrespective of demographic covariates. Similar clinical severity parameters was observed between the groups. Conclusions Our results revealed a significantly higher proportion of infants born at 29-34 wGA among those hospitalized during off-season periods compared to in-season periods. These findings highlight the importance of including 29-34 wGA infants into future RSV immunoprophylaxis recommendations.

Objective: This retrospective observational cohort study aimed to assess the real-life application of bronchial challenge test (BCT) in the management of preschool children presenting with atypical recurrent respiratory symptoms (ARRS). Methods: We included children, aged 0.5-6 years referred to a pediatric-pulmonology clinic, who underwent BCT using methacholine or adenosine between 2012-2018 due to ARRS including uncertain severity of airway hyperactivity. BCT was considered positive based on spirometry results and/or wheezing, desaturation, and tachypnea reactions. We collected data on demographics, BCT results, pre-BCT treatment, post-BCT treatment change and post-BCT symptoms control. The primary outcome measure was the change in treatment post-BCT (step-up or step-down). Secondary outcome included clinical improvement observed 3-6 months after BCT. Results: A total of 228 children (55% males) with a mean age of 4.2±0.6 years underwent BCT (52% adenosine-BCT, 48% methacholine-BCT). Children referred for methacholine were significantly younger compared to adenosine (3.6±1.2 vs. 4.2±1.2 years, P<0.01). Methacholine and adenosine BCTs were positive in 95% and 61%, respectively. Overall, changes in management were observed in 122(53.5%) children following BCT, with 83(36.4%) being stepped up and 37(17%) being stepped down. Significantly more children in the methacholine group were stepped up compared to the adenosine (46% vs 28%, p=0.004). During the follow-up assessment, we observed a clinical improvement in 119/162 (73.4%) of the children. Conclusion: This study demonstrates the importance of BCT in the management of preschool children presenting to pediatric pulmonary-units with ARRS. The change in treatment and subsequent clinical improvement observed, highlight the added-value of BCT in this populations.