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.

Background: Studies on post-COVID-19 condition (PCC) in adults have shown deterioration in pulmonary function tests (PFTs), mainly a diffusion limitation. Among pediatric population data are scarce. Aim: To characterize PFTs of children with PCC, including changes over time. Methods: A prospective longitudinal study of children with defined PCC and respiratory complaints referred to a designated multidisciplinary clinic from 11/2020 to 12/2022. Results: 184 children at a mean age of 12.4 years (SD 4.06) were included. A mild obstructive pattern was demonstrated in 19/170 (11%) at presentation, as indicated by spirometry and/or positive exercise challenge test and/or reversibility post bronchodilators- only 3 with a previous diagnosis of asthma. Lung volumes and diffusion were normal in all but one patient (1/134, 0.7%). [Exhaled nitric oxide](https://erj.ersjournals.com/content/21/1/43)  levels were elevated in 32/144 (22%). All 33 children who had repeated PFTs had normal or near-normal PFTs on following testing, including 7 (21.2%) who had mild obstructive PFTs at presentation. Multivariate analysis identified older age [OR 1.36 (95% CI:1.07-1.75)] and specific imaging findings [prominent bronchovascular markings (OR 43.28 (95% CI: 4.50-416.49)[ and hyperinflation ](OR 28.42, 95% CI: 2.18-370.84)] as significant predictors of an obstructive pattern on PFTs. Conclusion: In children with PCC and respiratory symptoms, the most common impairment was mild obstructive pattern; most of them without a history of asthma. Improvement was witnessed in long-term follow-up. As opposed to the adult population, no diffusion limitation was found. Empirical periodic inhaler therapy may be considered in children with factors associated with PFTs abnormalities.