Introduction: Premature infants are at increased risk of developing chronic respiratory diseases, predisposing them to severe infections, such as those caused by respiratory syncytial virus (RSV). Palivizumab reduces the severity of RSV infections in high-risk children; however, its relationship with asthma development in premature infants remains unclear. Objective: This systematic review with meta-analysis aimed to review the literature and assess whether prophylaxis with palivizumab protects premature infants without congenital heart disease from developing asthma. Results: In total, 14 studies met the inclusion criteria, assessing 1,364,238 children; of these, 9,232 received palivizumab. No significant difference in the chance of developing asthma between the groups (odds ratio (OR) of 0.84, 95% CI [0.62 to 1.13], p = 0.1968). Heterogeneity between studies was I 2 = 35.6%. Subgroup analysis for children with a family history of atopy showed no significant reduction in asthma risk (OR 0.78, 95% CI: 0.40–1.55, p = 0.3390). Sensitivity analysis confirmed result robustness. IgE levels were similar between the groups (standardized mean difference [SMD] -0.03 [95% CI: -0.30; 0.23], p = 0.8088). Children who received palivizumab were diagnosed younger (SMD -0.24 [95% CI: -0.38; -0.09], p = 0.0014), with lower gestational age (MD -0.75 [95% CI: -1.61; 0.12], p = 0.0915). Conclusions: Palivizumab prophylaxis does not reduce asthma risk in premature children without congenital heart disease. Its primary benefit lies in preventing severe RSV infections, with no direct impact on asthma developing.

Background: Vitamin D may contribute to the balance in between regulatory and suppressive functions of T cells to modulate the inflammatory process in asthma. Objective: To assess serum vitamin D levels and their relationship with asthma control, asthma severity and its anti-inflammatory effect in children. Methods: This systematic review was based on articles published between 2009 and August 2022. Children under 18 years old with asthma were included. Results: The initial database search identified 2,015 manuscripts. Through screening identified only 25 eligible articles, but only eight studies met criteria for inclusion in the meta-analysis. The analysis revealed that in six studies involving 588 participants, mean 25-hydroxyvitamin D levels were lower in children with uncontrolled asthma compared to those with controlled asthma, with a mean difference of -5.07 (-8.57, -1.57) and a high rate of heterogeneity I 2 = 89%. In five studies comprising 362 patients, the relationship between vitamin D and asthma severity was assessed. Lower levels of vitamin D were associated with a higher risk of severe asthma in children, with a mean difference of -6.00 (-8.09, -3.90) and substantial heterogeneity (90%, p<0.00001). In most patients, no significant correlation was found between vitamin D and lung function. Furthermore, serum vitamin D showed an association with interleukins and with regulatory T lymphocytes. Conclusion: Vitamin D plays a critical role in reducing asthma attacks. However, more randomized studies are necessary for a thorough evaluation and definitive recommendation for vitamin D supplementation.