Results of a regional immunoprophylaxis program for children at risk of a severe course of respiratory syncytial virus infection with palivizumab in the Republic of Bashkortostan

Background. Palivizumab has been successfully used in many countries worldwide to prevent respiratory syncytial infection in children at risk of severe infection. Despite the drug use experience in some regions of the Russian Federation, evidence on the outcomes of specific immunoprophylaxis in children from risk groups is scarce.

Aim. To assess the results of the regional immunoprophylaxis program for children at high risk of severe respiratory syncytial virus infection (RSVI) with palivizumab in the Republic of Bashkortostan.

Materials and methods. A single-center retrospective cohort study was conducted at the Catamnesis Cabinet of the Republican Clinical Perinatal Center, Ufa. A total of 516 preterm infants born before the full 35 weeks of gestation and who reached the age of 1 year of life between April 2020 and April 2022 were included in the study. Group 1 (palivizumab+) included 250 infants who received at least one immunization against RSVI at a dose of 15 mg/kg; Group 2 (palivizumab-) included 266 infants without immunization. In both groups, the percentage of children admitted to the clinic for acute respiratory infections and hospitalized for lower respiratory infections was determined.

Results. It was found that children born at a gestational age of 32 weeks had immunoprophylaxis more often than children born at a gestational age of 32–35 weeks (58.1% vs 37.2%; p<0.001); also, they more often received 3–5 injections of palivizumab (32.9% vs 17.9%; p=0.018). The proportion of children who were admitted to the clinic for ARI was lower among those immunized than among those not immunized: 63.6% vs 82.0% (p<0.001; relative risk – RR 0.77, 95% confidence interval – CI 0.69–0.86). Of children who received 1–2 injections of palivizumab, 70.2% sought medical care for acute respiratory infections versus 53.3% of children who received 3–5 injections (p<0.001; RR 1.51, 95% CI 1.15–1.98). Among the immunized infants, the percentage of children admitted to the hospital for bronchitis was significantly lower: 24.0% vs 31.6% (p=0.045; RR 0.74, 95% CI 0.55–0.99). The most significant effect of palivizumab was demonstrated in children born at the gestational age of 32 weeks or less, who received 3–5 injections of the drug.

Conclusion. The study demonstrated the effectiveness of the regional RSVI immunoprophylaxis program with palivizumab in children in the first year of life at risk for severe infection in the Republic of Bashkortostan.