Real Life Effectiveness of Nirsevimab in Preventing Bronchiolitis Associated with Respiratory Syncytial Virus in Infants
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Reviewed & Translated by Dat Tien Nguyen, B.A, ScM.
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Posted on August 28th, 2024
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Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections, such as bronchiolitis, in children. With its extended in vivo half-life and strong neutralizing ability, Nirsevimab was approved by the US Food and Drug Administration and the European Medicines Agency in early 2023 for use as a pre-exposure prophylaxis against RSV. A study, recently published in the New England Journal of Medicine, evaluated the real-world effectiveness of nirsevimab in preventing hospitalizations due to RSV-associated bronchiolitis in children.
The case-control study was conducted in France and included 1,035 infants with a median age of about 3 months. Among the participants, 690 infants were hospitalized with bronchiolitis and tested positive for respiratory syncytial virus (RSV) via PCR. These cases were matched with 345 other infants hospitalized for unrelated conditions, such as gastroenteritis, urinary tract infections, and colic, without any respiratory symptoms. Infants who had received other RSV pre-exposure prophylaxis, like palivizumab, or those born to mothers vaccinated against RSV, were excluded from the study. A review of medical records revealed that 8.7% of the children hospitalized due to RSV-associated bronchiolitis had been treated with nirsevimab, compared to a 28.1% usage rate in the control group. After adjusting for sex, gestational age at birth, birth weight, and risk factors for severe bronchiolitis, the study estimated nirsevimab's effectiveness in preventing hospitalization due to RSV-associated bronchiolitis at 83%. Its effectiveness in preventing admission to critical care and the need for ventilatory support was found to be 69.6% and 67.2%, respectively. The researchers noted that high rates of prior RSV infection and immunity in pregnant women post-COVID-19 pandemic might have reduced virus transmission, potentially influencing the results.
The case-control study was conducted in France and included 1,035 infants with a median age of about 3 months. Among the participants, 690 infants were hospitalized with bronchiolitis and tested positive for respiratory syncytial virus (RSV) via PCR. These cases were matched with 345 other infants hospitalized for unrelated conditions, such as gastroenteritis, urinary tract infections, and colic, without any respiratory symptoms. Infants who had received other RSV pre-exposure prophylaxis, like palivizumab, or those born to mothers vaccinated against RSV, were excluded from the study. A review of medical records revealed that 8.7% of the children hospitalized due to RSV-associated bronchiolitis had been treated with nirsevimab, compared to a 28.1% usage rate in the control group. After adjusting for sex, gestational age at birth, birth weight, and risk factors for severe bronchiolitis, the study estimated nirsevimab's effectiveness in preventing hospitalization due to RSV-associated bronchiolitis at 83%. Its effectiveness in preventing admission to critical care and the need for ventilatory support was found to be 69.6% and 67.2%, respectively. The researchers noted that high rates of prior RSV infection and immunity in pregnant women post-COVID-19 pandemic might have reduced virus transmission, potentially influencing the results.