Nirsevimab found Effective in Preventing RSV-Associated Hospitalizations Among Infants in new research
In a
significant development in pediatric healthcare, nirsevimab, a long-acting
monoclonal antibody, has demonstrated robust real-world effectiveness in
protecting infants against respiratory syncytial virus (RSV)-associated
hospitalizations, according to an analysis by the New Vaccine Surveillance
Network during the period of October 1, 2023, to February 29, 2024.
The
report was published in CDC Morbidity and Mortality Weekly Report.
RSV is a
major cause of infant hospitalization in the U.S. Nirsevimab, a long-acting
antibody, is recommended by CDC for infants and at-risk children. Clinical
trials show high efficacy. This analysis provides the first U.S. estimate of
post-introduction nirsevimab effectiveness in infants’ first RSV season.
The
CDC’s Advisory Committee on Immunization Practices had earlier recommended
nirsevimab for infants under the age of 8 months and for children aged 8–19
months at an increased risk for severe RSV disease. This groundbreaking
antibody, known for its extended duration of action, emerged from phase 3
clinical trials with an 81% efficacy against RSV-associated lower respiratory
tract infections leading to hospitalization within 150 days after receipt.
In the
real-world setting, the New Vaccine Surveillance Network’s analysis focused on
699 infants hospitalized with acute respiratory illness during the specified
period. Among them, 8% (59 infants) had received nirsevimab at least 7 days
before the onset of symptoms.
Findings:
-
The
findings revealed an impressive 90% effectiveness of nirsevimab against
RSV-associated hospitalizations (95% CI = 75%–96%). -
Notably,
the median time from receipt to symptom onset was 45 days (IQR = 19–76 days).
Despite
the limited number of infants in the analysis who received nirsevimab and the
restricted interval data, the early estimate strongly supports the current
recommendation for nirsevimab’s use in preventing severe RSV disease in
infants.
The data
underscore the importance of timely intervention with nirsevimab, either
through maternal RSV vaccination or direct administration to infants.
It is
essential to note that the number of infants in the analysis who received
nirsevimab was relatively low, making it impractical to stratify the data by
the duration from receipt. However, the analysis acknowledges that nirsevimab
effectiveness is anticipated to decline with increasing time after receipt due
to antibody decay. Continued monitoring and further research will be crucial to
refining recommendations and understanding the long-term efficacy of nirsevimab
in preventing RSV-associated hospitalizations.
This
breakthrough in pediatric healthcare offers a promising avenue for safeguarding
infants against the leading cause of hospitalization in the United States. As
the medical community awaits additional data and comprehensive assessments, the
current findings affirm the potential of nirsevimab to reshape the landscape of
RSV prevention, offering hope for a healthier start in life for countless
infants.
Further reading: Moline HL, Tannis A, Toepfer AP, et al. Early Estimate of Nirsevimab Effectiveness for Prevention of Respiratory Syncytial Virus–Associated Hospitalization Among Infants Entering Their First Respiratory Syncytial Virus Season — New Vaccine Surveillance Network, October 2023–February 2024. MMWR Morb Mortal Wkly Rep 2024;73:209–214. DOI: http://dx.doi.org/10.15585/mmwr.mm7309a4
