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An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
Estimated Effectiveness of Nirsevimab Against Respiratory Syncytial Virus
Hanmeng Xu1, Camila Aparicio2, Aanchal Wats2
1Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut.
Insights
Nirsevimab significantly protects infants from respiratory syncytial virus (RSV) infections, including severe cases. This real-world evidence supports nirsevimab
Area of Science:
- Pediatric Infectious Diseases
- Immunology
- Public Health
Background:
- Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections (LRTI) in infants.
- Nirsevimab, a long-acting monoclonal antibody, has shown promise in clinical trials for preventing RSV-associated LRTI.
- Postlicensure studies are crucial to validate nirsevimab's effectiveness in real-world clinical settings.
Purpose of the Study:
- To evaluate the real-world effectiveness of nirsevimab in preventing medically attended RSV infections among infants.
- To analyze how nirsevimab's effectiveness varies based on disease severity, dosage, and time elapsed since immunization.
- To assess broader impacts on all-cause LRTI and related hospitalizations.
Main Methods:
- A test-negative case-control study design was employed.
- Data were sourced from inpatient, outpatient, and emergency departments within the Yale New Haven Health System.
- Infants tested for RSV via PCR between October 2023 and May 2024 were analyzed, with RSV-positive infants as cases and RSV-negative infants as controls.
Main Results:
- Nirsevimab demonstrated an adjusted effectiveness of 68.4% against medically attended RSV infections.
- Effectiveness was particularly high against severe RSV disease (84.6%) and RSV-related hospitalizations (80.5%).
- While effectiveness waned over time, it remained significant up to 14 weeks post-immunization; effectiveness against all-cause LRTI was observed during peak RSV season.
Conclusions:
- Nirsevimab provides substantial real-world protection against RSV-associated respiratory infections in infants.
- These findings reinforce the value of nirsevimab in pediatric immunization strategies.
- The study results can enhance public confidence in nirsevimab as an effective tool for RSV prevention.
Importance:
Nirsevimab, a long-acting monoclonal antibody, demonstrated efficacy against respiratory syncytial virus (RSV)-associated lower respiratory tract infections (LRTI) in clinical trials. Postlicensure monitoring is essential to confirm these benefits in clinical settings.
Objective:
To estimate the effectiveness of nirsevimab against medically attended RSV infections in infants and to assess how effectiveness varies by disease severity, dosage, and time since immunization.
Design, Setting, And Participants:
This test-negative case-control study utilized inpatient, outpatient, and emergency department data from the Yale New Haven Health System. Nirsevimab-eligible infants who were tested for RSV using polymerase chain reaction between October 1, 2023, and May 9, 2024, were included. Infants with RSV-positive results were cases and infants with RSV-negative results were controls.
Exposure:
Nirsevimab immunization, verified through state immunization registries.
Main Outcomes And Measures:
Effectiveness was estimated using multivariable logistic regression, adjusting for age, calendar month, and potential confounders. Separate models examined estimated effectiveness by clinical setting, dosage, time since immunization, and severity (defined as needing high-flow oxygen or intensive care unit admission). Broader outcomes were also analyzed, including all-cause LRTI and all-cause LRTI-associated hospitalization.
Results:
The analytic sample included 3090 infants (1722 male [57.3%]; median [IQR] age at testing, 6.7 [3.6-9.7] months), with 680 (22.0%) RSV-positive cases and 2410 (78.0%) RSV-negative controls. Nirsevimab uptake was 10.7% (330 patients), with 21 RSV-positive cases and 309 RSV-negative controls immunized. Adjusted effectiveness was 68.4% (95% CI, 50.3%-80.8%) against medically attended RSV infection, 61.6% (95% CI, 35.6%-78.6%) against outpatient visits, and 80.5% (95% CI, 52.0%-93.5%) against hospitalizations. The highest estimated effectiveness (84.6%; 95% CI, 58.7%-95.6%) was observed against severe RSV disease. Although estimated effectiveness against RSV infections declined from 79.3% (95% CI, 63.4%-90.6%) at 2 weeks postimmunization to 54.8% (95% CI, 16.3%-74.7%) at 14 weeks postimmunization, it remained significant. Estimated effectiveness did not vary substantially by dosage. During peak RSV season, nirsevimab appeared effective against all-cause LRTI (49.4%; 95% CI, 10.7%-72.9%) and all-cause LRTI-associated hospitalizations (79.1%; 95% CI, 27.6%-94.9%). From February to May 2024, when most LRTIs were caused by other viruses, its estimated effectiveness against these broader outcomes was negligible.
Conclusions And Relevance:
In this case-control study, nirsevimab provided substantial protection against RSV-associated outcomes. These findings support its continued use and provide evidence that may help boost public confidence in the immunization program.
