Effectiveness of Nirsevimab Immunization in Spain: Preliminary Results and Implications

Content

● Introduction [ver].
● The first data on the effectiveness of nirsevimab in Spain are published [ver] | Aim [ver] | Methodology [ver] | Results [ver].
● Conclusions and limitations [ver].
● More information on this website, bibliographic references and recommended links [ver]. In a nutshell ● In the autumn and winter of 2023-24, all Spanish autonomous communities have offered immunization against RSV with nirsevimab. Acceptance of the measure has been excellent, with coverage ≥90%.
● The first estimates of the effectiveness of nirsevimab for the prevention of hospitalization due to lower respiratory tract infection (LRTI) associated with RSV have just been published.
● The study has been carried out in nine hospital centers in the Valencian Community, Murcia and Castilla y León.
● The target population for immunization with nirsevimab (born since April 1, 2023) in these regions has been 15,676 infants. Coverage with nirsevimab has been 88.9% to 98.6%.
● During the study period (October 1, 2023 to January 10, 2024), 166 hospitalizations due to LRTI were recorded, 95 of them with a positive RSV test. Among these, 53% were immunized, while in cases of BRIV not associated with RSV, 83% were immunized.
● Effectiveness with pooled data (test negative design): 70.2% (95% CI: 38.3% to 88.5%).
● Effectiveness with pooled data (sensitivity analysis using a screening design): 84.4% (95% CI: 76.8% to 90.0%).
● Conclusion: the effectiveness of immunization with nirsevimab was greater than 70% in preventing hospitalizations in infants under 9 months of age with LRTI associated with RSV. The data presented is preliminary and requires further investigation.

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Introduction

In July 2023, the Ministry of Health published its recommendations for the use of nirsevimab for the prophylaxis of infections caused by respiratory syncytial virus (RSV) in newborns and infants. Before, in March 2023, Galicia already announced that it would incorporate nirsevimab starting in the fall of the same year (Martinón-Torres F, Euro Surveill 2023). After that, other communities made similar announcements. Finally, in the month of October, all communities joined in and incorporated universal prophylaxis against RSV in their immunization programs for all infants born on or after April 1, 2023.

The coverage achieved, according to the data published by some communities, is high, showing the excellent acceptance of the intervention despite the novelty of the product used, nirsevimab, a synthetic monoclonal antibody.

Commented below are the first provisional data on the effectiveness of nirsevimab in Spain.

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The first data on the effectiveness of nirsevimab are published in Spain

The commented study is:

• López-Lacort M, et al. Early estimates of nirsevimab immunoprophylaxis effectiveness against hospital admission for respiratory syncytial virus lower respiratory tract infections in infants, Spain, October 2023 to January 2024. Euro Surveill. 2024;29(6):pii=2400046.

This article provides the first estimates of the effectiveness of nirsevimab against hospital admission for lower respiratory infections (LRTI). acute lower respiratory tract infections) associated with RSV (IRVB-RSV) in infants under 9 months of age, in three Spanish autonomous communities.

The study was funded, in part, by the Carlos III Health Institute with European funds from the Recovery, Transformation and Resilience Plan, and by the European Union -NextGenerationEU-.

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Aim

To provide preliminary estimates of the effectiveness of nirsevimab against hospitalization for LRTI caused by RSV in infants younger than 9 months.

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Methodology

• Study carried out between October 2023 and January 2024.
• Multicenter active hospital surveillance was carried out in nine hospitals located in three autonomous communities (five hospitals in the three provinces of the Valencian Community, three in the Region of Murcia and one in Castilla y León, Valladolid).
• In the reference regions, children born since April 1, 2023, eligible for immunization, were 15,676 (6.4% of the entire Spanish population with the same condition). In those who were admitted for respiratory infection, RSV detection tests were performed using a PCR test.
• Two designs were used: the screening method and the test-negative design, to evaluate the effectiveness of nirsevimab.

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Results

A total of 166 hospitalizations due to IRVB were included, and in 73 cases they were less than 3 months of age. In 95 patients it was LRTI-RSV and of these, 53% were immunized. Among the 71 cases of BRIV not associated with RSV, 83% were immunized.

The Tabla 1 (attached) shows immunization coverage with nirsevimab and hospitalizations of infants with LRTI in the three regions participating in the study. Immunization coverage per hospital is detailed (between 78.7% and 98.6%), as well as the number of hospitalizations due to BRI and BRI-RSV. In addition, the percentage of immunized and non-immunized infants in both groups and the rate of BRI-RSV per 1000 infants are reported.

The Tabla 3 (attached) shows the effectiveness of nirsevimab against hospitalization in infants due to LRTI-RSV according to the study centers and evaluation method.

Effectiveness with data grouped according to the evaluation method:

• With the screening method, it was found that the effectiveness was 86.9% in Murcia, 69.3% in Com. Valencian and 97.0% in Valladolid. The combined analysis of the data from the three regions showed an effectiveness of 84.4% (95% CI: 76.8% to 90.0%) in preventing hospitalizations due to BRI-RSV in infants.
• With the test-negative method, the grouped data of the Com. Valenciana and Murcia show an effectiveness of 70.2% (95% CI: 38.3% to 88.5%).

The results show that immunization with nirsevimab was at least 70% effective in preventing hospitalizations in infants younger than 9 months with RSV-positive lower respiratory tract infections. However, it did not show protection against hospitalizations for non-RSV lower respiratory tract infections.

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Conclusions and limitations

• The authors suggest that nirsevimab could have a significant impact on the health burden associated with RSV, although more studies are needed to confirm these preliminary results.
• The effectiveness of nirsevimab is relevant to guide decision-making in Public Health, due to the impact of RSV disease in infants on the healthcare pressure on health systems during winter periods.
• The authors refer to some limitations, such as variability in effectiveness estimates due to differences in RSV circulation, hospitalization policies, and case definitions.

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More information on this website

Bibliographic references and recommended links

• López-Lacort M, et al. Early estimates of nirsevimab immunoprophylaxis effectiveness against hospital admission for respiratory syncytial virus lower respiratory tract infections in infants, Spain, October 2023 to January 2024. Euro Surveill. 2024;29(6):pii=2400046. ►Commented on: CIDRAP, February 9, 2024.
• Martinón-Torres F, et al. Early lessons from the implementation of universal respiratory syncytial virus prophylaxis in infants with long-acting monoclonal antibodies, Galicia, Spain, September and October 2023. Euro Surveill. 2023;28(49):pii=2300606.

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2024-02-12 06:34:50
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