• RSV-associated hospitalization rates among infants aged 0-7 months decreased significantly (28%-43%) in the US during the 2024-2025 season, coinciding with the introduction of maternal RSV vaccine and nirsevimab.
• The most significant rate reduction was observed in infants aged 0-2 months (45%-52%), who are at the highest risk for RSV-related hospitalizations.
• Increased hospitalization rates among older children (8-59 months), ineligible for the new prevention products, suggest a more severe RSV season overall, potentially underestimating the impact of the interventions on infants.

The introduction of maternal RSV vaccine and nirsevimab in the US during the 2024-2025 RSV season aimed to prevent severe RSV disease among infants and young children. An interim evaluation by the CDC compared RSV-associated hospitalization rates among children aged <5 years for the 2024–25 and 2018–20 RSV seasons using data from RSV-NET and NVSN surveillance networks. The results indicated significantly lower hospitalization rates among infants aged 0–7 months, particularly those aged 0–2 months, suggesting that widespread availability of these prevention products had a substantial positive impact on infant health.

• What: A significant decrease in RSV-associated hospitalizations among infants aged 0-7 months in the US during the 2024-2025 RSV season, linked to the introduction of maternal RSV vaccine and nirsevimab.
• Who: Infants aged 0-7 months, pregnant women (receiving RSV vaccine), healthcare providers administering vaccines and monoclonal antibodies, CDC, RSV-NET, NVSN.
• When: October 2024 – February 2025 (study period); RSV seasons 2018-2020 (comparison period).
• Where: United States (data from multiple states via RSV-NET and NVSN surveillance networks).

The CDC report provides compelling evidence of the positive impact of RSV prevention products on infant health in the US. The observed reduction in hospitalization rates, particularly among the most vulnerable age group (0-2 months), is a significant achievement. However, the increase in hospitalization rates among older children, who were ineligible for the interventions, suggests that the overall RSV season was severe. This highlights the importance of continued surveillance and efforts to optimize the implementation of RSV prevention strategies. The CIDRAP article further supports the effectiveness of nirsevimab, reporting significant reductions in respiratory infections in Spain. While the STAT news highlights the challenges with rollout, the AP article points to broader implications for infant mortality, painting a picture of significant progress due to these new preventative measures.

Although we need to do more, we know now that we can dramatically lower hospitalization rates due to severe RSV disease in young infants using our new tools — monoclonal antibodies and maternal immunization.

The findings from this study indicates that we are on the right path in reducing the risk of RSV hospitalizations in infants.

These data highlight the huge impact of this preventive strategy in reducing the number of severe LTRI in infants, which, before nirsevimab, was one of the most significant challenges faced by healthcare systems worldwide.

The introduction of maternal RSV vaccines and nirsevimab has significantly decreased RSV-associated hospitalizations among infants in the US, marking considerable progress in safeguarding infant health. However, challenges persist, including ensuring equitable access across various demographics, addressing vaccine hesitancy, and tackling financial barriers. Disparities in vaccine uptake related to race/ethnicity, socioeconomic status, and geographic location require targeted interventions to improve coverage. Continuous monitoring for potential escape variants and long-term impacts, such as those on asthma development, is essential. Furthermore, research is needed to optimize RSV prevention strategies, explore novel vaccine candidates, and develop cost-effective solutions suitable for low- and middle-income countries, where the burden of RSV is disproportionately high. Addressing these challenges through broad, age-based recommendations, increased public awareness, and improved access to preventative care will be crucial for maximizing the global impact of RSV prevention efforts and reducing the burden of this common respiratory virus.