Nilsevimab shows 90% success in protecting infants from RSV hospitalization

In a recent study published in MMWR Morbidity and Mortality Weekly ReportA group of researchers evaluated the efficacy of nilsevimab in preventing RSV-related hospitalizations in infants during the first RSV season from October 1, 2023 to February 29, 2024.

report: Early estimates of the efficacy of nirsevimab for preventing respiratory syncytial virus-related hospitalizations in infants entering their first respiratory syncytial virus season — New Vaccine Surveillance Network, October 2023 to February 2024. Image credit: joshimerbin / Shutterstock

background

RSV causes significant hospitalizations among infants in the United States, with 50,000 to 80,000 cases occurring annually in children younger than 5 years. The risk is highest during the first few months of life, but the risk decreases as the child grows. In August 2023, the U.S. Centers for Disease Control and Prevention (CDC) approved nilsevimab for use in infants younger than 8 months and certain children 8 to 19 months of age for the first RSV season. In clinical trials, nirsevimab was shown to be 79% effective against her RSV-associated lower respiratory tract infections, rising to 81% on hospitalization. At the same time, a maternal RSV vaccine was also introduced. To address the shortage of nilsevimab, younger, higher-risk infants were initially prioritized, which was later expanded as supplies increased. Further studies are needed to assess the long-term efficacy and durability of nirsevimab protection against RSV, especially as immunity declines in diverse populations over time.

About research

The New Vaccine Surveillance Network (NVSN) is critically evaluating the effectiveness of vaccines against pediatric respiratory viruses in the United States by collecting comprehensive data from children under 18 years of age at seven pediatric centers. The study looked at infants younger than 8 months of age who were hospitalized with acute respiratory illness (ARI) between October 2023 and February 2024 and received nilsevimab vaccine. Targeted. Previous palivizumab administration, maternal RSV vaccination, or equivocal RSV test results were excluded. Analysis required a minimum of 5 infants per center who were vaccinated at least 1 week before onset of symptoms.

This study used a test-negative case-control design to evaluate the efficacy of nilsevimab in preventing RSV-related hospitalizations. Cases included infants with positive RSV tests, whereas controls were RSV negative. The effectiveness of vaccines given at least 7 days before symptoms appeared was considered. The analyzes used multivariate logistic regression and adjusted for factors such as age at enrollment, timing of illness, and high-risk status, but not for prematurity or insurance status.

research result

The comprehensive analysis conducted by NVSN initially included a total of 1,036 infants. Of these, 699 infants across four sites met the strict inclusion criteria established for this study. The cohort was divided into two groups: 407 infants (58%) were classified as case patients who tested positive for RSV, and the remaining 292 infants (42%) were control patients who tested negative for the virus. Ta.

A notable finding of this study was that infants with high-risk medical conditions had a higher incidence of nilsevimab treatment compared with infants without such conditions, with rates of 46% and 6%, respectively; A significant correlation is shown (p<0.001). This suggests a targeted approach when administering nilsevimab to infants considered to be at high risk for severe RSV disease. Interestingly, this analysis found no significant differences in nilsevimab dosing based on preterm infant status or insurance type, suggesting that it may be more effective in providing protection against RSV across different demographic and socio-economic groups. A unified approach has been pointed out.

This study further investigated participants' timeline from nilsevimab administration to the onset of ARI symptoms. Duration varied widely, ranging from 7 to 127 days, with a median duration of 45 days. This variability highlights the importance of timely vaccination and highlights the period of effective protection provided by nisevimab after administration.

In terms of effectiveness, the data revealed convincing statistics. Nilsevimab was 90% effective in preventing RSV-related hospitalizations in women, as evidenced by a comparison of vaccinated case patients and control patients. This high efficacy rate highlights the great potential of nirsevimab in protecting infants from serious RSV-induced health complications. Furthermore, the distribution of nilsevimab dosing varied between study sites, with rates ranging from 4% to 12%.

conclusion

In summary, in this study, nilsevimab demonstrated 90% efficacy in preventing RSV-related hospitalizations with a median interval from vaccination to onset of symptoms of 45 days. This initial estimate supports the recommended use of the vaccine to protect infants against severe RSV disease. The robustness of this study stems from a standardized approach to defining ARI, systematic RSV testing, and thorough validation of nilsevimab dosing with reliable records. However, the observed efficacy is expected to decrease over the course of the RSV season due to the natural decline in vaccine-induced antibody levels. This requires ongoing efficacy monitoring by CDC to continue to accurately understand the preventive efficacy of nilsevimab in real-world settings, particularly throughout the RSV season and in children 8 to 19 months of age, who are at increased risk. emphasizes the need.