Respiratory syncytial virus (RSV) plays a significant role in causing lower respiratory tract infections among older adults, leading to considerable illness and death. There is a significant potential of the adjuvanted RSVPreF3 vaccine in markedly lowering the burden of RSV disease among older adults aged 60 years and above in the US.

In this study, around 56.7 million adults aged 60 and older were vaccinated, reducing 2,954,465 symptomatic RSV-ARI cases over 3 years compared to scenarios without vaccination. This included a decrease of 321,019 cases of pneumonia confirmed by X-ray and 16,660 fewer deaths related to RSV. The vaccination effort also resulted in significant decreases in RSV-related healthcare utilization, including 203,891 hospitalizations, 164,060 visits to the emergency department, 1,577,586 outpatient visits, and 1,343,915 prescriptions for antibiotics over the same timeframe. A notable public health benefit was consistently observed through various sensitivity analyses.

“Our model’s base-case results are consistent with other decision analytic models that have estimated substantial public health benefits of RSV vaccination among older adults,” according to the investigators. “For example, Herring et al. found that vaccinating 65.3% of US adults aged ≥ 60 years with a hypothetical RSV vaccine with a VE of 50% against overall RSV and 65% against msLRTD would result in approximately 1.2 million fewer RSV infections overall, 323,000–396,000 fewer medically attended RSV cases, 44,000–82,000 fewer hospitalizations, and 8000–15,000 fewer deaths each year.”

This research evaluates the impact on public health of administering the adjuvanted RSVPreF3 vaccine to adults 60 years and older in the US. To project RSV-related outcomes over 3 years it used a static, multi-cohort Markov model for both vaccinated and unvaccinated scenarios. The primary analysis was based on influenza vaccine uptake rates, incorporating data from the literature and phase 3 trials of the adjuvanted RSVPreF3 vaccine. The outcomes of the model covered the clinical impact of RSV and the use of healthcare resources due to RSV.

“Vaccination can also make substantial contributions to reductions in antibiotic use, helping to potentially mitigate downstream antimicrobial resistance,” according to the investigators. “One recent study estimated that, globally, a total of 4.95 million antimicrobial resistance-associated deaths occurred in 2019. Over a 3-year period, vaccination with the adjuvanted RSVPreF3 vaccine is estimated to result in over 1.3 million fewer antibiotic prescriptions among older adults in the US, which can assist efforts in reducing antimicrobial resistance.”

This study has several assumptions and limitations, it relied on clinical trials, literature, and expert opinions for its input. It analyzed the impact of RSV vaccination in the general population of adults aged ≥60 years, not prioritizing those at higher risk of severe RSV. Although the adjuvanted RSVPreF3 vaccine is effective against RSV-LRTD, the analysis did not specifically account for vaccine efficacy (VE) against severe cases of RSV-LRTD, despite clinical trials showing high VE. It also did not consider disease attenuation from vaccination or broader healthcare system impacts beyond reduced visits and hospitalizations. Additionally, the model assumes RSV-related deaths only follow hospitalizations, potentially undercounting total RSV-related deaths by excluding other scenarios.

The adjuvanted RSVPreF3 vaccine is anticipated to offer significant public health benefits for older adults. This vaccine has the potential to prevent almost 3 million cases of symptomatic RSV-ARI among older adults in the US over 3 years, significantly reducing related morbidity and mortality. Achieving this level of public health benefit will require dedicated efforts to promote RSV vaccination, especially targeting older adults who are most at risk for severe RSV complications.

Reference

1. Molnar, D, La, E, Verelst, F, Poston S, Graham, et al. Public Health Impact of the Adjuvanted RSVPreF3 Vaccine for Respiratory Syncytial Virus Prevention Among Older Adults in the United States. Infectious Disease and Therapy. Published March 20, 2024. Accessed March 28, 2024. doi: https://doi.org/10.1007/s40121-024-00939-w