RSV Vaccine Updates From IDWeek 2022

Key Takeaways

• An effective RSV vaccine is estimated to substantially reduce RSV-related complications (eg, lower respiratory tract disease, hospitalizations, death).
• Several RSV vaccine candidates are being investigated in older adults, with many phase III studies underway.

A vaccine against respiratory syncytial virus (RSV) has great potential to make a huge clinical impact for older adults in the United States. Based on a decision-analytic model by Fust and colleagues, an effective RSV vaccine (ie, 75% efficacy) is estimated to substantially reduce RSV acute respiratory disease and RSV lower respiratory tract disease (RSV-LRTD) and, as a result, decrease RSV-related hospitalizations and deaths in adults aged 60 years or older. From their estimate, approximately 2.4 million cases of RSV acute respiratory disease could be prevented with an RSV vaccine.

At the time of this writing, no RSV vaccines are approved by the FDA, but several candidates are being investigated in older adults. Here are the latest updates on RSV vaccines from the IDWeek 2022 meeting.

RSVPreF Vaccine
RSVPreF is a bivalent vaccine using the stabilized prefusion F protein (preF) and is based on both RSV A and B strains.

RENOIR is an ongoing randomized, double-blind, placebo-controlled phase III study evaluating the safety and efficacy of the RSVPreF vaccine vs placebo in adults 60 years of age or older.

Interim results of more than 6000 patients were shared this year. The RSVPreF vaccine was found to be safe and well tolerated; local and systemic events were mostly mild to moderate and short lived. The vaccine demonstrated a 66.7% efficacy rate against RSV-LRTD with ≥2 respiratory symptoms and 85.7% efficacy against RSV-LRTD with ≥3 symptoms.

Priority Review designation from the FDA was accepted on December 7, 2022, for RSV prevention in older adults, expediting the drug review and approval process. A decision by the FDA is expected in May 2023.

RSVPreF3 OA Vaccine
The RSVPreF3 OA vaccine uses the RSVPreF3 antigen and is combined with an ASO1E adjuvant system to help boost immune responses in older adults.

AReSVi-006 is an ongoing phase III trial of adults 60 years of age or older randomized to receive the vaccine or placebo. Preliminary efficacy results were reported at 12 months for approximately 25,000 study participants. Vaccine efficacy rates against RSV acute respiratory infection, RSV-LRTD, and severe RSV-LRTD were 71.7%, 82.6%, and 94.1%, respectively. No safety concerns were identified. In further analyses, efficacy rates were similar despite RSV strain and were consistently high in participants aged 60-69 and 70-79 years, as well as prefrail older adults and those with comorbidities.

On November 2, 2022, the FDA accepted a Biologics License Application and granted Priority Review for this vaccine.

The use of the RSVPreF3 OA vaccine also is being evaluated in combination with the seasonal quadrivalent influenza vaccine in adults 60 years of age or older in the RSV-007 study. Coadministration of both vaccines resulted in noninferiority of immunogenicity compared with sequential administration. In addition, no differences in safety were observed, supporting the use of simultaneous vaccination of RSVPreF3 OA and the quadrivalent influenza vaccine.

Ad26.RSV.preF–Based Vaccine
The Ad26.RSV-preF‒based vaccine uses a modified adenovirus (serotype 26) vector encoding RSV F protein that is stabilized in its preF confirmation. Breakthrough Therapy Designation was received for the Ad26.RSV-preF‒based vaccine in 2019.

Data are available from CYPRESS, a randomized, double-blind, placebo-controlled phase IIb study. A single vaccination of the Ad26.RSV.preF plus RSVpreF protein vaccine was examined in approximately 6000 adults aged 65 years or older and compared with placebo. Vaccine efficacy was evaluated over 3 RSV seasons.

After the first RSV season, the vaccination was found to be 80% efficacious against RSV-LRTD. Efficacy was maintained through RSV seasons 2 and 3 with an efficacy rate of 78.7% across the 3 seasons; however, RSV B was the only strain identified in the last 2 seasons. Vaccine durability was not affected by age or risk factors for severe RSV-LRTD. The vaccine’s safety profile was consistent with prior studies.

A phase III clinical trial further assessing the Ad26.RSV.preF‒based vaccine is underway in EVERGREEN. Efficacy, safety, and immunogenicity of the vaccine will be assessed in up to 27,000 adults aged 60 years or older across the globe.

mRNA-1345 Vaccine
mRNA-1345 is another potential vaccine candidate that was granted Fast Track Designation by the FDA in 2021 for adults aged 60 years or older. The mRNA-1345 vaccine encodes the preF glycoprotein through a modified mRNA delivery. Once inside the cells, the RNA produces preF to prevent RSV infection. This vaccine contains the same lipid nanoparticle as the mRNA COVID-19 vaccine.

Chen and colleagues shared safety and immunogenicity of mRNA-1345 from the phase I study. The vaccine was well-tolerated. In all dose levels tested, neutralizing and binding antibody levels were boosted in younger adults (aged 18-49 years) and older adults (aged 65-79 years). Further safety and efficacy data in older adults are expected in ConquerRSV, a randomized, observer-blind, placebo-controlled phase II/III study.

Your Thoughts?
If approved, would you recommend an RSV vaccine for your older adult patients? Join the discussion by posting a comment.