RSV Vaccines on the Horizon: Updates From IDWeek 2022

Key Takeaways

• “Tripledemic” (ie, COVID-19, influenza, and RSV) cases are increasing, resulting in increased hospitalizations in vulnerable patient populations.
• Several promising RSV vaccines that appear to be well-tolerated and demonstrate high efficacy rates in older adults are under investigation.

Respiratory syncytial virus ( recently has flooded the news with reports of increased transmission and hospitalizations across all age groups in the United States due to the “tripledemic” of COVID-19, influenza, and RSV. A similar pattern is emerging in Europe, and hospitals are starting to fill up for the winter season. Those most affected by RSV are children younger than 5 years of age, adults aged 65 years or older, and those with specific comorbidities.

According to the European Centre for Disease Prevention and Control, this year’s RSV season started 5 weeks earlier than normal, and positivity rates already are slightly higher than pre–COVID-19 seasons (2016/17, 2017/18, and 2019/20). There also has been a 5-fold increase in testing for RSV.

Although the RSV burden continues to affect children, older patients remain a vulnerable population at risk for severe disease and complications. During Week 47 of 2022, an RSV outbreak was reported in a nursing home in Ireland. In years past, outbreaks in nursing homes and long-term care facilities have been associated with significant case fatality rates.

Currently, no specific treatments for RSV are available for adults—but there has never been a more promising time in the field of RSV for older adults than now, with the exciting preventive therapies on the horizon.

In this commentary, I will share interim results for 3 RSV vaccines being studied in older adults from phase II and III clinical trials presented at IDWeek 2022.

RSVpreF
The RSVpreF vaccine targets , which is one of the proteins found on the viral surface. It is a bivalent vaccine candidate that targets both RSV A and RSV B strains. 

RENOIR is a randomized, placebo-controlled phase III clinical trial with more than 34,000 participants aged 60 years or older from 240 sites in 7 countries. Although immunocompromised individuals were excluded, approximately one half of study participants had high-risk conditions (eg, chronic cardiopulmonary conditions, diabetes, heart disease).

The RSVpreF vaccine was found to be 66.7% effective in preventing RSV-lower respiratory tract illness with 2 or more symptoms and 85.7% effective in preventing RSV- lower respiratory tract illness with 3 or more symptoms. No differences in local and systemic events resulted among groups.

Overall, RSVpreF appears to be well-tolerated, and initial data suggest high efficacy rates in older adults. Ongoing data are expected from the second RSV season.

RSVPreF3 OA Vaccine
The RSVPreF3 OA vaccine targets the preF protein and is inoculated with an adjuvant system to help boost an immune response.

Interim results from AReSVi-006, the ongoing randomized, observer-blind, placebo-controlled, multicenter phase III study, were presented at IDWeek 2022. Almost 25,000 patients aged 60 years or older were recruited.

The RSVPreF3 OA vaccine was found to be 82.6% effective in preventing RSV-lower respiratory tract disease (LRTD), with similar efficacy rates between the 2 RSV strains and among age groups. Injection-site pain, headache, fatigue, and myalgia were more commonly seen in those receiving RSVPreF3 OA compared with placebo.

Initial data on RSVPreF3 OA indicate high efficacy in older adults at preventing RSV-LRTD. The study continues to collect data to evaluate revaccination schedules and long-term protection over multiple RSV seasons.

Ad26.RSV.preF Vaccine
Ad26.RSV.preF combines the Ad26 vector and the recombinant RSV preF protein to induce both cellular and humoral responses.

Data over 3 RSV seasons in 5782 adults aged 65 years or older were shared from CYPRESS, a double-blind, placebo-controlled phase IIb study. An efficacy rate of 80% in preventing RSV-LRTD during the first RSV season resulted, and this efficacy rate was maintained through the third RSV season. Safety events were similar for all seasons evaluated.

In a subset of 195 participants, immunogenicity outcomes were evaluated up to Day 533. At 15 days post inoculation, the vaccine significantly increased the RSV-neutralizing antibody titer and preF immunoglobulin G (IgG) serum antibodies by 12.1-fold and 8.6-fold, respectively, compared with baseline. RSV preF IgG serum antibodies were well maintained over 1 year, and similarly RSV-neutralizing antibody titers remained 2.8-fold above baseline. RSV F-specific T-cell responses followed a similar pattern and were maintained over 1.5 years. Age or risk factors for severe RSV-LRTD were not found to affect these immunogenicity outcomes.

Based on the data, this vaccine candidate appears to be robust and durable, providing protection over several RSV seasons regardless of the patient’s age or risk level for RSV complications. Additional data are expected in the phase III study EVERGREEN.

Your Thoughts?
Which RSV vaccine candidate do you think is most promising? Join the discussion by posting a comment.