Pfizer’s RSV vaccine generates strong response in younger, immunocompromised adults
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Key takeaways:
- A dose of Abrysvo generated a strong response in immunocompromised adults younger than 59 years.
- Similar rates of adverse events were observed among the vaccine and placebo groups (7.1% vs. 7.6%, respectively).
Data from the MONeT study demonstrated that Pfizer’s respiratory syncytial virus vaccine was safe and elicited a strong response in younger adult patients at increased risk for disease.
“The MONeT study was initiated following the conclusion of the pivotal older adult and maternal studies that addressed the groups with the highest unmet need,” Iona Munjal, MD, executive director of vaccines research and development at Pfizer Inc., told Healio.
“Yet, adults of any age with certain underlying chronic conditions are at increased risk of developing, and being hospitalized for, RSV-associated lower respiratory tract disease,” Mujal said.
Currently, several groups have been recommended by the CDC’s Advisory Committee on Immunization Practices to receive RSV vaccinations. Currently, the committee recommends RSV vaccination for all adults aged 75 years or older and any adults aged 60 to 74 years with risk factors for severe RSV — a strengthening of its previous recommendation, which was based on shared clinical decision-making.
The committee has not, however, made recommendations for younger adults to receive Pfizer’s RSVpreF — branded as Abrysvo — which has already received FDA approval for adults aged 18 to 59 years at increased risk for disease.
Munjal explained that there is a need for RSV vaccination in younger populations — primarily patients aged between 18 and 59 years with underlying medical conditions. She cited CDC data, saying that 94.3% of adults aged 18 years or older who are hospitalized for RSV had at least one underlying medical condition and, among those hospitalized for RSV, 86% aged 18 to 49 years and 96% aged 50 to 59 years had at least one chronic medical condition.
To assess the safety and immunogenicity of Abrysvo in younger populations, Munjal and colleagues conducted a phase 3 randomized trial of patients aged 18 to 59 years at high risk for severe RSV disease who were randomly assigned 2:1 to receive one dose of Abrysvo or placebo.
According to the study, the primary safety endpoints included reactogenicity events and adverse events (AEs) through 7 days and at 1 month after vaccination and serious AEs (SAEs) and newly diagnosed chronic medical conditions throughout the study.
In total, 453 people received Abrysvo and 225 received placebo. Among the Abrysvo recipient group, median onset of reactogenicity events was 2 to 3 days and median duration was 1 to 2 days, whereas among the placebo group, onset and duration were 1 to 5 and 1 to 2 days, respectively.
Rates of AE through 1 month after vaccination were similar between the two groups (7.1% in the Abrysvo group vs. 7.6% in the placebo group), whereas no vaccine-related SAEs or newly diagnosed chronic medical conditions were reported in either group, according to the study.
The study also showed that 1 month after Abrysvo administration, neutralizing geometric mean titers for RSV-A and RSV-B “increased substantially” from before vaccination to 1 month after vaccination for high-risk adults aged 18 to 59 years, meeting noninferiority criteria. The researchers wrote that this observation was seen across many subgroups, including sex, race and prespecified medical conditions, and was similar for patients aged 18 to 49 and 50 to 59 years (17 to 17.9 for RSV-A and 18.4 to 18.7 for RSV-B).
Based on these findings, Munjal said she and colleagues are “excited to address a significant unmet need as Abrysvo is the first and only RSV vaccine for adults younger than 50 [years].”
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