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Updated: Feb 27, 2026
An Improved and High Throughput Respiratory Syncytial Virus RSV Micro-neutralization Assay
Published on: January 26, 2019
Bivalent RSVpreF Subunit Vaccine Safety and Immunogenicity in Seropositive 2-<18 Year Olds
Julia Glanternik1, Grant C Paulsen2, Shelly Senders3
1Pfizer Vaccines, Pfizer Inc., Pearl River, NY 10965, USA.
Insights
The RSVpreF vaccine demonstrated safety and immunogenicity in children aged 2 to 18 years. This study supports further clinical development of the respiratory syncytial virus (RSV) vaccine in pediatric populations.
Area of Science:
- Pediatric Vaccinology
- Immunology
- Infectious Diseases
Background:
- Respiratory Syncytial Virus (RSV) poses a significant health risk to children.
- Developing effective vaccines for pediatric populations is crucial for public health.
- Previous RSV vaccine development has faced challenges in achieving both safety and efficacy.
Purpose of the Study:
- To evaluate the safety and immunogenicity of different dose levels of the RSVpreF vaccine.
- To determine optimal vaccine dose levels for further clinical trials in children aged 2 to <18 years.
- To assess reactogenicity and adverse events following vaccination in pediatric participants.
Main Methods:
- Phase 1, open-label, age-descending Picasso trial.
- Inclusion of RSV-seropositive children aged 2-<5 and 5-<18 years, healthy or with chronic conditions.
- Administration of single RSVpreF doses (60 µg or 120 µg) with safety and antibody response assessments.
Main Results:
- 127 participants received RSVpreF; most events were mild/moderate.
- No vaccine-related serious adverse events or withdrawals reported.
- Significant increases in RSV-A and RSV-B neutralizing antibody titers observed one month post-vaccination.
Conclusions:
- RSVpreF vaccine is safe and well-tolerated in children aged 2-<18 years.
- The vaccine elicits robust immune responses, supporting its further development.
- Positive safety and immunogenicity data support continued clinical evaluation in pediatric populations, including those with chronic conditions.
Abstract:
Background/Objectives: We aimed to determine safe and immunogenic RSVpreF vaccine dose levels for further clinical development in 2-<18 year olds. Methods: The phase 1, age-descending, open-label Picasso trial evaluated different RSVpreF dose levels in respiratory syncytial virus (RSV)-seropositive 2-<5 year olds and 5-<18 year olds who were either healthy or had chronic medical conditions with increased RSV illness risk. Participants received a single dose of RSVpreF (60 µg or 120 µg dose level). The primary objective was to describe safety and tolerability at each dose level and age group, including frequencies of reactogenicity and adverse events (AEs). The secondary objective was to describe RSV neutralizing antibody responses at each dose level and age group 1 month after vaccination. Results: Overall, 127 participants received RSVpreF 60 µg (2-<5 year olds, n = 20; 5-<18 year olds, n = 35) or 120 µg (n = 24 and n = 48, respectively); 54% were male and 69% were White. Local reactions and systemic events were reported in 17-20% and 33-45% of 2-<5 year olds, respectively, and 49-56% and 52-60% of 5-<18 year olds; most were mild or moderate in severity. AEs were reported in 13-15% of 2-<5 year olds and 8-14% of 5-<18 year olds. No AEs leading to withdrawal or vaccine-related serious AEs were reported. RSV-A and RSV-B neutralizing titer geometric mean fold rises from before to 1 month after vaccination with RSVpreF 60 and 120 µg, which were 17.7-20.6 and 42.8-39.8, respectively, in 2-<5 year olds, and 19.0-23.5 and 20.3-20.3, respectively, in 5-<18 year olds. Conclusions: RSVpreF was safe, well tolerated, and elicited immune responses in RSV-seropositive 2-<18-year-old participants, supporting further clinical development in this pediatric population, including those with chronic conditions.
