Adjuvanted RSVPreF3 can be co-administered with a COVID-19 mRNA vaccine in adults aged ≥50 years

Presented by

Dr Sofia Valenciano, GSK, Belgium

Conference

ESCMID Vaccines 2025

Adjuvanted RSVPreF3 co-administered with a COVID-19 mRNA vaccine was shown to be non-inferior to sequential administration 30 days apart, with acceptable safety and tolerability in adults aged ≥50, according to a report from the ESCMID Vaccines 2025 conference.

Dr Sofia Valenciano (GSK, Belgium) presented results of a phase 3 (NCT06374394), open-label, randomised (1:1) trial comparing co-administration of adjuvanted RSVPreF3 with a COVID-19 mRNA vaccine to administration of the two vaccines 30 days apart (control). Eligibility criteria included adults aged ≥50 years who had received at least 1 COVID-19 vaccine dose ≥3 months before study entry. The upper limit of the 2-sided 95% CI of geometric mean titre (GMT) ratios ≤1.50 was set as the non-inferiority success criterion for all three RSV-A, RSV-B and XBB 1.5 strains assessed. A total of 417 participants received co-administration, while 416 received control.

Co-administration of the two vaccines met the non-inferiority criteria for RSV-A (GMT ratio 1.12; 95% CI 0.97-1.28) and RSV-B (GMT ratio 1.08; 95% CI 0.94-1.23), but the upper limit of the 95%CI for the GMT ratio crossed 1.50 for XBB 1.5 (GMT ratio 1.31; 95%CI 1.13-1.51). In terms of safety, there was a trend for injection-site adverse events (AEs) to be higher in the co-administration group, mostly driven by injection-site pain (72.3% vs 64.2% at the COVID-19 vaccine site and 73.3% vs 58.5% at the adjuvanted RSVPreF3 site). No events of neurological demyelinating disorders or deaths were reported, while atrial fibrillation was reported in 1 participant in each group.

“The study results support co-administration of the adjuvanted RSVPreF3 vaccine with a COVID-19 mRNA vaccine”, concluded Dr Valenciano, adding that “the marginally missed non-inferiority criterion for the XBB.1.5 strain is not expected to be clinically meaningful. Adjuvanted RSVPreF3 co-administered with COVID-19 mRNA vaccine was well tolerated, with an acceptable reactogenicity and safety profile.”

Bonten M, et al. Co-administration of the AS01E-adjuvanted respiratory syncytial virus (RSV) prefusion F protein vaccine (adjuvanted RSVPreF3) with a COVID-19 mRNA vaccine in ≥50-year-old adults. 6^th ESCMID Vaccines, 10–13 September 2025, Lisbon, Portugal.

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