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EuRSV Completes Phase 1 Study, Demonstrating Favorable Safety and Immunogenicity
JULY 28, 2026
EuPOP Life Sciences’ respiratory syncytial virus (RSV) vaccine program has completed a Phase 1 clinical study in South Korea, with results demonstrating a favorable safety profile and encouraging immune responses across the evaluated vaccine groups.
The study, conducted by EuBiologics, enrolled 100 healthy adults between 19 and 80 years of age. It was designed as a randomized, observer-blinded, placebo-controlled trial evaluating two vaccine candidates, RSV-1 containing QS-21 and RSV-2 without QS-21, at both low and high dose levels.
Participants received two vaccinations four weeks apart and were followed for up to 52 weeks to assess safety and immunogenicity.
Across the study, the vaccine candidates were generally well tolerated. No vaccine-related serious adverse drug reactions, adverse events of special interest, or immediate adverse events were reported. Most observed reactions, including injection-site pain and tenderness, fatigue, headache, and muscle pain, were mild to moderate and resolved without significant complications. The 52-week follow-up also identified no new safety concerns.
The Phase 1 study also generated encouraging immunogenicity findings. Compared with placebo, all vaccine groups showed meaningful increases in RSV-specific IgG antibodies as well as neutralizing antibodies against both RSV-A and RSV-B. Cellular immune responses, including IFN-γ and TNF-α responses, were also effectively induced.
Among the evaluated formulations, the high-dose RSV-2 group generated the strongest neutralizing antibody response, while RSV-1 demonstrated a more pronounced cellular immune response. These findings provide important data for selecting the optimal formulation and dose for further clinical development.
Based on the Phase 1 results, the program is expected to advance toward Phase 2 development following selection of the preferred vaccine candidate and dose regimen. The next stage will involve evaluation in a larger study population to further characterize safety and immune responses.
Completion of the Phase 1 study represents an important clinical milestone for EuPOP’s RSV vaccine program and supports the continued development of next-generation vaccine candidates based on advanced liposomal vaccine technologies. EuPOP intends to build on these findings as it advances the program toward broader global clinical development and potential entry into the international RSV vaccine market.
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