Clover Reports Positive Phase 2 Data for RSV + hMPV ± PIV3 Combination Vaccines in Older Adults
核心洞察
Clover's Phase 2 trial in 420 Australian adults aged 60–85 showed SCB-1022 (搜索) and SCB-1033 (搜索) produced 6-to-9-fold neutralizing antibody rises against RSV (搜索) and 6-to-8-fold against hMPV (搜索) at 28 days.
Adding PIV3 (搜索) antigen in SCB-1033 (搜索) caused no immune interference, and responses showed no drop-off in participants aged 75 and older compared to those aged 60–74.
Both candidates were generally well-tolerated with no vaccine-related serious adverse events, and Clover completed 2,000L commercial-scale production of all three antigen components.
Clover Biopharmaceuticals (搜索) announced positive preliminary data from a Phase 2 clinical trial in older adults in Australia evaluating SCB-1022 (搜索) (RSV (搜索) + hMPV (搜索)) and SCB-1033 (搜索) (RSV + hMPV + PIV3 (搜索)), two protein-based vaccine candidates built on prefusion-stabilized F (PreF (搜索))-Trimer subunit antigens using the company's Trimer-Tag vaccine technology platform. The randomized, observer-blinded, multi-center study enrolled 420 adults aged 60 to 85, who were randomized to receive SCB-1022, SCB-1033, or placebo.
"We are pleased to announce positive Phase 2 clinical data strengthening the potential first-in-class and best-in-class profile for our RSV (搜索)+hMPV (搜索)±PIV3 (搜索) combination vaccine candidates, with the potential differentiated ability to re-vaccinate individuals previously receiving approved RSV vaccines to restore and broaden protection," said Joshua Liang, Chief Executive Officer & Board Director of Clover.
Immunogenicity Results
Antibody titers (geometric mean titers [GMTs]) at 28 days post-vaccination in the Phase 2 trial were generally in-line with or trended higher than the prior Phase 1 trial. Geometric mean fold rises (GMFRs) in neutralizing antibodies (nAbs) at 28 days post-vaccination compared to pre-vaccination showed approximately 6-to-9-fold increases in RSV (搜索) nAbs and approximately 6-to-8-fold increases in hMPV (搜索) nAbs. PIV3 (搜索) nAbs demonstrated a greater than 3-fold increase, driven by up to approximately 20-fold increases in PIV3 PreF (搜索)-specific antibodies.
Notably, no drop-off in antibody responses was observed in the oldest participants (75 years and above) compared to younger participants (60–74 years). Additionally, no signs of immune interference on RSV (搜索) and hMPV (搜索) nAbs were observed from the addition of the PIV3 (搜索) PreF (搜索) antigen in SCB-1033 (搜索) compared to SCB-1022 (搜索).
Competitive Positioning and Re-Vaccination Potential
The finding that matters most for competitive positioning is the absence of immune interference. Adding the PIV3 (搜索) antigen in SCB-1033 (搜索) did not blunt RSV (搜索) or hMPV (搜索) responses compared to the two-pathogen formulation. Clover is explicitly positioning both candidates as options for people who already received Arexvy, Abrysvo, or mRESVIA to restore and broaden protection.
This framing shifts the clinical question from "does it work?" to "does it add coverage that single-pathogen RSV (搜索) vaccines cannot?" Phase 2 immunogenicity data cannot answer that definitively, but the pattern is consistent enough with Phase 1 to make the argument credible. CDC data from February 2026 puts RSV vaccination coverage at 43 percent among adults 75 and older, leaving a meaningful unvaccinated fraction.
Safety and Reactogenicity
SCB-1022 (搜索) and SCB-1033 (搜索) were generally well-tolerated. Solicited local and systemic adverse events (AEs) within 7 days of vaccination were mostly mild and all transient. The most common solicited AEs were fatigue, headache, and injection site pain, with mean durations of approximately 2 days for both the vaccine groups and the placebo group.
The frequency of unsolicited AEs within 28 days of vaccination was similar across the vaccine and placebo groups. There were no vaccine-related serious adverse events (SAEs), AEs of special interest (AESIs), or AEs leading to discontinuation.
Respiratory Tract Infection Signal
Approximately 62% lower rate of respiratory tract infection was observed in the vaccine groups (SCB-1022 (搜索) and SCB-1033 (搜索)) versus the placebo group within 28 days of vaccination, based on AE reporting of any respiratory tract infections. No PCR sequencing of infection cases was conducted in the study, so this number should be read as hypothesis-generating at best. A significant RSV (搜索) outbreak with co-circulation of hMPV (搜索) and PIV in Australia occurred during the study enrollment and follow-up period.
Commercial-Scale Manufacturing
In parallel with the Phase 2 trial, Clover conducted commercial-scale 2,000L bioreactor scale-up production of multiple batches of Trimer-Tagged RSV (搜索), hMPV (搜索), and PIV3 (搜索) PreF (搜索) antigen components of SCB-1022 (搜索)/1033. The successful 2,000L production process scale-up further de-risks future late-stage development and commercialization, which matters because manufacturing failures at scale have derailed protein-subunit programs before.
Next Steps
Based on these positive Phase 2 results, Clover will continue to evaluate mid- and late-stage development plans as well as potential global collaboration opportunities for value maximization. No Phase 3 start date has been announced. The commercial case for a three-pathogen combination ultimately rests on demonstrating that broader coverage translates to fewer hospitalizations, not just higher antibody titers—a question that requires an outcomes-powered Phase 3.