hVIVO (HVO ) has highlighted its long-running work with Cidara Therapeutics after Merck Sharp & Dohme (MSD) agreed to acquire the US biotech in a transaction valued at about $9.2 billion, following positive data from Cidara’s influenza candidate CD388. The deal underlines the role of hVIVO’s human challenge and field study platform in accelerating high-profile infectious disease programmes.

Cidara’s lead asset CD388 is an investigational, long-acting, strain-agnostic antiviral designed to prevent influenza infection in higher-risk individuals, offering protection against both influenza A and B. It is currently in Phase III clinical development and has been granted Breakthrough Therapy Designation and Fast Track Designation by the US Food and Drug Administration.

hVIVO has worked with Cidara throughout CD388’s development, first generating early proof-of-concept data through a randomised, double-blind influenza human challenge trial in healthy volunteers completed in 2023. The study enrolled 59 participants and showed that CD388 reduced total viral load (area under the curve) versus placebo, with lower peak viral loads measured by both qPCR and cell culture in treated participants.

Building on that work, hVIVO then acted as the sole UK site in Cidara’s Phase IIb field study during the 2024 / 2025 flu season, assessing CD388’s protective efficacy in healthy adults. The company screened more than 1,100 participants and dosed 817 within six weeks, delivering its largest-ever field trial cohort and achieving the highest recruitment numbers of any participating site worldwide. The Phase IIb read-out showed that all primary and secondary endpoints were met, and hVIVO is now a major clinical site in the ongoing multi-site Phase III trial.

In addition, hVIVO has served as the central virology laboratory across both the CD388 Phase IIb and Phase III programmes. Its remit spans scientific consultancy, preparation of sample collection kits, management of global virology sample logistics, and delivery of multiple virology and immunology assays, including the primary endpoint analysis.

hVIVO’s Chief Executive Dr Yamin 'Mo' Khan said: "We congratulate Cidara on this landmark transaction in the infectious disease space with MSD. For hVIVO, this demonstrates that our human challenge trial expertise can indeed lead to significant downstream value creation. It also validates hVIVO's diversification into field studies and standalone laboratory services, facilitated by our highly efficient patient recruitment and site services along with our extensive infectious disease knowledge and capabilities. We are proud to have supported CD388 from early proof-of-concept through Phase IIb and into Phase III, and we look forward to patients benefitting from this innovative therapy."

View from Vox

MSD’s move to buy Cidara gives external validation to hVIVO’s strategy of combining human challenge trials with large-scale field studies and central lab services. The CD388 story showcases how early challenge data can feed into late-stage development and, ultimately, high-value strategic deals, reinforcing hVIVO’s positioning in influenza and broader infectious disease drug development.