French CDMO Naobios and SGS are partnering to manufacture a respiratory syncytial virus (RSV) challenge agent for use in controlled human infection model (CHIM) studies conducted by SGS.
Produced under cGMP conditions, the human viral challenge agent (HVCA) is derived from a 2015 A-strain isolate that closely mirrors currently circulating RSV strains, with its realistic infection profile allowing researchers to generate robust, decision-enabling data on vaccine efficacy and immune response dynamics.
Naobios has already successfully completed the development, manufacturing and filling of several HVCAs for study use on the global market. HVCAs are used in strictly-controlled clinical trials (or CHIM studies) in which healthy volunteers are intentionally given a dose of a pathogen inoculated under rigorous ethical, regulatory and biosafety oversight to evaluate prophylactic vaccines or curative treatments.
These studies enable early and cost-efficient evaluation of RSV vaccines to prevent infection; in turn, this contributes to the accelerated development of effective and affordable vaccines against RSV.
To generate first‑in‑human proof-of-concept data, in October 2025 12 healthy participants were inoculated at the SGS Clinical Pharmacology Unit in Antwerp, Belgium, with the RSV A-strain challenge agent. The participants showed a 100% attack rate with mild, self-resolving pathology.
“In response to the growing use of CHIM studies, we have invested to extend our range of services, enabling us to meet the critical needs of clients worldwide,” said Eric Le Forestier, general manager of Naobios.
“This partnership with SGS demonstrates that Naobios continues to be a key global player and first-choice partner for viral challenge agent manufacturing in accordance with cGMP.”
Naobios has successfully manufactured and released 36 GMP batches of HVCA – including for SARS-CoV-2, RSV and hMPV, and influenza, leveraging this innovative approach to accelerate the vaccine development process, with clinical evaluation conducted by specialized CHIM centres such as SGS.
“Controlled human infection models are a powerful tool to de‑risk and accelerate early vaccine development when conducted under the highest scientific, ethical and biosafety standards,” said Jelle Klein, medical director, SGS CPU.
“Following GMP manufacturing of the RSV challenge agent by Naobios, SGS was responsible for the full clinical validation within a CHIM setting, including study design, clinical execution, safety oversight and virological assessments, enabling the generation of robust, decision‑enabling data for RSV vaccine and antiviral development. The clear step-by-step approach of Naobios provided us with a solid overview on which assessments were performed, when they were completed and what the results were. This provided us with full oversight of the process, allowing us to adjust clinical timelines based on emerging data.”